Environmental Research Letters (Jan 2020)
Sensitivity of estimated NO2-attributable pediatric asthma incidence to grid resolution and urbanicity
Abstract
Nitrogen dioxide (NO _2 ) is a major urban air pollutant and is associated with new onset asthma among children worldwide. Since NO _2 concentrations are spatially heterogeneous and correlated with population, the spatial resolution of concentration estimates and disease burden calculations could strongly influence the magnitude and spatial distribution of estimated NO _2 -attributable pediatric asthma (PA) cases. Here, we investigate the effect of spatial resolution of exposure and population data on estimated NO _2 attributable PA incidence. We use epidemiologically derived health impact functions to estimate NO _2 -attributable asthma incidence for the U.S. and India, two countries with different degrees of urbanicity, using population and NO _2 concentration estimates at 100 m resolution and aggregated to coarser spatial resolutions: 500 m, 1 km, 10 km, and 100 km. Estimated NO _2 -attributable PA burdens differ by <1% for resolutions of 100 m up to 1 km for both countries. However, performing the analysis at 10 km and 100 km results in 5% and 17% fewer new asthma cases among children in India and 6% and 32% fewer in the U.S., respectively. We performed a similar analysis for the 13 000 urban areas and present the results for the 500 most populated cities at 1 km and 10 km resolution, finding that the coarser resolution leads to lower estimated NO _2 -attributable asthma incidence in nearly all cities, especially for cities with smaller land areas. We conclude that 1 km spatial resolution is a good balance between accuracy and computational efficiency in estimating NO _2 -attributable asthma burdens at national and urban levels, and that coarser resolutions may result in underestimates.
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