Heat waves and cause-specific mortality at all ages.

Area of Science:

• Environmental Health
• Public Health
• Epidemiology

Background:

• Extreme ambient temperatures are linked to increased mortality.
• Infants are a vulnerable population to heat, yet specific mortality causes are understudied.
• Understanding heat-related mortality causes is crucial for effective public health policies.

Purpose of the Study:

• To investigate the association between extreme heat and cause-specific mortality.
• To quantify the impact of heat on total and infant mortality in Catalonia, Spain.
• To identify vulnerable infant populations and critical time windows during heat events.

Main Methods:

• Case-crossover design analyzing 503,389 deaths in Catalonia (1983-2006).
• Defined extreme heat days as those exceeding the 95th temperature percentile.
• Stratified total mortality (66 causes) and infant mortality (8 causes) by heat exposure.

Main Results:

• Three consecutive hot days increased total mortality by 19%; 1.6% of all deaths were heat-attributable.
• Heat increased deaths from cardiovascular, respiratory, infectious, digestive, and nervous system diseases, and suicide.
• Infant mortality showed a 1.53 relative risk on the same day, primarily from perinatal conditions (cardiovascular, respiratory, digestive, hematologic disorders).

Conclusions:

• Heat exposure contributes to increased mortality across multiple causes.
• The first week of life represents the most critical period of vulnerability for infants during heat events.
• Findings underscore the need for targeted public health interventions during extreme heat.