The Effects of Air Pollutants on Mortality in the Elderly at Different Ages: A Case of the Prefecture with Most Serious Aging in China

The elderly population is the main group sensitive to air pollution; however, the risks of multiple air pollutants on the elderly at different ages are not very clear. For this study, daily concentrations of five major air pollutants (PM10, NO2, SO2, CO, and O3) and daily mortality information of 173,537 people who died between 2014 to 2017 in Nantong, a prefecture with the most serious aging rate in China in 2000, 2010, and 2020, were collected; the aging people were divided into 2–6 groups according to age. A generalized additive model with a thin-plate spline function was used to study the exposure–response relationship, the excess risk, and the lag period of various pollutants on each group of the elderly, and the synergistic effect between these pollutants and temperature was demonstrated. The results revealed that, after controlling confounding factors such as temperature, humidity, and wind speed, the lag period and relative risk of most pollutants increased with age, and the adverse effect of air pollutants on the elderly lasted for 2–3 days. Among the pollutants, NO2, SO2, CO, and O3 had a longer lag period compared with PM10. Linear and non-linear exposure–response relationships were observed between the pollutants and mortality. Women were at higher risk than men for the same pollutant concentrations. Synergistic effects were observed between the five pollutants and temperature. This study could contribute to the formulation of a strategy to mitigate the effects of air pollution on the elderly at different ages and play a positive role in reducing the negative impact of air pollution on aging societies.