Sensitivity of estimated NO2-attributable pediatric asthma incidence to grid resolution and urbanicity

Nitrogen dioxide (NO2) is a major urban air pollutant and is associated with new onset asthma among children worldwide. Since NO2 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 NO2-attributable pediatric asthma cases. Here, we investigate the effect of spatial resolution of exposure and population data on estimated NO2 attributable pediatric asthma incidence. We use epidemiologically-derived health impact functions to estimate NO2-attribtuable asthma incidence for the U.S. and India, two countries with different degrees of urbanicity. As inputs to the health impact function, we use population and NO2 concentration estimates at 100m resolution and aggregated to coarser spatial resolutions: 500m, 1km, 10km, and 100km. Estimated NO2-attributable pediatric asthma burdens differ by <1% for resolutions of 100m up to 1km for both countries. However, performing the analysis at 10km and 100km results in 5% and 17% fewer new asthma cases among children in India and 6% and 32% fewer in the U.S., respectively. We perform a similar analysis for the 500 most populated cities at 1km and 10km resolution, finding that the coarser resolution leads to lower estimated NO2-attributable asthma incidence in nearly all cities, especially for cities with smaller land areas. We conclude that 1km spatial resolution balances accuracy and computational efficiency in estimating NO2-attributable asthma burdens at national and urban levels, and that coarser resolutions may result in underestimates.