Despite big gains over the last decades to reverse the risks of climate change, many people across the globe still live in areas with high levels of pollution. This, say researchers and environmental experts, have a detrimental effect not only on their physical, but also mental health.
It has now been scientifically proved that exposure to polluted water and air can lead to brain inflammation, the body’s natural, protective response to fight harmful contaminants. This leads to brain-related impairment and disease.
The brain, which starts to develop mere weeks after conception, continues to change throughout life, facing the threat of many environmental hazards. The effects of lead and mercury on the brain had been known for decades and continue present a large global health problem. Many pesticides are neurotoxic but yet remain available for use. Recent evidence also suggests that fluoride, a compound used in public water supplies to reduce tooth decay, may also be neurotoxic. Even the air humans breathe is associated with an increase in the risk of many brain-related conditions.
Scientists had established how environmental contaminants and air pollution are linked to chronic medical conditions such as asthma, chronic obstructive pulmonary disease (COPD) and heart diseases. The brain is not immune to environmental contaminants and there is increasing evidence that air pollution is linked to conditions including autism spectrum disorders, dementia and lower cognition.
“You only have one chance to develop a brain — you can’t go back and do it over or get a transplant,” says Prof Philippe Grandjean, professor of environmental medicine at the University of Southern Denmark and professor of environmental health at the Harvard School of Public Health.
Neurodevelopmental and neurodegenerative disorders have individual unique features, but many share much of the same underlying brain tissue changes which polluted air may exacerbate. “The risk of air pollution on the brain is a much broader risk factor than we’ve given it credit for,” says Deborah Cory-Slechta, professor of environmental medicine at the University Of Rochester Medical Centre.
Air pollution can include industrial emissions and pesticides which had been identified as associated with brain-related conditions. Growing evidence suggests that air pollution may more deeply affect long-term human health, behaviour and functioning than originally thought. Experts say this motivates the need for science-driven regulations and policies to minimise exposure.
Brain damage, whether in children or adults, can have a lifelong impact.
“The main concern is really that even minor dysfunction of the brain can have dramatic consequences,” Grandjean says. “You can live a normal life with decreased liver function and you can donate a kidney for transplantation, and it won’t affect your health. But for the brain, every IQ point is important.”
Many animal studies have shown that air pollution negatively impacts animal brains as well. Although animal studies do not necessarily mean the same findings translate to human beings, these are still controlled studies providing strong evidence that air pollution negatively affects the brain.
What can we do?
California recently passed legislation requiring all cars sold in the state to be electric by 2035. The Regional Greenhouse Gas Initiative, a cooperative effort involving a growing number of north-eastern and Mid-Atlantic States to reduce greenhouse gas emissions, had already prevented hundreds of cases of childhood illnesses and saved hundreds of millions of dollars in costs. For scientists and public health experts, prevention makes the most sense.
The effects of ultrafine particles on the brain are not all known yet and there could be more neurotoxic pollutants scientists are yet to discover. These risks are causes for concern — because each human only has one chance to develop a brain.
A ground-breaking study on the mental health burden of air pollution found that the more air pollution people were exposed to as children, the more likely they were to experience mental illness when they turned 18, the age when symptoms often appear.
Rather than focus on a specific diagnosis as in most previous studies, researchers studied participants’ responses to detailed survey questions about many symptoms. This included dependence on alcohol, cannabis, and tobacco, antisocial behaviour, eating disorders, depression, anxiety, post-traumatic stress, delusions and hallucinations.
The study used data on two air pollutants linked to altered brain health in previous studies – microscopic pollutant particles generated during industrial processes and combustion of fossil fuels and wood and nitrogen oxides, as well as pollutants associated with fossil fuel burning from power plants, vehicle emissions and certain industrial sites. Nitrogen oxide exposure showed clear evidence of worsening mental health.
While this research does not prove that air pollution causes mental illness, it does indicate that exposure to air pollution may increase the severity and substantially increase the social and financial burden of mental illness on communities.