Kunming is a plateau city with sufficient sunshine, high ultraviolet intensity, and strong radiation. In recent years, ozone (O₃) pollution has gradually become the primary problem of air pollution in the city.

To evaluate the health effects of atmospheric O₃ exposure on non-accidental deaths in Kunming.

The data of meteorological variables (average temperature, average relative humidity, average air pressure, and average wind speed), air pollutants (PM_2.5, PM₁₀, SO₂, CO, and O₃) and non-accidental deaths (NAD) of residents were collected in Kunming from 2017 to 2019. A generalized additive model was adopted to conduct time-series analyses on the current-day (lag0), single-day (lag1-lag3), and cumulative lag (lag01-lag03) effects of O₃ on NAD; furthermore, hierarchical analyses by gender, age, and season (warm and cold) were conducted.

The average concentration of O₃-8h from 2017 to 2019 was (84.3±32.3) μg·m⁻³. For every 10 μg·m⁻³ increase in O₃-8h concentration, the NAD risks of lag0, lag01, and lag02 of total population increased by 0.70% (95%CI: 0.11%-1.29%) 0.79% (95%CI: 0.14%-1.44%), and 0.75% (95%CI: 0.08%-1.43%), respectively; for women, the NAD risks of lag2 and lag02 increased by 0.80% (95%CI: 0.08%-1.53%) and 1.05% (95%CI: 0.09%-2.03%) respectively; for the residents over the age of 65, the associated NAD risks of lag0, lag01, and lag02 increased by 0.82% (95%CI: 0.16%-1.48%), 0.93% (95%CI: 0.20%-1.67%), and 0.96% (95%CI: 0.20%-1.73%), respectively; in the warm season, the NAD risks of lag0, lag01, and lag02 increased by 0.91% (95%CI: 0.12%-1.70%), 0.98% (95%CI: 0.12%-1.86%), and 1.00% (95%CI: 0.07%-1.93%), respectively; After introducing PM_2.5, PM₁₀, SO₂, NO₂, and CO to the model, the effects of O₃ exposure level on resident’s NAD was not statistically significant.

An increase of O₃ exposure level associates with an increase of NAD risk in residents, and there is a lag effect. Residents over the age of 65, women, and all residents in warm season may be more sensitive to O₃ exposure.