Sector-, Season-, and Country-Specific NO2-Associated Health Benefits from NO x Emission Reductions.

Long-term exposure to NO₂ is associated with elevated risks for pediatric asthma and premature death. Despite national policies targeting NO₂'s main source, NO _x emissions, its global health burden remains high. Here, we use the air quality model GEOS-Chem adjoint with TROPOspheric Monitoring Instrument (TROPOMI)-based satellite downscaling to estimate that long-term NO₂ exposure is responsible for 2.07 (95% CI 0.91-2.70) million pediatric asthma cases and 1.98 (95% CI 0.52-2.86) million deaths globally in 2019. We attribute these to anthropogenic NO _x emissions by sector, country, and season using the adjoint model and provide a recommendation for the most impactful sector and season for NO _x emission controls in each G20 country. Discrepancies exist between the health benefits incurred by emission reductions and the emission sector distributions, particularly in countries with emitters adjoining population centers. For example, we find that, if Russian anthropogenic NO _x emissions were reduced uniformly by 10% across all sectors, the energy sector, 31% of annual NO _x emissions, would account for 47% of pediatric asthma and 49% of premature death health benefits. The season in which these emission reductions occur also affects the magnitude of the health benefit, as seen by the fact that Russian wintertime NO _x emission reductions alone are responsible for approximately one-third of the annual health benefits for each health outcome. We present the unique results for each of the G20 members to showcase how a country's NO _x emission reductions can be most impactful in reducing the global NO₂-associated health burden.