Two new studies suggest there is no safe air quality threshold for heart and lung health
Short-term and long-term exposure to fine particulate matter (PM2.5) air pollution is associated with an increased risk of hospitalization for major heart and lung diseases, two studies published today by the BMJ show. This was revealed in a large-scale study in the United States.
Taken together, these results suggest that there is no safe threshold for heart and lung health.
According to the Global Burden of Disease Study, exposure to PM2.5 accounts for an estimated 7.6% of global total mortality and 4.2% of global disability-adjusted life years (a measure of years lived in good health).
Given this extensive evidence, the World Health Organization (WHO) updated its air quality guidelines in 2021 to ensure that annual average PM2.5 levels do not exceed 5 μg/m3 and to ensure that 24-hour average PM2.5 levels do not exceed 15 μg. It was recommended not to exceed /m3. μg/m3 occurs over 3-4 days each year.
In the first study, researchers compared average daily PM2.5 levels and residential ZIP code for nearly 60 million U.S. adults aged 65 and older (84% white, 55% female) from 2000 to 2016. associated with. The hospitals were then tracked using Medicare insurance data. Enrollment spans an average of 8 years.
After considering a range of economic, health, and social factors, the average PM2.5 exposure over a three-year period was Aortic aneurysm.
Compared to exposures below 5 μg/m3 (WHO air quality guidelines for annual PM2.5), exposures between 9 and 10 μg/m3 were associated with a US national average of 9.7 μg/m3 during the study period. . 29% increased risk of hospitalization for cardiovascular disease.
On an absolute scale, the risk of hospitalization for cardiovascular disease increased from 2.59% for exposures below 5 μg/m3 to 3.35% for exposures between 9 and 10 μg/m3. “This means that if we can keep PM2.5 below 5 μg/m3 per year, we could avoid 23% of cardiovascular hospitalizations,” the researchers said*.
These cardiovascular effects persisted for at least 3 years after exposure to PM2.5, and susceptibility varied by age, education, access to health services, and local poverty level.
The researchers concluded that their findings indicate that there is no safe threshold for the chronic effects of PM2.5 on overall cardiovascular health and that there are substantial benefits from adhering to WHO air quality guidelines. This suggests that there is a possibility that
“On February 7, 2024, the U.S. Environmental Protection Agency (EPA) updated the National Air Quality Standard for annual PM2.5 levels, setting a stricter limit of 9 μg/m3 or less, the first since 2012. This is the first update, but this is the first update since 2012. “It is still significantly higher than the 5 μg/m3 set by the WHO. Clearly, the newly published national standard is not sufficient to protect public health. There was no,” they added*.
In the second study, researchers used county-level daily PM2.5 concentrations and medical claims data to determine whether natural causes, cardiovascular Hospitalizations and emergency department visits due to illness, respiratory illness were tracked. .
Over 10 million hospitalizations and 24 million emergency department visits were recorded during the study period.
Researchers found that short-term exposure to PM2.5, even when its concentrations are below the limits in the WHO’s new air quality guidelines, is associated with increased rates of hospitalization due to natural causes, cardiovascular disease, respiratory disease, and We found a statistically significant association with increased rates of emergency room visits. Respiratory diseases.
For example, on days when daily PM2.5 levels are below the new limit of 15 μg/m3 in the WHO air quality guidelines, a 10 μg/m3 increase in PM2.5 would result in 1.87 deaths per million 18-year-old adults. Additional hospitalizations occurred. More than per day.
The researchers say their findings make an important contribution to the debate about revising air quality limits, guidelines and standards.
Both research teams acknowledged some limitations, including possible misclassification of exposure, and noted that other unmeasured factors may have influenced the results. Additionally, the findings may not apply to individuals without health insurance, children and adolescents, or those living outside the United States.
But taken together, these new results provide a valuable reference for future national air pollution standards.
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