Ozone and cold spells jointly associated with higher AIDS-related mortality in China

Researchers examined long-term ozone exposure and cold-spell frequency in a population-based open cohort of 28,140 people living with HIV/AIDS in Hubei Province, China, from 2001 to 2020. Annual ozone exposure was estimated using high-resolution gridded data, and cold spells were defined as at least two consecutive days with mean temperatures below the county-specific 10th percentile. Time-varying Cox models assessed associations with AIDS-related mortality.

During 132,353.9 person-years of follow-up, 2,023 AIDS-related deaths occurred. Each 8.8-ppb interquartile-range increase in ozone exposure was associated with a hazard ratio of 1.15 (95% CI, 1.08–1.23). Each 17-day interquartile-range increase in cold-spell frequency was associated with a hazard ratio of 1.18 (95% CI, 1.10–1.26). The reported interaction hazard ratio was 1.89 (95% CI, 1.58–2.26), with a relative excess risk due to interaction of 0.63 (95% CI, 0.48–0.78), supporting additional risk from joint exposure.

The findings suggest that multiple environmental stressors warrant consideration in HIV care and public-health planning. However, this observational study cannot establish causation, and findings from one Chinese province may not generalize to other populations. Environmental exposures were estimated rather than individually measured; sensitivity analyses included exposure-misclassification correction and placebo tests.