Years of life lost attributable to air pollution, a health risk-based air quality index approach in Ningbo, China

Air pollution remains a significant threat to human health and economic development. Most previous studies have examined the health effects of individual pollutants, which often overlook the combined impacts of multiple pollutants. The traditional composite indicator air quality index (AQI) only focuses on the major pollutants, whereas the health risk-based air quality index (HAQI) could offer a more comprehensive evaluation of the health effects of various pollutants on populations. Currently, research on HAQI to evaluate the influence of multiple air pollutants on life expectancy losses is limited. In this study, we employed HAQIto estimate years of life lost (YLL) caused by exposure to air pollution for total deaths and sub-groups by sex, age, and cause-specific disease in Ningbo from 2014 to 2018. Results reveal that significant improvement in air quality during the study period. Based on the AQI-classified air quality risk category, the HAQI estimated a more severe level, which suggests that the commonly used AQI significantly underestimates the hazards of multiple air pollutants. The YLL attributable to exposure above threshold concentrations of the Chinese Ambient Air Quality Standards (CAAQS) 24-hour Grade II standards was 1.375 years (95% CI, 1.044-1.707) per death based on the HAQI, while the YLL estimated using AQI was 1.047 years (95% CI, 0.809-1.286) per death. Females and elderly people over 65 years were vulnerable subgroups, with YLL of 1.232 and 1.480 years per death, respectively. Among deaths of cause-specific disease, the YLL attributed to polluted air was highest for patients with respiratory diseases (0.866 years, 95% CI: 0.668-1.064), followed by patients with circulatory diseases (0.490 years) and endocrine diseases (0.478 years), respectively. Improving the standards of air quality could promote the management of air quality and reduce the disease burden and economic losses caused by polluted air to populations, especially for vulnerable populations. Our study provides a basis for the formulation of policies and upgrade of air quality standards.