Effects Of Humidity On The Burden Of Cardiovascular Disease Related To Extreme Weather

Background: Environmental change has been an important factor influencing the development of cardiovascular disease.Recent studies have shown a strong association between heat wave and cold spell with cardiovascular disease(CVD)morbidity or mortality,but controversy remains due to the different results of heat wave or cold spell definitions.Among these,it is less well reported about changes in the risk of cardiovascular disease mortality due to heat wave and cold spell in areas of high humidity,and it is unclear whether humidity alters the relationship between heat waves or cold spell and cardiovascular disease mortality.Objectives: 1.to understand the weather characteristics of extreme temperatures and the burden of cardiovascular disease in Hunan Province.2.to explore the effects of heat wave and humidity on cardiovascular disease mortality.3.to explore the effects of cold spell and humidity on cardiovascular disease mortality.Methods: 1.Daily CVD mortality data from 2017-2020 in Hunan Province were collected.The ERA5-Land reanalysis dataset from the European Centre for Medium-Range Weather Forecasting was used to obtain daily average temperature,daily air quality index,and daily relative humidity data for Hunan Province,and air quality index data for each city in Hunan Province from the China Air Quality Monitoring Online Monitoring and Analysis Platform.2.Using different temperature threshold and duration,we defined 12 types of heat waves and cold spells.A over-dispersed generalized additive models with distributed lag models to estimate was used to assess the association between heat wave or cold spell or relative humidity with CVD hospitalization or mortality in 14 cities in Hunan Province.The effect values of different cities were pooled using meta-analysis.Minimized generalized cross-validation(GCV)was used to determine the best-fitting heat wave or cold spell definitions.3.A distributed lag nonlinear model was used to assess the risk of cardiovascular disease mortality associated with optimal heat wave or cold spell definitions under high humidity exposure and to explore the additive effect of high humidity on cardiovascular disease mortality from heat wave and cold spell.Results: 1.Heat wave or cold spell and basic characteristics of CVD mortality: Among 2017-2020,heat wave mainly occurred in August,with an average of 6 to 34 days per year for heat wave days;Cold spell mainly occurred in January,with an average of 5 to 34 days per year for cold spell days.The average relative humidity was above 70% in a in high humidity regions in 2017-2020.High humidity was defined as relative humidity greater than 70%,and high humidity weather ranged from 198 to 250 days per year.Average daily cardiovascular mortality ranged from 34 to 52 in per city.From 2017 to 2020,the burden of cardiovascular disease in Hunan Province is increasing year by year,and men are more affected than women.2.Heat wave and the risk of mortality for CVD mortality: heat wave was positively associated with cardiovascular disease mortality under different definitions.Heat waves with two consecutive days above the92.5th percentile of daily mean temperature was the best model fit with an RR value of 1.068(95% CI: 1.018,1.021)for risk of cardiovascular disease mortality.Under the best definition,heat wave was positively associated with cardiovascular disease mortality risk.With high humidity exposure,there was no association between heat wave and CVD mortality when lag0-7 days,with an RR value of 0.950(95% CI: 0.849,1.062).3.Cold spell and the risk of mortality for CVD mortality: cold spell was positively associated or not associated with cardiovascular disease mortality under different definitions.A cold spell with a 2.5 quartile model below the daily mean temperature for four consecutive days was the best model fit with an RR value of 1.827(95% CI: 1.261,2.646)for risk of cardiovascular disease mortality.Under the best definition,heat wave was positively associated with cardiovascular disease mortality risk.when lag0-28 days,cold spell increased the risk of CVD mortality with a statistically significant result,with an RR value of 1.535(95% CI: 1.195,1.972)with high humidity exposure.Conclusions: Heat and cold waves have become important factors in cardiovascular mortality in Hunan Province,and high humidity exposure significantly increases the association between cold waves and cardiovascular mortality.It implies that when developing low-temperature warnings,policymakers should fully consider the impact of humidity.Take measures to counteract the effects of cold waves and reduce the occurrence of adverse events such as cardiovascular disease in individuals at risk risk.