A study of 60 million Americans 65 years old and older (the entire Medicare population) found that long-term exposure to airborne fine particulate matter (PM2.5) and ozone at concentrations below current national standards increases the risk of premature death ("all cause mortality") even when the levels are below current national standards. This effect was most pronounced among racial minorities and people with low income. The national standards are called National Ambient Air Quality Standards (NAAQS), and they are established by the U.S. Environmental Protection Agency (EPA).
Note that PM2.5 refers to fine particles in the air smaller than 2.5 micrometers - these are truly small particles. It is thought that these tiny particles contribute to the development of potentially fatal diseases various ways - by causing chronic inflammation, and also because they slip past the body's defenses and can be absorbed deep into the lungs and bloodstream. They are not sneezed or coughed out the way larger natural particles (like airborne soil and sand) are removed from the body's airways.
These study results are a strong argument in support of the view that our air needs to be protected and standards need to be strengthened - not loosened. Earlier posts on this topic have found links between air pollution (especially fine particulate matter smaller than 2.5 micrometers) and cognitive decline and dementia in older women, strokes, high blood pressure, an increase in death (especially cardiovascular disease), etc. From Medical Xpress:
A new study of 60 million Americans—about 97% of people age 65 and older in the United States—shows that long-term exposure to airborne fine particulate matter (PM2.5) and ozone increases the risk of premature death, even when that exposure is at levels below the National Ambient Air Quality Standards (NAAQS) currently established by the U.S. Environmental Protection Agency.
The Harvard T.H. Chan School of Public Health researchers found that men, blacks, and low-income populations had higher risk estimates from PM2.5 exposure compared with the national average, with blacks having mortality risks three times higher than the national average. The results showed that if the level of PM2.5 could be lowered by just 1 microgram per cubic meter (ug/m3) nationwide, about 12,000 lives could be saved every year. Similarly, if the level of ozone could be lowered by just 1 part per billion (ppb) nationwide, about 1,900 lives would be saved each year.
"This is a study of unprecedented statistical power because of the massive size of the study population. These findings suggest that lowering the NAAQS for fine particulate matter will produce important public health benefits, especially among self-identified racial minorities and people with low incomes," said Francesca Dominici, principal investigator of this study and professor of biostatistics at Harvard Chan School and co-director of the Harvard Data Science Initiative.
The researchers examined Medicare claims records of 60 million Americans 65+ over a seven-year period, representing 460 million person-years of follow-up. They also estimated air pollution levels at each 1 kilometer grid for the entire U.S. upon which the claims data could be overlaid and interpreted. .... By relying on this well-validated prediction model, the team was able to include subjects who live in unmonitored and less-populated areas so that the effects of air pollution on all 60 million people could be analyzed regardless of whether they lived in urban, suburban, or rural areas. "This study shows that although we think air quality in the United States is good enough to protect our citizens, in fact we need to lower pollution levels even further," said Schwartz. [Original study in New England Journal of Medicine.]