BEIJING, Aug. 11 (Xinhua) -- Chinese and foreign researchers have revealed the effects of night-time warming on mortality burden, publishing their findings in the Lancet Planetary Health.
"The health impacts of climate warming are usually quantified based on daily average temperatures, while little is studied on the extra health risks resulting from hot nights," said Kan Haidong, professor at the School of Public Health, Fudan University.
Researchers have collected historical mortality data in 28 cities from China, the Republic of Korea and Japan from 1981 to 2010, and selected the hot night excess (HNE) to represent the intensity of night-time heat, which was calculated as the excess sum of high temperature during night time.
They then examined the associations between HNE and mortality in each city by using a generalized additive model, according to the paper.
The time-series analysis showed the HNE was significantly associated with increased mortality risks, the relative mortality risk on days with hot nights could be 50 percent higher than on days with non-hot nights, the paper said.
"Our findings suggest a growing role of night-time warming in heat-related health effects in a changing climate," said Kan.