Abstract
BACKGROUND: The health effects of fine particulate matter (PM(2.5)) may be worse at higher temperatures. OBJECTIVE: To investigate temperature's effect on PM(2.5)-mortality/morbidity associations in Lima, Peru. METHODS: Time-series regressions relating PM(2.5) and temperature to mortality and emergency room (ER) visits during 2010-2016. Daily PM(2.5) levels (assigned to 40 Lima districts) and daily maximum temperature (Lima-wide) were estimated based on ground monitors, remote sensing, and modeling. We analyzed all-cause, cardiovascular (ICD codes I00-I99), and respiratory (ICD codes J00-J99) mortality, and cardiovascular and respiratory causes for ER visits. RESULTS: The average PM(2.5) concentration was 20.9 µg/m(3) (IQR 17.5-23.5). The mean daily maximum temperature was 23.8 °C (IQR 20.8-26.9). PM(2.5)'s effect on all-cause, respiratory, and circulatory disease mortality was significantly (p < 0.05) stronger at temperatures above the maximum temperature median. The rate ratios per increase of 10 µg/m(3) of PM(2.5) for all cause, respiratory, and circulatory mortality respectively were 1.03 (1.00-1.06), 1.04 (0.98-1.10), and 1.04 (0.98-1.10) at temperatures below the median, vs. 1.08 (1.04-1.12), 1.11 (1.03-1.19), and 1.14 (1.05-1.25) when temperatures were above the median. Results were analogous for ER visits for respiratory but not circulatory disease. SIGNIFICANCE: Results strengthen the evidence that air pollution may be more dangerous when temperatures are higher. IMPACT: Our data contribute to a growing body of literature which indicates that the damaging effects of PM(2.5) may be worse at higher temperature, adding new evidence from Lima, Peru.