Asthma mortality attributable to ambient temperatures: A case-crossover study in China

Area of Science:

• Environmental Epidemiology
• Public Health
• Respiratory Medicine

Background:

• The impact of ambient temperature on asthma mortality is not well understood.
• A quantitative evaluation of ambient temperature's association with asthma deaths was lacking.

Purpose of the Study:

• To assess the association between ambient temperature exposure and asthma mortality in China.
• To quantify the burden of asthma deaths attributable to non-optimum ambient temperatures.

Main Methods:

• A time-stratified case-crossover study was conducted using data from China's National Mortality Surveillance System (2015-2019).
• 15,888 asthma deaths were analyzed, with individual exposure to air and apparent temperature assessed.
• Distributed lag nonlinear models were employed to determine exposure-response relationships.

Main Results:

• A reverse J-shaped association was found between air temperature and asthma mortality risk, with a minimum mortality temperature of 21.3°C.
• Non-optimum ambient temperatures accounted for 26.3% of total asthma mortality.
• Moderate cold temperatures (21.7%) were the largest contributor, followed by moderate hot (2.4%), extreme cold (2.1%), and extreme hot (0.9%).

Conclusions:

• Exposure to non-optimum ambient temperatures, especially moderate cold, significantly increases asthma mortality.
• Findings highlight the need for public health interventions to reduce adverse respiratory effects of temperature variations.