Most weather forecast services also provide information about local air quality which is determined by the concentration of various pollutants and fine particles. But even if air quality is considered “good,” long-term exposure to pollutants poses a health risk.
Current US air quality standards
Air quality is determined by the concentration of fine particles and other pollutants in the air at a certain place and time. The concentration of fine particles less than 2.5 micrometers (PM2.5), ozone (O3), and nitrogen dioxide (NO2), among others, are three criteria for air quality monitoring. The more concentrated they are in the atmosphere, the more air quality deteriorates.
In the United States, the U.S. Environmental Protection Agency (EPA) is responsible for monitoring air quality and its various levels. This shows that air quality is good when concentrations of PM2.5, O3, and NO2 do not exceed 12 µg/m3, 54 ppb, and 53 ppb respectively. But scientists at Harvard’s T.H. Chan School of Public Health disagree. According to their study, long-term exposure to air considered healthy still increases the risk of death in the elderly.
Is what is currently considered good quality air unhealthy?
To find out for sure, Harvard scientists followed several million Americans who were members of Medicare health insurance between 2000 and 2016 – mostly white seniors over the age of 65. This was done using the zip codes of these members and a simulation that mimics air quality in the United States using satellite data, weather data, and annual air quality reports from around the US. People living in an area with good air quality were followed, while others were voluntarily excluded.
According to the Harvard scientists’ findings, all three pollutants increase the risk of death in the elderly. A 1 µg/m3 increase in PM2.5 or 1 ppb increase in ozone or NO2 increases this risk after one year of exposure by 0.073%, 0.081%, and 0.003%, respectively. These figures amount to 11,540 deaths from PM2.5, 1,176 from NO2, and 15,115 from ozone per year and per unit increase. Men are more sensitive to PM2.5 and ozone, and African-Americans to ozone and nitrogen dioxide.
Air quality standards in the U.S not good enough
In 2020, the EPA did not lower PM2.5 thresholds. The WHO recently set the recommended threshold at 10 µg/m3, which is lower than the 12 µg/m3 considered by the United States. In their conclusion, the Harvard scientists write that “our results provide evidence that the EPA administrator’s choice of the annual PM2.5 standard was unjustified.” In many countries, the air quality standards are those set by the WHO.
Limiting our emissions of gas pollutants and fine particles is a real public health issue. Outdoor air pollution has been classified as a class 1 carcinogen by the IARC (International Agency for Research on Cancer) since 2013. It increases the risk of lung cancer but also bladder cancer. It is the most common carcinogen in the world.
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