Impact of drought and airborne pollutants on pediatric asthma emergency
department visits in Imperial County, California, USA
Abstract
The pediatric population is at a unique and increased risk of immediate
and long-term health effects of asthma from air pollution. The years
2012-16 marked the worst drought in California, USA, in over a century.
Imperial County’s landlocked Salton Sea is almost entirely dependent on
agricultural runoff, where the water level has receded with drought
conditions. Lakebed soil exposure may cause increased airborne
particulate matter (PM), exacerbating asthma. Emergency department
admissions and diagnosis codes for asthma were obtained for children
ages 2-18, alongside population data to create population-weighted ZIP
code buffers. Trajectory analysis, dispersion modeling, and
meteorological data were used to determine likely PM exposure days.
Drought severity data were used to establish a relationship between
drought, exposure, and admissions. Conditional Poisson regression was
used to determine the risk of Salton Sea dust exposure to asthma and
moderating effects of drought. There is a significant relationship
between exposure from the Salton Sea and admissions on exposure days
(ERR 18.70%, p=0.012, 95%CI=3.936-35.623). Moderation analysis for
drought indicated no significant effect from two indicators (ERR
1.005%, 95%CI =-0.0.084-1.111, p=0.714; ERR 104.44%,
95%CI=8.44-285.426, p=0.316), pointing to the possibility that
particulates from the Salton Sea influence pediatric asthma. The large
confidence interval is notable, suggesting the influence of additional
pollutant sources, which is consistent with the study area, where a
variety of factors may contribute to air quality. Drought severity was
not a significant moderator between exposure and admissions, possibly
due to the slow-response impact of drought that was not captured.