Studies show no safe air quality threshold exists for heart & lung health

Two large US studies published by The BMJ found that short and long term exposure to fine particulate matter (PM2.5) air pollution is linked to an increased risk of hospital admission for major heart and lung diseases. The research from Harvard T.H. Chan School of Medicine suggests no safe threshold exists for heart and lung health, leading to an increased risk for hospital admissions. The findings have prompted the World Health Organization (WHO) to update air quality guidelines to recommend lower PM2.5 levels.

The first study conducted by researchers linked average daily PM2.5 levels to residential zip codes for nearly 60 million US adults aged 65 and over from 2000 to 2016. The study found that exposure to PM2.5 was associated with increased risks of hospital admissions for seven major types of cardiovascular disease, and compared to WHO air quality guidelines, exposures between 9 and 10 microgram per cubic metre were associated with a 29 per cent increased risk of hospital admission for cardiovascular disease. The researchers concluded that reducing annual PM2.5 below 5 microgram per cubic metre could avoid 23 per cent in hospital admissions for cardiovascular disease.

According to the researchers, these cardiovascular effects persisted for at least three years after exposure to PM2.5, and susceptibility varied by age, education, access to healthcare services, and area deprivation level. The findings of the study suggest that no safe threshold exists for the chronic effect of PM2.5 on overall cardiovascular health, and that substantial benefits could be attained through adherence to the WHO air quality guideline.

In the second study, researchers used county-level daily PM2.5 concentrations and medical claims data to track hospital admissions and emergency department visits for natural causes, cardiovascular disease, and respiratory disease for 50 million US adults aged 18 and over from 2010 to 2016. The study found that short term exposure to PM2.5, even at concentrations below the new WHO air quality guideline limit, was statistically significantly associated with higher rates of hospital admissions for natural causes, cardiovascular disease and respiratory disease, as well as emergency department visits for respiratory disease.

Overall, these two studies provide important insights into the health risks associated with PM2.5 air pollution and highlight the urgent need for stricter air quality guidelines and measures to reduce exposure to fine particulate matter. The findings underscore the importance of prioritizing public health and implementing policies to improve air quality in order to mitigate the health risks associated with PM2.5 pollution.