The Impact of Drought and Airborne Pollutants on Pediatric Asthma in Imperial County, California, United States

Background: The Imperial Valley region of Southeastern California has become one of the most productive agricultural regions in the state and has the highest rates of childhood asthma in California. The pediatric population is at a unique and increased risk of immediate and long-term negative health effects of asthma from air pollution. 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 irrigation runoff, though the water level has diminished with drought conditions. Lakebed exposure may cause increased airborne particulate matter (PM), exacerbating asthma. Ongoing environmental changes increasingly require public health nurses to understand how environmental factors impact the health of vulnerable populations.

Methods: A proposed methodology is demonstrated for public health nurses to better understand and apply data from the HYSPLIT meteorological model to estimate the effect of airborne particulate matter from a single source. 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.

Results: 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). This indicates the possibility of the Salton Sea’s influence on pediatric asthma. The large confidence interval is notable, suggesting additional variables or pollutant sources, which is consistent with the study area, where several factors may contribute to air quality. Drought severity was not a significant moderator in the relationship between exposure and admissions, possibly due to the slow-response impact of drought that could not be captured.

Conclusions: Within public health and nursing, there is a need for broadening of skills beyond healthcare. Climate change-related environmental events are expected to disproportionately affect those with health disparities. Public health professionals are ideally positioned to assess environmental risk factors to vulnerable communities on a population scale.