Two American studies published in the British Medical Journal have found that both short and long-term exposure to air pollution from PM2.5 fine particles is linked to a greater risk of hospitalization for serious heart and respiratory diseases. This research suggests that there is no safe threshold of pollutants for heart and lung health.
In the first study, researchers linked average daily PM2.5 levels to the zip codes of residence of nearly 60 million US adults over 65 from 2000 to 2016. Through Medicare data, they tracked hospitalizations over an average of 8 years and found that average exposure to PM2.5 over 3 years was associated with an increase in the probability of a first hospitalization for 7 types of cardiovascular pathologies. This means that reducing annual PM2.5 levels below 5 µg/m3 could potentially avoid 23% of hospitalizations for cardiovascular diseases.
In 2021, the World Health Organization updated air quality guidelines, recommending that annual average levels of PM2.5 particulate matter should not exceed 5 micrograms per cubic meter (µg/m3). However, according to the study, adhering to these guidelines could still result in substantial benefits, but there is no safe threshold for the chronic effect of PM2.5 on general cardiovascular health.
The second study looked at daily county-level PM2.5 concentrations and medical claims data to track hospital admissions and emergency room visits for natural causes, cardiovascular disease, and respiratory disease among 50 million American adults over 18 since 2000 to 2016. The investigation found that short-term exposure to PM2.5, even at concentrations lower than those set by the WHO, is statistically significantly associated with higher hospitalization rates for natural causes, cardiovascular and respiratory diseases, as well as emergency room visits due to natural causes and respiratory disease.
The researchers concluded that these new data represent a valuable reference for future national standards on air pollution. This research highlights the urgent need to address air pollution to protect public health, as there is no safe level when it comes to the impact of PM2.5 on heart and lung health.