Exploring Health Effects under Specific Causes of Mortality Based on 90 Definitions of PM_2.5 and Cold Spell Combined Exposure in Shanghai, China

Abstract

In this study, a total of 90 definitions were set up based on six air pollution definitions, five cold spell definitions, and three combined exposure scenarios. The relative risks (RRs) on all-cause, circulatory, and respiratory mortality were explored by a model combining a distributed linear lag model with quasi-Poisson regression. The definition in which daily PM2.5 increases more than 75 μg/m3 for at least 2 days and the average temperature falls below the 10th percentile for at least 2 days produced the best model fit performance in all-cause mortality. The high peaks of the health effect were generally observed around the lag days 6–9. The cumulative relative risks (CRRs) were more significant in the simultaneous-exposure scenario and higher in respiratory mortality, where the highest CRR (12.15, 3.69–40.03) was observed in definition P1T5, in which daily PM2.5 increases more than 75 μg/m3, and the average temperature falls below the 2.5th percentile for at least two days. For relative risk due to interaction (RERI), we found positive additive interactions (RERI > 0) between PM2.5 pollution and cold spell, especially in respiratory mortality. Clarifying the definition of combined events can help policymakers to capture health risks and construct more effective risk warning systems.

Effects of the interaction between cold spells and fine particulate matter on mortality risk in Xining: a case-crossover study at high altitude

“…This study, for the first time, uses the REOI, AP, and S to comprehensively assess the health impacts of cold spells and PM 2.5 interactions of varying intensities and durations, providing a new perspective for research in this field. This study confirms the synergistic effect of combined exposure to cold spells and PM 2.5 on specific causes of death, especially in increasing the risk of respiratory deaths, aligning with previous research results from the Shanghai region ( 69 ). As the intensity and duration of cold spells increased, the independent impact of the cold spells and their interaction with PM 2.5 on health appeared to diminish.…”

The interactive effects of extreme temperatures and PM2.5 pollution on mortalities in Jiangsu Province, China

“…means cross-basis function obtained by applying the DLNM to COMB t , with a strata function and a natural cubic spline function (NS) with 4 dfs for exposure- and lag-response dimensions. To account for the detected chronicity of cold effects and acuteness of heat events, we set the maximum lag in cold seasons at 27 days and for hot seasons at 7 days 17 , 40 , 41 . is the daily death number from total, non-accidental, or cause-specific disease for region c on day t .…”

“…Emerging evidence of the interactions between extreme temperatures and air pollutants was also observed. Various studies conducted in China and the United States have explored the interactive effect between extreme temperatures and the main air pollutants (such as PM 2.5 , PM 10 , SO 2 , and NO 2 ) on preterm birth, total and cause-specific mortalities, and detected positive interactions of cold spells and heat waves with air pollutants on respiratory and circulatory disease mortalities 17 – 24 . Studies that focused on the interactions of the Air Quality Index and extreme temperatures in China, however, indicated conflicting interactive effects on respiratory disease hospitalization and mortality 25 , 26 .…”

Interaction between Extreme Temperature Events and Fine Particulate Matter on Cardiometabolic Multimorbidity: Evidence from Four National Cohort Studies

“…Several epidemiological studies have reported similar interaction effects on mortality or hospital visits. 24,25,57 However, the possible synergistic effects of PM 2.5 pollution and ETEs exposure on CMM are not assessed yet. Currently, we evaluated the additive interactions of ETEs and PM 2.5 Abbreviations: PM 2.5 , fine particulate matter; CMM, cardiometabolic multimorbidity; RERI, relative excess risk due to interaction; AP, attributable proportion due to interaction; S, synergy index; HW11, heat wave frequency for the definition of daily average temperature equal to or higher than 97.5th percentile for at least 3 consecutive days; CS10, cold spell frequency for the definition of daily average temperature lower than 2.5th percentile with at least 2 consecutive days; NO 58 Another finding from the CLHLS cohort also reported such a synergistic adverse effect of heatwave and PM 2.5 pollution on hypertension incidence.…”

“… 23 Recent evidence indicated that both heatwave and cold spell interact synergistically with PM 2.5 pollution, resulting in an increased risk of circulatory mortality. 24 , 25 However, whether ETEs, PM 2.5 , and its constituents work together synergistically to heighten the risk of CMM remains unknown.…”