Interactive Effects Between Temperature and PM_2.5 on Mortality: A Study of Varying Coefficient Distributed Lag Model — Guangzhou, Guangdong Province, China, 2013–2020

Abstract

Introduction: There is a large body of epidemiological evidence showing significantly increased mortality risks from air pollution and temperature. However, findings on the modification of the association between air pollution and mortality by temperature are mixed.Methods: We used a varying coefficient distributed lag model to assess the complex interplay between air temperature and PM 2.5 on daily mortality in Guangzhou City from 2013 to 2020, with the aim of establishing the PM 2.5 -mortality association at different temperatures and exploring synergetic mortality risks from PM 2.5 and temperature on vulnerable populations.Results: We observed near-linear concentrationresponse associations between PM 2.5 and mortality across different temperature levels. Each 10 μg/m³ increase of PM 2.5 in low, medium, and high temperature strata was associated with increments of 0.73% [95% confidence interval (CI): 0.38%, 1.09%], 0.12% (95% CI: −0.27%, 0.52%), and 0.46% (95% CI: 0.11%, 0.81%) in non-accidental mortality, with a statistically significant difference between low and medium temperatures (P=0.02). There were significant modification effects of PM 2.5 by low temperature for cardiovascular mortality and among individuals 75 years or older.Conclusions: Low temperatures may exacerbate physiological responses to short-term PM 2.5 exposure in Guangzhou, China. METHODSThe study period was 2013-2020. We obtained daily mortality data in Guangzhou from Guangzhou Center for Disease Control and Prevention. Causes of death were classified according to International

Exploring Health Effects under Specific Causes of Mortality Based on 90 Definitions of PM2.5 and Cold Spell Combined Exposure in Shanghai, China

“…Similarly, interactive research showed that the health effect of PM 2.5 was significantly higher at low temperatures. 40,41 In these studies, air pollution and low-temperature events occurred simultaneously, which supported the result in scenario A. In addition, it has been reported that the cold spell could be attributed to specific causes of mortality, and its health effect could continue for 3−27 days and climb to the highest on the 5−15th lag day.…”

“…29,43,44 Joint effect research showed the highest effect of PM 2.5 on mortality in lowtemperature strata compared with high-and medium-temperature strata. 40 In this study, all-cause, circulatory, and respiratory mortality were significantly influenced by combined events. The joint effects between in air pollution and cold spell for all-cause mortality, nonaccidental mortality, cardiovascular mortality, respiratory mortality, or mental disease were found in previous studies.…”

“…The joint effects between in air pollution and cold spell for all-cause mortality, nonaccidental mortality, cardiovascular mortality, respiratory mortality, or mental disease were found in previous studies. ,,, When exposed to cold temperature or air pollution, the airway epithelium is irritated, which causes the body to respond with coughing, bronchoconstriction, and mucosal secretion. , Cold stress and PM 2.5 experiments in adulthood of mice showed that coexposure may promote the deterioration of asthma symptoms by increasing inflammatory cytokines, ROS formation, Th2/Th1 imbalance, and suppressing the differentiation of Th17 toward Treg cells. , Further deaths from respiratory disease will occur in sensitive individuals (e.g., elderly people, etc. ). , Although no joint effect research showed an association between combined events and circulatory mortality, the circulatory system remains one of the leading causes of death from cold spell events or air pollution events.…”

“…47,48 Further deaths from respiratory disease will occur in sensitive individuals (e.g., elderly people, etc.). 6,40 Although no joint effect research showed an association between combined events and circulatory mortality, the circulatory system remains one of the leading causes of death from cold spell events or air pollution events.…”

Association between ambient cold exposure and mortality risk in Shandong Province, China: Modification effect of particulate matter size

“…Similar findings were reported in Europe, where cold temperature was observed to have a greater impact on total mortality and cardiovascular mortality on days with high PMs levels ( 13 ). Another Chinese study also showed that the death risk of PM 2.5 at low temperature was higher than that at medium temperature ( 27 ). Cold temperatures can lead to vasoconstriction and the release of inflammatory markers in the blood, which may increase blood pressure and vascular resistance, and finally trigger cardiovascular events ( 28 ).…”