Longitudinal Impacts of PM_2.5 Constituents on Adult Mortality in China

Abstract

Limited evidence exists for long-term effects of PM 2.5 constituents on mortality. Hence, we aimed to assess associations between all-cause mortality and long-term exposure to PM 2.5 constituents in China. We designed a nationwide cohort study of 30524 adults from 162 prefectural areas across mainland China with follow-ups through years 2010−2017. Cox proportional hazards models with time-varying exposures were employed to quantify associations between all-cause mortality and long-term exposure to PM 2.5 and constituents. A total of 1210 deaths occurred during 172297.7 person-years. A multiadjusted Cox model estimated an hazard ratio (HR) of 1.125 (95% confidence interval: 1.058−1.197) for all-cause mortality, associated with an interquartile range (IQR = 26.7 μg/m 3 ) rise in exposure to PM 2.5 . Comparable or stronger associations were found among PM 2.5 constituents with the mortality risk increased by 11.3−14.1% per IQR increase in exposure concentrations. After adjustment for the collinearity between total PM 2.5 and constituents, effect estimates for nitrate, ammonium, and sulfate remained significant and became larger. Urban residents, alcohol drinkers, smokers, and men were more susceptible to chronic impacts from ambient PM 2.5 constituents. This cohort study added the novel longitudinal evidence for elevated mortality linked with long-term exposure to PM 2.5 constituents among Chinese adults.

National Cohort Study of Long-Term Exposure to PM2.5 Components and Mortality in Medicare American Older Adults

“… 30 In addition, animal studies have reported that exposure to NO 3 – may result in lung inflammatory cell infiltration, alveoli collapse, and thickening of the small airway wall. 31 We also discovered a strong link between NH 4 + and mortality, and the strength of the observed association was consistent with previous studies 23 , 32 that the effect of NH 4 + ranked top among the contributing factors. However, it is unclear whether the observed associations are due to their intrinsic toxicity or because they are associated with other combustion-emitted culprit pollutants.…”

“…We observed linear relationships with BC (Exposure II), SO 4 2– , and NH 4 + , with no indication of a threshold for either outcome, and the previously published studies in Southeastern U.S. and China also reported similar linear association for BC (Exposure II), NO 3 – , and SO 4 2– . 20 , 23 We observed nonlinear “bell-shaped” C – R relationships between exposure to BC (Exposure I), OM, and DUST and mortality, indicating that the relationships are increasing steeply at low to moderate exposure levels and leveled off at high exposure levels. There have been many theories proposed to explain the reasons causing a nonlinear C – R relationship, including preferential avoidance based on symptoms, decreased inhalation, and errors in estimating pollution exposure levels at elevated concentrations.…”

“…. 20,23 We observed nonlinear "bell-shaped" C−R relationships between exposure to BC (Exposure I), OM, and DUST and mortality, indicating that the relationships are increasing steeply at low to moderate exposure levels and leveled off at high exposure levels. There have been many theories proposed to explain the reasons ).…”

“…A recently published panel study demonstrated that the hypothalamic–pituitary–adrenal axis can be activated by exposure to SO 4 2– , NH 4 + , and NO 3 – , which may affect the cardiovascular system. 21 Previous large-scale epidemiology studies also suggested that secondary inorganic aerosols were connected to all-cause, cardiovascular disease, and cardiopulmonary mortality in Denmark, 22 China, 23 and U.S. 24 Sulfur dioxide (SO 4 2– precursor) has natural sources (e.g., oceans and volcanic emissions) and anthropogenic emissions primarily from fossil fuel combustion. SO 4 2– can alter bronchial mucociliary transport in humans, 25 change the alveolar macrophage function, 26 and influence aortic contraction.…”

Exposure to Fine Particulate Matter Constituents and Human Semen Quality Decline: A Multicenter Study

“…Prior research has indicated that PM 2.5 can pose risks to a variety of health outcomes such as mortality, lung cancer, and respiratory and cardiovascular diseases. Additionally, in recent years, its detrimental impact on reproductive health has garnered widespread attention. − …”