Were neighborhood trees and buildings linked to heat-related mortality in older adults?

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As climate change makes heat extremes more frequent, heat-related health risks are increasing, particularly for older adults. Within cities, environmental characteristics can modify heat exposure. Accessible indicators such as tree canopy coverage (TCC) and building fraction (BF) may help researchers understand how residential environments shape heat-related mortality and support equitable climate adaptation.

The study examined associations between neighborhood TCC, BF and heat-related mortality among adults aged 65 years and older, using daily maximum air temperature as the exposure. It covered Sweden’s three largest urban areas—Stockholm, Gothenburg and Malmö—from 2006 to 2019. Researchers analyzed daily all-cause mortality using distributed lag non-linear models (DLNMs), with a lag of 0–4 days. Analyses were aggregated by high and low levels of TCC and BF. Heat-related mortality was calculated at both the 99th temperature percentile (28.1–29.0 °C) and 30 °C, and compared with the minimum mortality temperature (MMT) to estimate relative risk (RR).

Compared with the MMT, overall mortality was 15–17% higher at the 99th percentile and 24–32% higher at 30 °C. The results also suggested a trend toward higher heat-related mortality in neighborhoods with low TCC and high BF than in areas with high TCC and low BF, with relative risk differences of 4–21% for TCC and 0–22% for BF. The authors say the findings highlight the importance of the residential urban environment for protecting older adults during heat extremes and support using simple indicators to inform equitable urban health and climate adaptation strategies.