Asthma patients who live in areas with high levels of air pollution are more likely to have uncontrolled asthma than those who live in less polluted areas, US research shows.
Writing in the Journal of Epidemiology and Community Health, Ying-Ying Meng (University of California, Los Angeles) and team explain: “The San Joaquin Valley (SJV) in California ranks among the worst in the USA in terms of air quality, and its residents report some of the highest rates of asthma symptoms and asthma-related emergency department (ED) visits and hospitalizations in California.”
To investigate associations between air pollution levels and asthma morbidity in this region, the researchers used data from the 2001 California Health Interview Survey to identify 1502 SJV residents with the respiratory condition.
Each participant’s residential zip code was used to assess average exposure to concentrations of ozone and fine particulate matter of less than 10.0 µm (PM10) and 2.5 µm (PM2.5) in diameter over the previous year, as measured by government air monitoring stations.
Uncontrolled asthma was defined as daily or weekly asthma symptoms, and/or asthma-related ED visits or hospitalization in the previous year.
After accounting for factors such as age, gender, race/ethnicity, socioeconomic and insurance status, the researchers found that the risk for uncontrolled asthma increased with exposure to increasing levels of air pollution.
Specifically, the risk for experiencing daily or weekly asthma symptoms increased by 23% for each 10-ppb increase in average annual ozone exposure, by 29% for each 10-µg/m3 increase in average annual PM10 exposure, and by 82% for each 10-µg/m3 increase in average annual PM2.5 exposure.
The risk for asthma-related ED visits or hospitalizations also increased 49% for each 10-ppb annual increase in ozone exposure, and by 29% for each 10-µg/m3 annual increase in PM10 exposure.
Meng and team conclude: “Overall, these findings suggest that individuals with asthma living in areas of the SJV with high ozone and particulate pollution levels are more likely to have frequent asthma symptoms and asthma-related ED visits and hospitalizations.”