Extreme temperature exposure and incident chronic lung disease among middle-aged and older adults in china: a longitudinal cohort study

To examine the associations of cold spell and heat wave exposure across varying intensities and durations with incident chronic lung disease among middle-aged and older adults in China. This prospective cohort study used data from five waves (2011–2020) of CHARLS (N = 9,458). Fifty exposure metrics were constructed by crossing temperature percentile thresholds (cold spells: P2.5–P10; heat waves: P85–P97.5) with duration windows (≥ 1 to ≥ 5 days). Associations were analyzed using GLMMs with BH-FDR correction, restricted cubic spline models, subgroup analyses, and comprehensive sensitivity analyses including Cox, Fine-Gray competing risk models, and fixed exposure window validation. Over a median 7.0-year follow-up, 1,562 cases occurred (incidence: 16.51%). All 50 metrics were significantly associated with increased risk (all FDR-adjusted P < 0.01). At ≥ 5 days, P10 cold spells (OR = 1.34, 95% CI: 1.27–1.42) and P85 heat waves (OR = 1.32, 1.25–1.40) exceeded more extreme counterparts (P2.5: 1.13, 1.07–1.20; P97.5: 1.20, 1.13–1.27). Cold spells exhibited nonlinear exposure–response patterns (P5: P-non-linearity < 0.001), while heat waves showed linear patterns (P90–P97.5: all P-non-linearity > 0.50). Residence was the only effect modifier identified in the reported FDR-adjusted interaction results for cold spells (adjusted P-interaction = 0.042). Cox (HR = 1.28, 1.22–1.35) and Fine-Gray (sHR = 1.26, 1.20–1.33) models yielded directionally consistent associations. Both cold spells and heat waves were associated with increased chronic lung disease incidence. Frequent moderate events may impose a greater cumulative burden than rare extreme events, while the association with cold spells was stronger among rural residents. These findings highlight the need for climate-health assessments and adaptation strategies to address cumulative exposure and population-specific differences.