Abstract: Objective To explore the health benefits of continuous control of atmospheric PM_2.5 concentration. Methods The average daily concentration of atmospheric pollutants,meteorological factors and mortality data in Yibin City from 2015-2020 were collected. Generalized additive models（GAM） were used to analyze the relationship between PM_2.5 concentration and years of life lost（YLL）. The avoidable YLL was calculated assuming that the air quality meet the World Health Organization Air Quality Guidelines（WHO AQG） and China's National Ambient Air Quality Standard Level 2. Gender and age groups were used to identify susceptible populations. Results When the concentration of PM_2.5（lag0） increased by 10 μg/m³,the non-acidental death YLL of residents increased by 0.72（95%CI：0.68-0.76）years,male（lag01） and female（lag03） increased by 0.61（95%CI：0.55-0.67） and 0.91（95%CI：0.84-0.99）years,respectively. At the same time >65（lag02） years old and ≤65（lag0） years old increased by 1.12（95%CI：1.05-1.19） and 0.45（95%CI：0.39-0.50）years,respectively. The YLL that could be avoided when PM_2.5 concentration reached the WHO AQG standard and the national secondary standard was 929.23（95%CI：877.02-981.44） and 124.70（95%CI：117.69-131.71） years,respectively. Conclusions PM_2.5 pollution may increase non-acidental deaths YLL,especially in women and the elderly（> 65 years old）.When PM_2.5 concentrations reach lower concentration thresholds,higher health gains can be achieved.

Key words: Fine particulate matter, Years of life lost, Generalized additive models, Assessment of health benefits