Air Pollution Increases Healthcare Utilization Below Safe Thresholds in Individuals With Asthma.

PURPOSE

Safety thresholds for air quality levels have been proposed to protect people from the harmful effects of air pollutants. However, the impacts of air pollutants on asthma, particularly at levels below these safe thresholds, remain unclear.

METHODS

We analyzed the associations between air pollutants (particulate matter of 10 μm or less in diameter [PM₁₀], particulate matter of 2.5 μm or less in diameter, sulfur dioxide [SO₂], carbon monoxide, ozone [O₃], and nitrogen dioxide) and healthcare utilization in 23,498 individuals with asthma in Seoul during the 2015-2017 season. The relative risk for healthcare utilization was assessed based on quantitative comparison (upper quartile vs. lower quartile) and non-linear concentration-response curves. Safety thresholds for air quality levels were determined according to the World Health Organization and Korean standards.

RESULTS

In quantitative analysis, healthcare utilization risk decreased for PM₁₀ and SO₂ but increased for O₃ on lag day 0, with no significant associations observed for other air pollutants. Non-linear analyses revealed significant concentration-response associations for all air pollutants, indicating increased risks of healthcare utilization on lag day 0. Notably, these increased risks occurred below proposed safety thresholds, with a steeper rise observed for asthma-related healthcare utilization within these ranges.

CONCLUSIONS

Exposure to 6 air pollutants was associated with an increased risk of healthcare utilization among individuals with asthma, with no safe exposure levels identified. The impact was more pronounced below current safety thresholds.