Action plan to help patients with lung disease cope with wildfire smoke

A multidisciplinary team of UC Davis Health experts are calling on health systems to create wildfire preparedness action plans to support patients with preexisting respiratory diseases. They are urging providers to proactively put in place interventions to mitigate the effects of poor air quality from smoke.

Their article, published in the Journal of the COPD Foundation, identifies the needs of high-risk populations when affected by wildfire smoke. It outlines an action plan for health systems to help these groups with the burdens of poor air quality from wildfires.

"Patients being treated for respiratory conditions are at high-risk of exacerbations of symptoms when they are exposed to wildfire smoke," said Reshma Gupta, chief of population health and accountable care at UC Davis Health and co-author of the article. "Unfortunately, wildfire frequency and severity are increasing in the United States and negatively affecting these clinically at-risk and underserved communities. So, there is a significant need for us to install interventions to mitigate the health threat posed by wildfires."

Health impacts of poor air quality

Many components of wildfire smoke can have adverse impacts on health, especially for those with preexisting respiratory diseases.

Currently more than 34 million people living in the United States live with a chronic lung disease like asthma, chronic obstructive pulmonary disease (COPD) or Alpha-1 antitrypsin deficiency (AATD) according to the American Lung Association.

Exposure to wildfire-related air pollutants has been shown to cause and exacerbate diseases of the lungs, heart, brain and nervous system, skin and other major organs.

For patients being treated for preexisting respiratory conditions, poor air quality causes inflammation in the lungs. This can exacerbate symptoms and lead to emergency department visits and hospitalizations.

"Poor air quality can trigger exacerbations -- acute increase in shortness of breath, cough, dyspnea -- even leading to hospitalization," explained Brooks Kuhn, co-director of the Comprehensive COPD Clinic at UC Davis Health and co-author of the article. "The impact is not just transient: Respiratory exacerbations lead to persistent and accelerated worsening of lung function."

And adults are not the only ones at risk for these complications.

"Children also see these impacts when they are exposed to poor air quality from wildfires," said Kiran Nandalike, chief of pediatric pulmonology at UC Davis Children's Hospital. "As we see more wildfires impacting our communities each year, the urgency for health systems to outline a response to support patients is pressing."

Wildfire population health approach

The targeted wildfire preparedness action plan adopted by UC Davis Health uses a population health approach. This means care teams with providers from different specialties proactively work with patients who are at higher risk of developing symptoms from poor air quality.

"A population health approach zeroes in on targeted interventions tailored to specific communities or population groups," Gupta explained. "This approach considers a range of determinants, including social, economic, environmental and behavioral factors, which affect the health of these groups."

The team's wildfire preparedness action plan includes:

• Identifying clinically at-risk and underserved patient populations using well-validated, condition-targeted registries
• Assembling multidisciplinary care teams to understand the needs of these communities and patients
• Creating custom analytics and wildfire-risk stratification
• Developing care pathways based on wildfire-risk tiers by disease, risk of exposure and health care access
• Identifying outcome measures tailored to interventions with a commitment to continuous, iterative improvement efforts

"We have seen population health approaches be successfully implemented to support patients with dementia, chronic kidney disease, and cancer," Gupta said. "Using this model, we can adapt to the threat of poor air quality from wildfires and adopt a proactive approach to meet the needs of clinically at-risk and underserved patients."

UC Davis Health experience with wildfires

As the regional academic health system in Northern California, UC Davis Health has been at the epicenter of recent wildfires -- including the recent Park Fire, the fourth largest in California history. Because of this experience, the health system team has experience caring for patients in the most affected areas.

Read more at Science Daily

Targeted household cleaning can reduce toxic chemicals post-wildfire

After the last embers of a campfire dim, the musky smell of smoke remains. Whiffs of that distinct smokey smell may serve as a pleasant reminder of the evening prior, but in the wake of a wildfire, that smell comes with ongoing health risks.

Wildfire smoke is certainly more pervasive than a small campfire, and the remnants can linger for days, weeks and months inside homes and businesses.

New research from Portland State's Elliott Gall, associate professor in Mechanical and Materials Engineering, examined how long harmful chemicals found in wildfire smoke can persist and the most effective ways to remove them with everyday household cleaners.

Wildfires create compounds called polycyclic aromatic hydrocarbons (PAHs), which are formed in the combustion process at high temperatures.

These compounds are highly toxic.

"They are associated with a wide variety of long-term adverse health consequences like cancer, potential complications in pregnancy and lung disease," Gall said.

"So if these compounds are depositing or sticking onto surfaces, there are different routes of exposure people should be aware of. By now, most people in Portland are probably thinking about how to clean their air during a wildfire smoke event, but they might not be thinking about other routes of exposure after the air clears."

Public messaging is fairly consistent on what to do during a fire to reduce exposure to smoke -- close windows and doors, run an air purifier and consider wearing a mask -- but messaging is limited about what to do post-wildfire.

Gall's study published in Environmental Science & Technology looked at the accumulation and retention of PAHs over a period of four months on three different indoor materials: glass, cotton and air filters.

"We looked at a limited number of materials and we intentionally included some that are common in indoor environments," Gall said.

Initial findings showed that levels of PAHs remained elevated for weeks after exposure.

After materials were loaded with PAHs from wildfire smoke, it took 37 days for PAHs to decrease by 74% for air filters, 81% for cotton and 88% for glass.

That reduction is significant but it takes time and means increased health risks from elongated exposure.

However, laundering cotton materials just one time after exposure to smoke reduced PAHs on the material by 80%. Using a commercial glass cleaner on glass materials like windows and cups reduced PAHs between 60% and 70%.

Unlike glass and cotton, air filters can't be cleaned and need to be replaced after an extreme smoke event.

"Even if there's potentially some more life in them, over time PAHs can partition off the filter and be emitted back into your space," Gall said.

"While it may be a slow process, our study shows partitioning of PAHs from filters and other materials loaded with smoke may result in concentrations of concern in air. And while that partitioning is occurring, dermal contact and ingestion of PAHs from the materials may be important. One example might be holding and drinking from a glass that was exposed to wildfire smoke."

Gall said it was important to consider the effect of cleaning solutions available to the average person.

Although the findings also open the door to additional questions.

Read more at Science Daily

Research shows wildfire smoke may linger in homes long after initial blaze

Newly published research on indoor air quality from Colorado State University shows wildfire smoke may linger in homes long after the initial blaze has been put out or winds have shifted.

The findings, published in Science Advances, show that wildfire smoke can attach to home surfaces like carpet, drapes or counters -- extending the exposure for those inside and potentially causing health problems even after an initial cleaning activity by air purifiers. However, Professor Delphine Farmer said the research also shows that simple surface cleaning -- like vacuuming, dusting or mopping -- can reduce exposure and limit risk.

The research illustrates the hidden and persistent health threats many in the Western U.S. are facing given the increase in wildfires over the last decade, she said.

"This research shows that events like the Marshall Fire in Colorado, the wildfires in Canada and the recent fires in Hawaii present serious exposure potential -- not just when they occur but well after," said Farmer, who is based in the Department of Chemistry at CSU. "This paper is a key initial step towards providing actionable and practical information on how to protect yourself and clean your home."

To better understand how smoke enters and then stays in buildings, researchers burned pine wood chips in a net zero energy residential testing facility operated by the National Institute of Standards and Technology (NIST) in Maryland. That facility is frequently used to study how different systems impact the ways energy, water and air move through a single-family house. The detailed instrumentation available for that work was perfectly suited to this research, said Dustin Poppendieck, an environmental researcher at NIST who helped coordinate the project.

"The NIST Net Zero House allowed the researchers to track the movement and transformation of chemicals in the air and onto surfaces in real time using instruments in ways that don't interfere with the behavior of the smoke," said Poppendieck.

Those smoke injection sessions occurred regularly over several days, and Farmer said the total amount applied was comparable or slightly under the particulate levels seen during the Canadian wildfires. The team then took careful measurements of air quality levels and surface conditions after opening exterior doors and windows, cleaning and use of the home's built-in air cleaning systems.

The CSU team was particularly interested in the gas-phase of compounds developing from the smoke, while other teams from the University of California San Diego, CU Boulder and the University of North Carolina Chapple Hill explored different phases and interactions across the home. The team then compared findings between states to confirm what was actually happening in the home after the burn.

Farmer said findings from this interdisciplinary research approach could also be applicable to other large air pollution events like the train derailment in East Palestine, Ohio, where the same principles of compounds sticking to surfaces are likely to occur.

Because there has not been a lot of similar indoor air research, the team leaned on previous findings from others around the effects of cigarette smoke to inform their approach. Farmer said burning nicotine causes specific compounds with well-known health concerns and that the comparison to their project findings was informative.

"Nicotine reacts on surfaces to create a particularly nasty set of compounds called nitrosamines, which is where the real concern from thirdhand smoke that is left behind comes from," she said. "Whereas with wildfire smoke, we found there was a huge diversity of organic compounds that stick to surfaces, which then slowly bleed off."

The amount, persistence and variety of compounds from the wildfire smoke in each case could potentially change the recommended approaches for cleaning the indoor spaces. Farmer said that is an area of research the team hopes to explore in the future. For now, she said the team was able to show that the amount of smoke left on surfaces was proportional to the surface area that was cleaned. That means simple cleaning and specifically addressing large but little noticed spaces that may trap harmful compounds such as cabinets and HVAC systems could be beneficial right away.

"As we continue this research, we would like to know just how effective different cleaning approaches are and when residents should move from relatively simple steps like using commercial cleaning supplies for mopping to more drastic steps like replacing the drywall altogether," Farmer said.

Farmer's team was also recently funded by the W.M. Keck Foundation to research how smog may enter and remain in the home in much the same way as wildfire smoke. That work will be particularly important in Colorado where ground-level ozone pollution is a continuing issue.

Read more at Science Daily

Smoke particles from wildfires can erode the ozone layer

A wildfire can pump smoke up into the stratosphere, where the particles drift for over a year. A new MIT study has found that while suspended there these particles can trigger chemical reactions that erode the protective ozone layer shielding the Earth from the sun's damaging ultraviolet radiation.

The study, which will appear in Nature, focuses on the smoke from the "Black Summer" megafire in eastern Australia, which burned from December 2019 into January 2020. The fires -- the country's most devastating on record -- scorched tens of millions of acres and pumped more than 1 million tons of smoke into the atmosphere.

The MIT team identified a new chemical reaction by which smoke particles from the Australian wildfires made ozone depletion worse. By triggering this reaction, the fires likely contributed to a 3-5 percent depletion of total ozone at mid-latitudes in the southern hemisphere, in regions overlying Australia, New Zealand, and parts of Africa and South America.

The researchers' model also indicates the fires had an effect in the polar regions, eating away at the edges of the ozone hole over Antarctica. By late 2020, smoke particles from the Australian wildfires widened the Antarctic ozone hole by 2.5 million square kilometers -- 10 percent of its area compared to the previous year.

It's unclear what long-term effect wildfires will have on ozone recovery. The United Nations recently reported that the ozone hole, and ozone depletion around the world, is on a recovery track, thanks to a sustained international effort to phase out ozone-depleting chemicals. But the MIT study suggests that as long as these chemicals persist in the atmosphere, large fires could spark a reaction that temporarily depletes ozone.

"The Australian fires of 2020 were really a wake-up call for the science community," says Susan Solomon, the Lee and Geraldine Martin Professor of Environmental Studies at MIT and a leading climate scientist who first identified the chemicals responsible for the Antarctic ozone hole. "The effect of wildfires was not previously accounted for in [projections of] ozone recovery. And I think that effect may depend on whether fires become more frequent and intense as the planet warms."

The study is led by Solomon and MIT graduate student Peidong Wang, along with collaborators from the Institute for Environmental and Climate Research in Guangzhou, China, the National Oceanic and Atmospheric Administration, the National Center for Atmospheric Research, and Colorado State University.

Chlorine cascade

The new study expands on a 2022 discovery by Solomon and her colleagues, in which they first identified a chemical link between wildfires and ozone depletion. The researchers found that chlorine-containing compounds, originally emitted by factories in the form of chlorofluorocarbons (CFCs), could react with the surface of fire aerosols. This interaction, they found, set off a chemical cascade that produced chlorine monoxide -- the ultimate ozone-depleting molecule. Their results showed that the Australian wildfires likely depleted ozone through this newly identified chemical reaction.

"But that didn't explain all the changes that were observed in the stratosphere," Solomon says. "There was a whole bunch of chlorine-related chemistry that was totally out of whack."

In the new study, the team took a closer look at the composition of molecules in the stratosphere following the Australian wildfires. They combed through three independent sets of satellite data and observed that in the months following the fires, concentrations of hydrochloric acid dropped significantly at mid-latitudes, while chlorine monoxide spiked.

Hydrochloric acid (HCl) is present in the stratosphere as CFCs break down naturally over time. As long as chlorine is bound in the form of HCl, it doesn't have a chance to destroy ozone. But if HCl breaks apart, chlorine can react with oxygen to form ozone-depleting chlorine monoxide.

In the polar regions, HCl can break apart when it interacts with the surface of cloud particles at frigid temperatures of about 155 Kelvin. However, this reaction was not expected to occur at mid-latitudes, where temperatures are much warmer.

"The fact that HCl at mid-latitudes dropped by this unprecedented amount was to me kind of a danger signal," Solomon says.

She wondered: What if HCl could also interact with smoke particles, at warmer temperatures and in a way that released chlorine to destroy ozone? If such a reaction was possible, it would explain the imbalance of molecules and much of the ozone depletion observed following the Australian wildfires.

Smoky drift

Solomon and her colleagues dug through the chemical literature to see what sort of organic molecules could react with HCl at warmer temperatures to break it apart.

"Lo and behold, I learned that HCl is extremely soluble in a whole broad range of organic species," Solomon says. "It likes to glom on to lots of compounds."

The question then, was whether the Australian wildfires released any of those compounds that could have triggered HCl's breakup and any subsequent depletion of ozone. When the team looked at the composition of smoke particles in the first days after the fires, the picture was anything but clear.

"I looked at that stuff and threw up my hands and thought, there's so much stuff in there, how am I ever going to figure this out?" Solomon recalls. "But then I realized it had actually taken some weeks before you saw the HCl drop, so you really need to look at the data on aged wildfire particles."

When the team expanded their search, they found that smoke particles persisted over months, circulating in the stratosphere at mid-latitudes, in the same regions and times when concentrations of HCl dropped.

"It's the aged smoke particles that really take up a lot of the HCl," Solomon says. "And then you get, amazingly, the same reactions that you get in the ozone hole, but over mid-latitudes, at much warmer temperatures."

When the team incorporated this new chemical reaction into a model of atmospheric chemistry, and simulated the conditions of the Australian wildfires, they observed a 5 percent depletion of ozone throughout the stratosphere at mid-latitudes, and a 10 percent widening of the ozone hole over Antarctica.

The reaction with HCl is likely the main pathway by which wildfires can deplete ozone. But Solomon guesses there may be other chlorine-containing compounds drifting in the stratosphere, that wildfires could unlock.

Read more at Science Daily

20,000 premature US deaths caused by human-ignited fires each year

Over 80% of premature deaths caused by small smoke particles in the United States result directly from human-ignited fires. This is the outcome of a study published today in IOP Publishing's journal Environmental Research Letters.

The new study, led by researchers at the Massachusetts Institute of Technology, analyses the impact of smoke particles on air quality in the United States. Their research shows that human-ignited fires account for more than 67% of small smoke particles called PM2.5 in the United States. These particles are known to degrade air quality, causing respiratory illnesses and premature death.

The level of fire activity in the US is on the rise. The research team estimate that smoke from human-ignited fires was responsible for 20,000 premature deaths in 2018 alone, a year with a high frequency of fire events -- a substantial portion of which were associated with human ignitions such as agricultural and human lit fires. This is 270% more than there were in 2003, when there was a low frequency of fire events. The research highlights that during high fire activity years, there are much higher concentrations of smoke PM2.5 in the air.

Dr Therese Carter, lead author of the study, said: "Fires not only threaten human lives, infrastructure, and ecosystems, but they are also a major cause for concern in terms of air quality. High levels of smoke exposure can negatively impact human health resulting in conditions such as respiratory infections, lung cancer, heart disease and even premature births. Our results show that a large and significant portion of harmful smoke particles result directly from human-lit fires."

The team used the Global Fire Emissions Database to quantify agricultural fire emissions, then classify these fires into two categories: human vs. natural ignition. Applying a chemical transport model, they simulate the concentration of smoke particles across the United States, concluding that a significant portion of PM2.5 in the US results from human-ignited fires and thus has the potential to be managed.

To limit the devastating effects of pollution from small smoke particles, the team recommends an ignition-focused approach. State agencies can implement management plans to restrict the ignition of agricultural fires to periods when weather conditions would minimise health impacts. However, human-ignited wildfires are much harder to manage due to their sporadic and unplanned nature.

Read more at Science Daily

Pacific Northwest wildfires alter air pollution patterns across North America

Increasingly large and intense wildfires in the Pacific Northwest are altering the seasonal pattern of air pollution and causing a spike in unhealthy pollutants in August, new research finds. The smoke is undermining clean air gains, posing potential risks to the health of millions of people, according to the study.

The research, led by scientists at the National Center for Atmospheric Research (NCAR), found that levels of carbon monoxide -- a gas that indicates the presence of other air pollutants -- have increased sharply as wildfires spread in August. Carbon monoxide levels are normally lower in the summer because of chemical reactions in the atmosphere related to changes in sunlight, and the finding that their levels have jumped indicates the extent of the smoke's impacts.

"Wildfire emissions have increased so substantially that they're changing the annual pattern of air quality across North America," said NCAR scientist Rebecca Buchholz, the lead author. "It's quite clear that there is a new peak of air pollution in August that didn't used to exist."

Although carbon monoxide generally is not a significant health concern outdoors, the gas indicates the presence of more harmful pollutants, including aerosols (airborne particulates) and ground-level ozone that tends to form on hot summer days.

The research team used satellite-based observations of atmospheric chemistry and global inventories of fires to track wildfire emissions during most of the past two decades, as well as computer modeling to analyze the potential impacts of the smoke. They focused on three North American regions: the Pacific Northwest, the central United States, and the Northeast.

Buchholz said the findings were particularly striking because carbon monoxide levels have been otherwise decreasing, both globally and across North America, due to improvements in pollution-control technologies.

The study was published this week in Nature Communications. The research was funded in part by the U.S. National Science Foundation, NCAR's sponsor. The paper was co-authored by researchers from the University of Colorado, Boulder; Columbia University; NASA; Tsinghua University; and Colorado State University.

Increasing impacts on air pollution

Wildfires have been increasing in the Pacific Northwest and other regions of North America, due to a combination of climate change, increased development, and land use policies. The fires are becoming a larger factor in air pollution, especially as emissions from human activities are diminishing because of more efficient combustion processes in motor vehicles and industrial facilities.

To analyze the impacts of fires, Buchholz and her collaborators used data from two instruments on the NASA Terra satellite: MOPITT (Measurements of Pollution in the Troposphere), which has tracked carbon monoxide continually since 2002; and MODIS (Moderate Resolution Imaging Spectrometer), which detects fires and provides information on aerosols. They also studied four inventories of wildfire emissions, which rely on MODIS data.

The scientists focused on the period from 2002, the beginning of a consistent and long-term record of MOPPIT data, to 2018, the last year for which complete observations were available at the time when they began their study.

The results showed an increase in carbon monoxide levels across North America in August, which corresponded with the peak burning season of the Pacific Northwest. The trend was especially pronounced from 2012 to 2018, when the Pacific Northwest fire season became much more active, according to the emissions inventories. Data from the MODIS instrument revealed that aerosols also showed an upward trend in August.

To determine whether the higher pollution levels were caused by the fires, the scientists eliminated other potential emission sources. They found that carbon monoxide levels upwind of the Pacific Northwest, over the Pacific Ocean, were much lower in August -- a sign that the pollution was not blowing in from Asia. They also found that fire season in the central U.S. and the Northeast did not coincide with the August increase in pollution, which meant that local fires in those regions were not responsible. In addition, they studied a pair of fossil fuel emission inventories, which showed that carbon monoxide emissions from human activities did not increase in any of the three study regions from 2012 to 2018.

"Multiple lines of evidence point to the worsening wildfires in the Pacific Northwest as the cause of degraded air quality," Buchholz said. "It's particularly unfortunate that these fires are undermining the gains that society has made in reducing pollution overall."

Risks to human health

The findings have implications for human health because wildfire smoke has been linked to significant respiratory problems, and it may also affect the cardiovascular system and worsen pregnancy outcomes.

Buchholz and her co-authors used an NCAR-based computer model, the Community Atmosphere Model with a chemistry component, to simulate the movement of emissions from the Pacific Northwest fires and their impact on carbon monoxide, ozone, and fine particulate matter. They ran the simulations on the Cheyenne supercomputer at the NCAR-Wyoming Supercomputing Center. The results showed the pollutants could affect more than 130 million people, including about 34 million in the Pacific Northwest, 23 million in the Central U.S., and 72 million in the Northeast.

Although the study did not delve deeply into the health implications of the emissions, the authors looked at respiratory death rates in Colorado for the month of August from 2002 to 2011, compared with the same month in 2012 to 2018. They chose Colorado, located in the central U.S. region of the study, because respiratory death rates in the state were readily obtainable.

They found that Colorado respiratory deaths in August increased significantly during the 2012-2018 period, when fires in the Pacific Northwest -- but not in Colorado -- produced more emissions in August.

Read more at Science Daily

Older wildfire smoke plumes can affect climate

Aerosols carried in wildfire smoke plumes that are hundreds of hours old can still affect climate, according to a study out of the University of California, Davis.

The research, published in the journal Environmental Science and Technology, suggests that wildfire emissions even 10 days old can affect the properties of aerosols -- suspended liquid or particles that are key to cloud formation.

Research in aerosols and particulate matter pollution related to wildfires has most often focused on the early hours of smoke plumes, not several days later after smoke has traveled to other areas.

Enhancing modeling

This research helps fill in a knowledge gap and can inform future predictions about the climate and atmospheric effects of wildfire over the lifetime of aerosols, particularly in rural or pristine areas with relatively clean air, said Qi Zhang, an environmental toxicology professor and lead author of the study.

"These parameters are really useful for atmospheric and chemical models," she said. "It's a really important component to solving the effects on climate. To capture those characteristics is super critical."

Zhang, Ph.D. student Ryan Farley and others spent time in 2019 at the Mount Bachelor Observatory atop a volcanic mountain in Oregon. That year was relatively calm in terms of wildfire, but smoke plumes and aerosols were still observed. Some were at least 10 days old and came from as close as Northern California and as far as Siberia, Russia.

The properties and chemical composition of aerosols can do a number of things: scatter or absorb solar radiation affecting temperature, seed clouds to produce rain or snow, or change the reflectivity of clouds -- all of which affect climate.

Aerosol properties change with age

Scientists found that particulate matter concentrations were low, but oxidized organic aerosols from burning biomass -- such as trees, grasses and shrubs -- were detected throughout the samples.

The aerosols, which have a life cycle of about two weeks, were larger in aged samples compared to those found shortly after a fire starts.

"The properties of the smoke determine the effects on the climate," Zhang said. "The really aged aerosols can behave very differently than the fresh ones. You want to capture these aerosols over the lifetime to properly account for the effects."

Aerosols in the background

Older aerosols produced by wildfires can be present but not obvious and still affect climate.

"It's not something you just notice but it's in the background," she said.

Knowing that information becomes ever more important as "biomass burning has become more and more frequent," Zhang said.

Read more at Science Daily

Early humans placed the hearth at the optimal location in their cave -- for maximum benefit and minimum smoke exposure

A groundbreaking study in prehistoric archaeology at Tel Aviv University provides evidence for high cognitive abilities in early humans who lived 170,000 years ago. In a first-of-its kind study, the researchers developed a software-based smoke dispersal simulation model and applied it to a known prehistoric site. They discovered that the early humans who occupied the cave had placed their hearth at the optimal location -- enabling maximum utilization of the fire for their activities and needs while exposing them to a minimal amount of smoke.

The study was led by PhD student Yafit Kedar, and Prof. Ran Barkai from the Jacob M. Alkow Department of Archaeology and Ancient Near Eastern Cultures at TAU, together with Dr. Gil Kedar. The paper was published in Scientific Reports.

Yafit Kedar explains that the use of fire by early humans has been widely debated by researchers for many years, regarding questions such as: At what point in their evolution did humans learn how to control fire and ignite it at will? When did they begin to use it on a daily basis? Did they use the inner space of the cave efficiently in relation to the fire? While all researchers agree that modern humans were capable of all these things, the dispute continues about the skills and abilities of earlier types of humans.

Yafit Kedar: "One focal issue in the debate is the location of hearths in caves occupied by early humans for long periods of time. Multilayered hearths have been found in many caves, indicating that fires had been lit at the same spot over many years. In previous studies, using a software-based model of air circulation in caves, along with a simulator of smoke dispersal in a closed space, we found that the optimal location for minimal smoke exposure in the winter was at the back of the cave. The least favorable location was the cave's entrance."

In the current study the researchers applied their smoke dispersal model to an extensively studied prehistoric site -- the Lazaret Cave in southeastern France, inhabited by early humans around 170,000 to 150,000 years ago. Yafit Kedar: "According to our model, based on previous studies, placing the hearth at the back of the cave would have reduced smoke density to a minimum, allowing the smoke to circulate out of the cave right next to the ceiling. But in the archaeological layers we examined, the hearth was located at the center of the cave. We tried to understand why the occupants had chosen this spot, and whether smoke dispersal had been a significant consideration in the cave's spatial division into activity areas."

To answer these questions, the researchers performed a range of smoke dispersal simulations for 16 hypothetical hearth locations inside the 290sqm cave. For each hypothetical hearth they analyzed smoke density throughout the cave using thousands of simulated sensors placed 50cm apart from the floor to the height of 1.5m.

To understand the health implications of smoke exposure, measurements were compared with the average smoke exposure recommendations of the World Health Organization. In this way four activity zones were mapped in the cave for each hearth: a red zone which is essentially out of bounds due to high smoke density; a yellow area suitable for short-term occupation of several minutes; a green area suitable for long-term occupation of several hours or days; and a blue area which is essentially smoke-free.

Yafit and Gil Kedar: "We found that the average smoke density, based on measuring the number of particles per spatial unit, is in fact minimal when the hearth is located at the back of the cave -- just as our model had predicted. But we also discovered that in this situation, the area with low smoke density, most suitable for prolonged activity, is relatively distant from the hearth itself.

Early humans needed a balance -- a hearth close to which they could work, cook, eat, sleep, get together, warm themselves, etc. while exposed to a minimum amount of smoke. Ultimately, when all needs are taken into consideration -- daily activities vs. the damages of smoke exposure -- the occupants placed their hearth at the optimal spot in the cave."

The study identified a 25m2 area in the cave which would be optimal for locating the hearth in order to enjoy its benefits while avoiding too much exposure to smoke. Astonishingly, in the several layers examined by in this study, the early humans actually did place their hearth within this area.

Prof. Barkai concludes: "Our study shows that early humans were able, with no sensors or simulators, to choose the perfect location for their hearth and manage the cave's space as early as 170,000 years ago -- long before the advent of modern humans in Europe. This ability reflects ingenuity, experience, and planned action, as well as awareness of the health damage caused by smoke exposure. In addition, the simulation model we developed can assist archaeologists excavating new sites, enabling them to look for hearths and activity areas at their optimal locations."

Read more at Science Daily

Forest fires linked to low birth weight in newborns

Women exposed to smoke from landscape fires during pregnancy are more likely to give birth to babies with low or very low birth weights, according to findings published in eLife.

The study is the first to report a link between low birth weight and exposure to fire smoke in low and middle-income countries (LMICs), where 90% of low birth weight infants are born and landscape fires are prevalent.

Landscape fires, such as wildfires, tropical deforestation fires and agricultural biomass burning, play an important role in maintaining terrestrial ecosystems. Yet, landscape fire smoke is triggering a costly and growing global public health problem, causing recurrent episodes of pollution mostly affecting LMICs.

Previous studies have shown that exposure to fire smoke during pregnancy is linked to low birth weight, which itself is a public health problem in LMICs. Reducing the risk of low birth weight is one of the World Health Organization's global targets for 2025.

"Babies with low birth weights are at higher risk of a range of diseases in later life compared to normal weight newborns," explains co-first author Jiajianghui Li, a PhD student at the Institute of Reproductive and Child Health, School of Public Health Science Centre, Peking University, China. "Several studies have shown the effects of landscape fire smoke on acute lung and heart conditions, but the health impacts of these pollutants on susceptible pregnant women are not well known. We wanted to explore the association between birth weight and exposure to fire source pollution across several countries and over a long time period."

The researchers conducted a case-control study in 54 LMICs where they matched 108,137 groups of siblings to their mothers. They used surveys conducted by the US Agency for International Development between 2000 and 2014 to find out information about sibling birth weights and other health and demographic factors. They then assessed exposure to landscape fire pollutants using data on fire emissions from the Global Fire Emission Database and a model that converted this data into ground-surface concentrations of particulate matter in different regions.

Their analysis showed that an increase in exposure of one microgram per cubic metre of fire-sourced particulate matter was associated with a 2.17-gram reduction in birth weight. "The effect was even more pronounced when we looked at whether exposure to fire smoke was linked to low or very low birth weight; for every microgram per cubic metre increase in particulate matter exposure, the risks of low and very low birth weight increased by around three and 12 per cent, respectively," says co-first author Tianjia Guan, an assistant professor at the Department of Health Policy, School of Health Policy and Management, Chinese Academy of Medical Sciences and Peking Union Medical College, China.

The researchers found that very low birth weight was most strongly linked to the pollution. To find out why, they developed a model that looked at the average birth weight of infants within single families. Newborns in families that had lower birth weights on average were more susceptible to the risks of fire smoke pollution than those who had moderate baseline birthweights. "This suggests that other factors affecting maternal and foetal health, such as nutrition or maternal employment status, might make mothers and their developing infants even more susceptible to the risks of pollution," says co-first author Qian Guo, a PhD student at the School of Energy and Environmental Engineering, University of Science and Technology, China.

Read more at Science Daily

When the western US burns, the east also gets sick

While most of the largest U.S. wildfires occur in the Western U.S., almost three-quarters of the smoke-related deaths and visits to the emergency room for asthma occur east of the Rocky Mountains.

Smoke exposure, whether from wildfires or local burning, contributes to health problems across the U.S., but the impacts vary by region. A new study finds that smoke contributes to a larger percentage of health problems in the West, but affects greater numbers of people in the East -- possibly when they aren't even aware of the smoky air.

The new study was published in GeoHealth, AGU's journal investigating the intersection of human and planetary health for a sustainable future.

In the West, where population density is generally lower and smoke concentrations are typically higher, smoke played a larger role in the number of asthma complaints and ER visits, contributing to more than 1% of annual visits in some years. In the East, with its high population density and lower smoke concentrations, there were a higher number of visits overall, even though a smaller percentage were related to smoke (0.3% to 0.6%).

The researchers estimate that long-term smoke exposure results in about 6,300 extra deaths each year, with the highest numbers occurring in the most populous states. Only 1,700 of those deaths occurred in the West.

Fires throw tremendous amounts of pollutants into the air, including toxic gases and soot. Smoke contains tiny particles smaller than 2.5 microns, called PM2.5, that enter the lungs and contribute to multiple health problems. Short-term exposure to PM2.5 from smoke is linked to respiratory health problems, like asthma attacks, and the long-term effects of PM2.5 from smoke are not fully understood. Research on PM2.5 from urban pollution suggests that exposure is linked to lung cancer, heart disease and an overall higher chance of death.

"Large wildfires are projected to increase in frequency and burned area in the Western U.S. Because of that, and projected decreases in urban-sourced PM2.5, fires are expected to become the dominant source of PM2.5 in the U.S. by the end of the century," said atmospheric scientist and first author Katelyn O'Dell. O'Dell was formerly a graduate student at Colorado State University but is now a postdoctoral researcher at George Washington University. "We wanted to study the impacts of wildfire smoke specifically on health so we can better prepare for that future, when we expect to have more smoke in our lives."

O'Dell collaborated with epidemiologists at Colorado State University to perform a health impact assessment. The researchers estimated the fraction of asthma ER visits and hospitalizations resulting from PM2.5 in smoke across the country from 2006 to 2018. They used existing data on asthma hospital visits and daily local estimates of PM2.5 based on readings from instruments at ground level and satellite data showing the location of smoke in the atmosphere.

The new study also included the first analysis of the health impacts of 18 hazardous air pollutants (HAPs) present in smoke, such as formaldehyde and benzene. The researchers determined that HAPs are likely a less important but more uncertain factor than PM2.5 in the health problems caused by smoke exposure.

As smoke pollution is likely to increase, the researchers argue that the U.S. needs better national smoke forecasting and alerts so that people in downwind regions know when to take precautions like wearing a mask, limiting time outside and using indoor air purifiers.

"We talk about smoke in the West so much, but we don't often talk about smoke in the East," O'Dell said. "I wonder if there's a lack of awareness because you think, 'Oh, that's a Western problem.'"

O'Dell emphasized that their study didn't determine the source of the smoke affecting each region and that local burning and Canadian fires also contribute to smoky air in the Eastern U.S. She said that establishing the source of the smoke impacting health in each region is an important next step.

Tarik Benmarhnia, a climate change epidemiologist at the University of California, San Diego, who was not involved in the study, agreed that we need better smoke warning systems, especially for farm workers and others who labor outside. He pointed out that while smoke plumes impact entire regions, they don't affect all residents equally. Age, race, ethnicity, exposure to other types of air pollution -- such as from traffic -- and pre-existing health conditions can all put a person at higher risk of developing health problems from smoke. He said that future research should investigate these disparities.

Read more at Science Daily

Decades after toxic exposure, 9/11 first responders may still lower their risk of lung injury

Losing weight and treating excess levels of fat in the blood may help prevent lung disease in firefighters exposed to dangerous levels of fine particles from fire, smoke, and toxic chemicals on Sept. 11, 2001, a new study shows. Experts have long feared that this exposure would later lead to lung disease in first responders. High body mass index (BMI), an indicator of obesity, and exposure to the highest levels of toxins from the attack on the World Trade Center were the two greatest risk factors for lowered lung function, according to the study authors.

After two decades of research analyzing thousands of first responders, a new investigation led by researchers at NYU Grossman School of Medicine identified a cluster of five factors that predicted lung disease in these patients. Along with excess body fat, the combination of insulin resistance, high blood pressure, and increased levels of sugar and cholesterol in the blood are components of so-called metabolic syndrome, a group of medical issues known to raise the risk of heart disease, stroke, and diabetes.

Adjusting at least one of these factors, the study investigators found, can greatly lower the risk of firefighters' developing lung disease within five years, even 20 years after toxic exposures at Ground Zero. For example, for a male firefighter of average height, a 7-pound weight loss could decrease his risk for lung injury by 20 percent.

"Our findings should reassure World Trade Center first responders that there are steps they can take to protect their lungs even decades after exposure," says study co-lead author Sophia Kwon, DO, MPH. Kwon is a fellow in the Division of Pulmonary, Critical Care, and Sleep at NYU Langone Health.

In work presented earlier this year on 100 overweight 9/11 firefighters, the team found that placing patients on a calorie-restricted Mediterranean diet featuring unrefined grains, olive oil, fruits, and fish reduced their risk of lung disease. Those following the regimen for six months lost nearly 2 BMI points (from an average BMI of about 33 to an average of 31) and had fewer signs of lung disease than they had reported before the study period.

"These results offer firefighters a concrete way to lose weight and achieve the lung-health benefits predicted by our risk model," says study co-lead author George Crowley, BA, a predoctoral fellow at NYU Langone.

Experts had previously understood that first responders who developed metabolic syndrome shortly after 9/11 were more likely to have higher rates of asthma. However, lung injury risks for a firefighter whose metabolic syndrome instead appeared later in life remained unclear until now.

The new study, publishing Sept. 2 in the American Journal of Respiratory and Critical Care Medicine, is part of what is likely the longest-running and most thorough exploration of the impact of metabolic syndrome on lung injury in 9/11 firefighters, according to the study authors. In addition, the investigation is the first to date to quantify how adjusting one or more of these risk factors changes lung disease risk.

For the investigation, the research team analyzed 20 years of data from more than 5,700 firefighters active on 9/11, of whom 1,475 later developed lung disease. Along with BMI, the data collected included smoking history, and whether they had served at the World Trade Center in early morning when pollutant exposure was at its peak.

"The lessons from our investigation can be applied not only to firefighters but to the millions of city dwellers exposed to air pollution on a daily basis," says study senior author and pulmonologist Anna Nolan, MD. "They should be aware that while their environment poses real health risks, they may still minimize their risk of lung disease even if they cannot change their exposure."

Nolan, a professor in the Departments of Medicine and Environmental Health at NYU Langone, cautions that while promising, the Mediterranean diet investigation only examined a small, specific group.

As a result, the research team next plans to expand the study to determine whether the diet could benefit a more diverse population who have been similarly exposed to urban pollutants. They also plan to explore how metabolic syndrome may affect other measures of lung function like asthma, says Nolan.

Read more at Science Daily

How people respond to wildfire smoke

As wildfires become commonplace in the western U.S. and around the world, checking the daily air quality warning has become as routine as checking the weather. But what people do with that data -- whether it drives them to slip on a mask before stepping outside or seal up their homes against smoke -- is not always straightforward or rational, according to new Stanford research.

In a case study of Northern California residents, Stanford researchers explored the psychological factors and social processes that drive responses to wildfire smoke. The research, which ultimately aims to uncover approaches for helping people better protect themselves, shows that social norms and social support are essential for understanding protective health actions during wildfire smoke events. The findings appeared this month in the journal Climate Risk Management.

"It's important to understand how people behave so that public health communications professionals can potentially intervene and promote safer behavior that mitigates risk," said lead study author Francisca Santana, a PhD student in the Emmett Interdisciplinary Program in Environment and Resources (E-IPER). "This kind of qualitative work is a first step so that we can learn how people are using information and interacting to make decisions. We can then look at where there might be leverage points or opportunities to promote more protective behavior."

Exposure to wildfire smoke can irritate the lungs, cause inflammation, impact the immune system and increase susceptibility to lung infections, including the virus that causes COVID-19, according to the Centers for Disease Control and Prevention. While other studies have examined how people respond to evacuation orders, little has been done to understand what's happening with wildfire smoke exposure if people don't -- or can't -- leave the area, according to senior study author Gabrielle Wong-Parodi, an assistant professor of Earth system science at Stanford's School of Earth, Energy & Environmental Sciences (Stanford Earth).

"It resonated with me, the things that people were doing to try to protect themselves in the absence of access to effective ways to reduce their wildfire smoke exposure," Wong-Parodi said, referring to a resident who breathed through a wet bandana in an attempt to filter out toxic smoke particles. "It's urgent that we come up with strategies that are realistic for what people are going through."

Study authors Santana and David Gonzalez, who worked on the study as a PhD student at Stanford, interviewed residents across age, race and income demographics who were affected by wildfire smoke from the 2018 Camp Fire that destroyed Paradise, California, and subsequent fires in 2019 in Fresno, Santa Clara and Sacramento counties.

They found that individuals responded to wildfire smoke events in three main ways: interpreting information together, protecting vulnerable others and questioning protective actions. Their responses were influenced not only by the Air Quality Index (AQI) but also by what they were personally experiencing -- whether they smelled, saw or tasted smoke in the air.

Just as important were the social factors at play, the researchers found. "Social norms and social support were really influencing how people chose to act on their perceptions of threat," Santana said. "For example, a lot of people talked about observing others wearing masks, and in some cases that observation was enough for them to act by wearing a mask themselves."

Their discussions revealed that the shared rules or standards of behavior within a social group -- social norms -- were a common pathway driving behavior change, in addition to the act of assisting or comforting others within your social group -- social support.

"There were only a handful of people who described looking at the AQI and then changing their behavior based on just that -- it was almost always a conversation they were having with one another," Santana said. "It was very much a social exercise of making sense of limited information or information that was not at the right scale for their community."

The study provides a framework for better understanding wildfire smoke responses by examining social processes while acknowledging that cultural and political contexts, as well as factors like demographics, health status and previous exposure to smoke and air pollution, may also influence individual behaviors.

In the western U.S., climate change has contributed to the risk and extent of wildfires, bringing smoke to regions like the Bay Area, which has historically been less affected than the rest of the state. In some cases, the researchers found that residents were unable to protect themselves because they couldn't access N95 masks or air purifiers or properly seal their homes.

"This research is also important for epidemiologists trying to understand how wildfire smoke affects health," said Gonzalez, who is now a postdoctoral researcher at the University of California, Berkeley. "This can help us to look at disparities in who's exposed to smoke and whether that leads to poorer health for some populations."

As these events become more common, there could be an opportunity to find policy synergies that help prepare communities for future smoke events, according to the co-authors. For example, programs that are designed to improve household comfort and increase energy efficiency could also include measures to reduce smoke intrusion during wildfire smoke events, Wong-Parodi suggested.

Some of the interviews revealed that residents simply didn't know what to do while experiencing a novel extreme event. But even that revealed how processing uncertainty is a social exercise, not just a cognitive one.

Read more at Science Daily

Californian smoke drifted as far as Europe in 2020 and caused heavy clouding of sun

The smoke from the extreme forest fires on the US West Coast in September 2020 travelled over many thousands of kilometres to Central Europe, where it continued to affect the atmosphere for days afterwards. A comparison of ground and satellite measurements now shows: The forest fire aerosol disturbed the free troposphere over Leipzig in Germany as never before. An evaluation by an international research team led by the Leibniz Institute for Tropospheric Research (TROPOS) revealed an extraordinary optical thickness on 11 September 2020, which attenuated sunlight by a third. The study, published in Geophysical Research Letters, is the first publication to show that ESA's novel Aeolus satellite can not only reliably measure global wind profiles but also aerosols in the atmosphere as it was shown by comparing Aeolus measurements with lidar measurements from the ground. The Centre National de Recherches Météorologiques (CNRM) of the University of Toulouse, the German Aerospace Center (DLR) and the European Space Agency (ESA) were involved in the study.

Since August 2018, a new type of research satellite has been orbiting the Earth, named after a Greek wind god -- Aeolus. The aim of Aeolus is to actively measure wind from space and thus improve weather forecasting. On board of this satellite of the European Space Agency (ESA) is the "Atmospheric Laser Doppler Instrument" (ALADIN), a high-performance laser. ALADIN is the first instrument in space that can actively measure vertical profiles of wind speed. It uses the principle of a light radar (short: Lidar from "LIght Detection And Ranging"). A signal is emitted and the reflection provides information about location and distance. The Doppler effect is then used to measure the wind speed at different heights in the atmosphere. To validate the laser measurements in space, they are compared with laser measurements from the ground. Several research groups from Germany are involved in this effort within the framework of the EVAA initiative (Experimental Validation and Assimilation of Aeolus observations). TROPOS, for example, measures with its lidar devices every Friday evening and Sunday morning when the Aeolus satellite flies over Leipzig. The data from ground and space can then be compared. On 11 September 2020, this resulted in the rare constellation that the extraordinary plume of smoke from the Californian forest fires could be measured over Leipzig simultaneously from ground and from space.

"Using revolutionary laser technology, Aeolus is currently the only satellite in the world that can measure profiles of horizontal wind speed as well as the backscatter and extinction of aerosols and clouds independently. The satellite thus provides valuable information on the radiative properties of these smoke aerosols," emphasises Dr Sebastian Bley of TROPOS, who has been involved in the Aeolus project at the European Space Agency's (ESA) ESRIN research centre for the past three years. "It is expected that this unique configuration will contribute to improved predictions of such global smoke dispersion but also of weather in general."

In September 2020, the heat from the extreme forest fires on the US West Coast transported the smoke to high altitudes. Once high up, it was then transported with the jet stream across North America and the Atlantic to Europe. In Leipzig, Germany, the smoke layer appeared at an altitude of around 12 kilometres on the morning of 11.09.2020 and sank to an altitude of around 5 kilometres in the course of the day. This is shown by the data from the PollyXT lidar at TROPOS. Lidar measurements in Leipzig confirmed the strong attenuation of the direct sunlight on this Friday: "It was -- measured by the Aerosol Optical Thickness (AOT) -- the strongest influence of forest fire aerosol on the free troposphere above Leipzig ever observed since the beginning of regular lidar observations in 1997," reports Dr Holger Baars from TROPOS, "The free troposphere is the region of the atmosphere in which the weather takes place but the direct influence from the ground is low. We were able to estimate an average mass concentration of forest fire aerosol of 8 micrograms per cubic metre between 4 and 11 km altitude. At the peak it was even 22 micrograms per cubic metre -- that's quite remarkable for these altitudes." Saturday and Sunday were hazy days despite cloudless skies. The UV index of the Federal Office for Radiation Protection (BfS), among others, also showed how strongly the smoke layers dampened solar radiation in Saxony: the TROPOS station in Melpitz near Torgau registered about a quarter less UV radiation at noon on 12 September 20 than would have been possible under clear sky. The unusual state of the atmosphere was particularly striking at sunset with a distinctive milky-yellow light.

The researchers were able to confirm the origin of the smoke using a computer model: The backward simulation proves that the air masses that arrived at noon on 11 September at an altitude of 8.5 km above Leipzig originated from the west coast of North America, where intense fires took place days before. The frequency and intensity of fires in California continued to increase during the first week of September as satellite images show. Slightly weaker fires were observed in Oregon, Washington and Montana. "Due to the prevailing winds, the travel time of the smoke from the US West Coast to Europe was only about 3 to 4 days. The air masses even made the approximately 3000 kilometres across the Atlantic Ocean between Newfoundland and Ireland at high speed in only one day (9 September)," explains Martin Radenz from TROPOS.

Read more at Science Daily