The burden of influenza and pneumonia mortality attributable to absolute humidity among elderly people in Chongqing, China, 2012–2018

To examine the association between absolute humidity (AH) and influenza and pneumonia (P&I) mortality, and to quantify P&I mortality burden attributable to non-optimum AHs among elderly people aged ≥65 years in Chongqing, the largest municipality of China. Daily data of P&I mortality from 2012 to 2018, and the contemporaneous meteorological data in the study area were collected. Distributed lag non-linear model (DLNM) was applied to estimate the non-linear and delayed effects of absolute humidity (AH) on P&I mortality. Then, attributable deaths were calculated for the dry and moist AH, defined as AH below and above the minimum mortality AH (MMAH), respectively. Moderate and extreme AHs were defined using cutoffs at the 2.5th and 97.5th percentiles of AH. The relationship between AH and P&I mortality was a U-shaped curve. The MMAH was 11.5 g/m3 (46.4th percentile). In total, 25.7% (95% confidence interval: 10.0–38.2) of P&I mortality (4673 deaths) was attributed to non-optimum AHs. Low AHs were responsible for 12.7% of the P&I death burden (95%CI: 0.2–20.1), while high AHs for 13.0% (95%CI: −9.4–25.7). Extreme low and high AHs accounted for 3.7% (95%CI: 0.1–6.8) and 3.0% (95%CI: 0–5.4) of P&I mortality. Our study showed that both low AHs and high AHs are responsible for considerable AH-related P&I mortality burden among elderly people. Our results may have important public health implications for the development of relevant intervention policies to reduce P&I deaths among the elderly. [Display omitted] •Absolute humidity (AH) has a significant impact on influenza and pneumonia (P&I) mortality among elderly people.•The relationship between AH and P&I mortality showed a U-shaped curve.•Approximately a quarter of P&I mortality (25.7%) was attributed to non-optimum AHs.