The role of absolute humidity in respiratory mortality in Guangzhou, a hot and wet city of South China

Abstract

Background For the reason that many studies have been inconclusive on the effect of humidity on respiratory disease, we examined the association between absolute humidity and respiratory disease mortality and quantified the mortality burden due to non-optimal absolute humidity in Guangzhou, China. Methods Daily respiratory disease mortality including total 42,440 deaths from 1 February 2013 to 31 December 2018 and meteorological data of the same period in Guangzhou City were collected. The distributed lag non-linear model was used to determine the optimal absolute humidity of death and discuss their non-linear lagged effects. Attributable fraction and population attributable mortality were calculated based on the optimal absolute humidity, defined as the minimum mortality absolute humidity. Results The association between absolute humidity and total respiratory disease mortality showed an M-shaped non-linear curve. In total, 21.57% (95% CI 14.20 ~ 27.75%) of respiratory disease mortality (9154 deaths) was attributable to non-optimum absolute humidity. The attributable fractions due to high absolute humidity were 13.49% (95% CI 9.56 ~ 16.98%), while mortality burden of low absolute humidity were 8.08% (95% CI 0.89 ~ 13.93%), respectively. Extreme dry and moist absolute humidity accounted for total respiratory disease mortality fraction of 0.87% (95% CI − 0.09 ~ 1.58%) and 0.91% (95% CI 0.25 ~ 1.39%), respectively. There was no significant gender and age difference in the burden of attributable risk due to absolute humidity. Conclusions Our study showed that both high and low absolute humidity are responsible for considerable respiratory disease mortality burden, the component attributed to the high absolute humidity effect is greater. Our results may have important implications for the development of public health measures to reduce respiratory disease mortality.

Análise da inter-relação entre a sazonalidade climática e as doenças respiratórias

“…A alta umidade e o calor ambiente são responsáveis por favorecer a deposição de aerossóis submicrônicos e aerossóis infecciosos no trato respiratório, associando-se ao aumento de infecções respiratórias, asma e doença pulmonar obstrutiva crônica. (Chen et al, 2021;Moraes et al, 2019).…”

“…A baixa umidade está relacionada com a desidratação e agravamento de doenças respiratórias pré-existentes, enquanto que a alta umidade, em casos graves, devido à troca de calor inapropriada com o meio ambiente, pode evoluir com síncope pelo calor, cãibras de calor e exaustão, levando à morte. Umidades abaixo de 20% representam um estado de alerta e emergência para acometimento de doenças respiratórias (Chen et al, 2021).…”

Post-Sunset Humid-Heat Maxima near the Southern Persian/Arabian Gulf

“…We refrain here from weighing in on the debate about whether any one metric is categorically preferable to any other for determining impacts to human health and wellbeing, but simply note that each metric has distinct applications and a substantial body of literature supporting it 18,31,34 . Furthermore, very high speci c humidity raises health concerns on its own, such as a link with respiratory mortality found in southern China that is likely due to a combination of breathing di culties, increased infections, and broadly elevated heat-stress risk 35 . Metric choice is not the only source of difference or uncertainty around representing humid heat in the greater Arabia region.…”

Estimating mortality associated with seasonal influenza among adults aged 65 years and above in China from 2011 to 2016: A systematic review and model analysis

“…56,57 In addition, the high absolute humidity might exacerbate the mortality burden. [58][59][60] Likewise, the lowest excess R&C and AC mortality burden in Tianjin, Beijing, and Shanghai municipalities would be related to their low proportion of rural residents. In addition, higher socioeconomic development, better medical resources, and higher influenza vaccine coverage might contribute to the low mortality.…”

“…The high outpatient burden might indicate high influenza virus activity in Guangdong Province, which causes a high mortality burden 56,57 . In addition, the high absolute humidity might exacerbate the mortality burden 58–60 …”