Associations between total mortality and personal exposure to outdoor-originated NO2 in 271 Chinese cities

Abstract

Epidemiological studies have reported significant associations of outdoor NO2 with daily mortality. These studies used ambient NO2 concentrations as a proxy of personal exposure of outdoor-originated NO2 (PEO NO2), which may lead to biased health effect estimates. This study was aiming to explore whether modified outdoor NO2 exposure can reduce this error. We performed a Monte Carlo simulation to estimate the outdoor-originated NO2 concentration in residential buildings in 271 Chinese cities from 2013 to 2015, and then PEO NO2 was obtained according to time-activity-location patterns of people. We adopted a typical time-series analysis to compare the mortality associations between PEO and outdoor NO2. The averaged concentrations of PEO and outdoor NO2 were 16.5 μg/m3 and 31.6 μg/m3, respectively. PEO NO2 showed a better model fitting and larger effect for its daily mortality association. A 10 μg/m3 increase in two-day moving average concentration of PEO and outdoor NO2 was associated with a 2.08% (1.70%, 2.45%) and 1.03% (0.83%, 1.22%) increase in total mortality, respectively. Our study revealed that personal exposure to NO2 modified from outdoor NO2 concentrations may better reflect the health effects of air pollutants, and such evidence might be useful for future policy making and air pollution regulations.