Preadolescents exposed to high levels of air pollution in their first years of life display changes in brain connectivity

Higher exposure to air pollution is associated with higher functional brain connectivity among several brain regions in preadolescents, while exposure to traffic noise was not, according to a study led by ISGlobal, an institution supported by "la Caixa" Foundation. The findings also identify the first years of life as the most sensitive period of exposure to air pollution.

Traffic-related air pollution and noise are affecting an increasing number of people worldwide. "We already know that children are particularly vulnerable to the effect of these exposures, because of their immature metabolism and developing brain," says ISGlobal researcher and senior author Mónica Guxens. In fact, several studies by Guxens and others have found an association between exposure to traffic-related air pollution during early childhood and alterations in the brain structure.

In this study, the research team used magnetic resonance imaging (MRI) to explore whether higher exposure to air pollution or noise could also be associated with possible alterations in brain connectivity (i.e. the way in which different brain regions interact). "The use of MRI has opened up new possibilities in epidemiological research for investigating the structure and the functioning of the brain," says Guxens.

The researchers used data of 2,197 children from the Generation R Study, born between April 2002 and Jan 2006 and living in Rotterdam, the Netherlands. Using land use models, they estimated levels of nitrogen oxides (NOx and NO2) and particulate matter (PM) at the participants' homes at different time periods: during pregnancy, from birth to 3 years, from 3 to 6 years, and from 6 years of age to the age at which the MRI scan was performed. Noise levels due to traffic road were estimated using existing noise maps. Between 9 and 12 years of age, the participants were invited to undergo an MRI scan in the resting state (i.e. with no external stimuli).

The findings show that higher exposures to NO2 and PM2.5 absorbance (an indicator of black carbon particles) from birth to 3 years, and to NOx from 3 to 6 years of age were associated with higher functional brain connectivity among several brain regions in the preadolescents. The associations were identified in brain areas predominantly involved in two networks that have strongly opposing functions: the task negative (or "default-mode") network tends to be activated in resting conditions and the task positive network tends to be activated during tasks that demand attention. "We still have to understand the consequences of this increased activity of both networks in resting conditions, but for now we can say that the brain connectivity in children exposed to higher levels of air pollution is different from what we would expect," says Laura Pérez-Crespo, first author of the study.

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New online tool to help residents reduce the impact of traffic-related air pollution

Researchers at the University of Surrey have released a new online tool to help schools, hospitals and residents understand and reduce the impact of traffic-related air pollution.

The Hedge Design for the Abatement of Traffic Emissions (HedgeDATE) -- online tool allows users to describe their environment -- such as a road with buildings on one side -- and then recommends actions citizens can take to improve its air quality.

For example, HedgeDATE advises that a resident living in a shallow street canyon should install hedges and a green wall; the tool can also give more detailed information on the species of plants suitable for different locations.

The development of HedgeDATE builds on years of research and public engagement work by the University of Surrey's Global Centre for Clean Air Research (GCARE). HedgeDATE grew out of workshops on air pollution mitigation conducted with local communities as part of Guildford Living Lab.

Professor Prashant Kumar, founding director of GCARE and founder of the Guildford Living Lab at the University of Surrey, said: "The best use of research is for public benefit. However, this poses the challenge of translating complex science into simple, evidence-based actions. At GCARE, we proactively engage with the community and produce co-designed solutions such as HedgeDATE. Soon, when the world is back on its feet after the pandemic, we will need to come to terms with the air pollution and climate change crisis.

"HedgeDATE is about giving ordinary people -- our schools, hospitals and councils -- easy-to-use tools that can inspire them to make a real difference to the quality of the air they breathe."

Justine Fuller, co-author of the paper on HedgeDATE from Guildford Borough Council, said: "We have been collaborating with Professor Kumar's team for many years. The HedgeDATE tool is an excellent means of engaging the public on air pollution issues. It has been a pleasure to support this project and will look forward to sharing this with the interested user groups."

Dr Stuart Cole, another co-author from Oxfordshire County Council, said: "We're proud to be collaborators on the HedgeDATE project. HedgeDATE will be a useful educational tool for councils, schools, other organisations and members of the public to consult when planning green areas for improved air quality."

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