Three studies found damage to the heart and brain from fine particulate pollutants.

In the first study, a team from the Harvard School of Public Health documented an association between long-term exposure to PM2.5 and an increased risk of hospitalization for serious heart and lung disease. Analyzing data from nearly 60 million American adults over 16 years, they found a significant correlation between PM2.5 levels and hospitalization for a variety of cardiovascular diseases, from coronary heart disease to aortic aneurysm. The results show that even small reductions in pollution can have a significant impact on public health.

To conduct the study, a team from the Harvard School of Public Health linked average daily levels of PM2.5 particles between 2000 and 2016 to the zip codes of nearly 60 million American adults (84% of them white and 55% women). They then used Medicare insurance data to track hospitalization rates over an eight-year average. Taking into account a range of economic, health and social factors, average exposure to PM2.5 over three years was associated with an increased risk of first hospitalization for seven major types of cardiovascular disease: coronary heart disease, cerebrovascular disease, heart failure, cardiomyopathy, arrhythmia, diseases heart valves and aneurysms of the thoracic and abdominal aorta. The findings of this work suggest that if annual PM2.5 levels could be reduced below 5 µg/m3, we could avoid 23% of hospitalizations due to cardiovascular disease.

The researchers say their findings show that there is no safe threshold for chronic PM2.5 exposure to overall cardiovascular health and that significant benefits can be achieved if WHO air quality guidelines are followed.

The regulatory framework is also undergoing changes. On February 7, 2024, the US Environmental Protection Agency (EPA) updated the national air quality standard for PM2.5, although it still significantly exceeds WHO recommendations. The move underscores the urgent need for stronger action to address this public health problem.

Another study by researchers at Boston University School of Public Health found that even short-term exposure to relatively low levels of PM2.5 is associated with significant increases in hospitalizations and emergency department visits for cardiovascular and respiratory diseases. These results highlight the need for ongoing surveillance and preventive measures to protect the health of exposed communities.

Additionally, a study published in the journal Neurology by researchers at Emory University in Atlanta shows a link between air pollution and Alzheimer’s disease. By examining brain tissue from deceased donors, they found a link between PM2.5 exposure and the accumulation of amyloid plaques in the brain, a key marker of this neurodegenerative disease. These findings suggest that air pollution may be an important environmental factor in the development of the disease, even in the absence of genetic predisposition.

For the study, researchers examined brain tissue from 224 people who agreed to donate their brains after death to advance dementia research. People died at an average age of 76 years. The researchers examined exposure to traffic-related air pollution based on the home address of people in the Atlanta area at the time of death. They found that people who were exposed to more air pollution one and three years before death were more likely to have higher levels of amyloid plaques in their brains.