Evaluation of life expectancy loss associated with submicron and fine particulate matter (PM1 and PM2.5) air pollution in Nanjing, China

Particulate matters with an aerodynamic diameter <= 1 mu m (PM1) significantly increased mortality risk, and the effect of PM1 was even greater than that of PM2.5 (aerodynamic diameter <= 2.5 mu m). But the quantitative impact of PM1 on life expectancy was unknown. We aim to examine the extent to which that people's life expectancy was shortened by PM1 and PM2.5. We obtained daily data on deaths, PM1 and PM2.5 records, and weather variables during 2016-2017 in Nanjing, China. Years of life lost (YLLs) were calculated by matching each decedent's age and sex to the Chinese life table. The fitted nonlinear dose-response associations of YLLs with PM1 and PM2.5 were estimated by utilizing a generalized additive model with a Gaussian link that controlled for confounding factors including meteorological variables, day of week, and long-term trend and seasonality. The effect estimates were presented as the YLLs when PM1 and PM2.5 concentrations fell in different ranges. Life expectancy losses attributable to PM1 and PM2.5 were calculated. Stratified analyses were also performed by age, sex, and death causes. Significant PM-YLL associations were observed, with greater increases in YLLs associated with PM1 (68.9 thousand). PM1 was estimated to reduce life expectancy, which was greater than PM2.5 (PM1: 1.67 years; PM2.5: 1.55 years). For PM1, greater years of loss in PM-related life expectancy were found in the female group, >= 65 years group, and cardiovascular disease group. Exposure to PM1 had a greater impact on life expectancy loss than did PM2.5. Constant efforts are urgently needed to control PM1 air pollution to improve people's longevity.