Particulate Matter Exposure Linked With Incident Asthma

Long-term exposure to intermediate particulate matter is associated with incident asthma in adults aged 45 years and older, according to a recent study.

Shuting Li of the Capital Medical University in Beijing, China, and the Beijing Municipal Key Laboratory of Clinical Epidemiology, and colleagues conducted the study due to “insufficient evidence about the long-term effects of intermediate particulate matter on asthma development in adults aged 45 years and above.”

The researchers conducted the cohort study using the China Health and Retirement Longitudinal Study database to evaluate the long-term effects of intermediate particulate matter on the incidence of self-reported asthma in 6400 adults aged 45 years and older in China from 2011 to 2018. They estimated the particulate matter concentrations using a high-resolution, satellite-based spatiotemporal model.

After 7 years of follow-up, 1.61% of the participants developed asthma, with each 10 μg/m3 increment in the 1-year moving average concentration of intermediate particulate matter corresponding to a 1.82-fold increased risk for incident asthma.

Each 10 μg/m3 increment in the 2-year moving average concentration corresponded to a 1.95-fold higher risk for incident asthma, while each 10 μg/m3 increment in the 3-year and 4-year moving averages corresponded to 1.95-fold and 1.88-fold increased risks of incident asthma, respectively.

“A significant multiplicative interaction was observed between socioeconomic level and long-term exposure to [intermediate particulate matter],” the researchers wrote. “Stratified analysis showed that smokers and those with lower socioeconomic levels were at higher risk of incident asthma related to [intermediate particulate matter].”

They also found an increasing trend in asthma incidence with increasing intermediate particulate matter.

“Long-term exposure to [intermediate particulate matter] was positively associated with incident asthma in middle-aged and elderly individuals,” the study’s authors concluded. “Participants with a history of smoking and lower socioeconomic levels had a higher risk. More studies are warranted warrant to establish an accurate reference value of [intermediate particulate matter] to mitigate the growing asthma burden.”

Li S, Wei J, Hu Y, et al. Long-term effect of intermediate particulate matter (PM1-2.5) on incident asthma among middle-aged and elderly adults: a national population-based longitudinal study. Sci Total Environ. 2022. doi:10.1016/j.scitotenv.2022.160204