A review of more than a decade of health and environmental data has led to the discovery of certain air pollutants that exacerbates asthma. In the study, “Association of Annual Exposure to Air Pollution Mixture on Asthma Hospitalizations in the United States,” researchers determined that the combination of certain metals and sulfates dramatically worsened the condition. The study was published in the American Journal of Respiratory and Critical Care Medicine.
According to the study’s authors, the mixture significantly increased the risk of asthma-related hospitalizations in both children and adults across the United States. Researchers examined inpatient records from 2002 to 2016 across 11 U.S. states, focusing on individuals aged zero–18 and 19–64. Using advanced statistical modeling, they assessed the cumulative impact of 15 airborne particle components — such as organic compounds and metals — alongside nitrogen dioxide (NO₂) and ozone (O₃).
The results were striking. For every decile increase in exposure to the pollutant mixture, asthma hospitalizations increased by 10.6% in children and 8% in adults. The pollutants most strongly linked to these increases included nickel, vanadium, sulfate, nitrate, bromine and ammonium.
“We know that particulate matter 2.5 (PM2.5) increases the risk of asthma attacks and hospitalizations, but those particles are made of many compounds, and we haven’t known which are most harmful. Our study teases out which specific compounds in the PM2.5 mixture necessitate the strongest control efforts to improve asthma outcomes,” Joel Schwartz, PhD, told News Medical. Dr. Schwartz is a professor of environmental epidemiology at the Harvard T.H. Chan School of Public Health in Boston and a corresponding author in the study.
According to Dr. Schwartz, the study underscores the importance of considering the combined effects of multiple pollutants, rather than evaluating them in isolation. The authors also emphasized the need for more granular, daily-level data to better understand short-term exposure risks.
The findings add to growing evidence that air quality regulations must account for complex pollutant interactions to protect vulnerable populations, especially children.
