Ambient particulate matter burden of disease in the Kingdom of Saudi Arabia

Background: Air pollution is one of the top 10 global health risk factors and has been associated with premature mortality, cardiovascular, cerebrovascular, respiratory, and metabolic disease. Currently, there is a lack of health assessments on the public health impacts of air pollution in the Kingdom of Saudi Arabia. Aim: This study aims to assess the ambient particulate matter burden of disease in the Kingdom of Saudi Arabia. Methods: A comparative risk assessment (CRA) using the 2017 Global Burden of Disease was performed to estimate ambient particulate matter exposure, mortality, and lost years of a healthy life. Saudi Arabia populationweighted mean concentrations of particle mass with an aerodynamic diameter less than 2.5 mu m (PM2.5), at an approximate 11 km x 11 km resolution was estimated using satellite-based estimates, chemical transport models, and ground-level measurements. The CRA for PM2.5 was based on relative risks originated from epidemiological studies using integrated exposure-response functions for ischemic heart disease, cerebrovascular disease, chronic obstructive pulmonary disease, lung cancer, lower respiratory infections, and type 2 diabetes. Mortality, years of life lost (YLL), years lived with disability (YLD) and disability-adjusted life years (DALYs) attributable to PM2.5 were estimated at the national level for all ages and both sexes from 1990 to 2017. Results: In 2017, the annual exposure to ambient particulate matter in the population-weighted mean PM2.5 in Saudi Arabia was 87.9 mu g/m3 (95% UI 29.6-197.9). The PM2.5 population-weighted mean has increased by 24% since 1990. Annual deaths attributable to PM2.5 were estimated at 8536 (95% UI 6046-11,080), representing 9% of the total annual deaths in Saudi Arabia. In 2017, 315,200 (95% UI 231,608-401,926) DALYs were attributable to PM2.5. Males contributed to 67% (209,822 (95% UI 151,322-277,503)) of DALYs, and females contributed to 33% (105,378 (95% UI 76,014-135,269) of DALYs. Ischemic heart disease represented 44% of the PM2.5 attributable DALYs, followed by type 2 diabetes (20%), lower respiratory infections (13%), stroke (11%), COPD (10%), and tracheal, bronchus, and lung cancer (3%). In 2017, 240,966 (95% UI 168,833-319,178) years of life lost (YLL) and 74,234 (95% UI 50,229-100,410) years lived with disability (YLD) were attributed to PM2.5. Conclusion: Ambient particulate matter is the fifth health risk factor in Saudi Arabia, contributing 9% of total mortality. Over the past 27 years, estimated exposure levels of PM2.5 in Saudi Arabia have been above WHO's air quality guidelines. Although since 2011 mortality and DALY rates attributable to PM2.5 have decreased, air pollution concentrations continue to increase. National and local authorities in Saudi Arabia should consider policies to reduce industrial and traffic-related air pollution in combination with the strengthening of current investments and improvements in health care and prevention services.