A multitude of epidemiological studies have demonstrated that both ambient temperatures and air pollution are closely related to health outcomes. However, whether temperature has modi cation effects on the association between ozone and health outcomes is still debated. In this study, Three parallel timeseries Poisson generalized additive models (GAMs) were used to examine the effects of modifying ambient temperatures on the association between ozone and mortality (including non-accidental, respiratory, and cardiovascular mortality) in Chengdu, China, from 2014 to 2016. The results con rmed that the ambient high temperatures strongly ampli ed the adverse effects of ozone on human mortality; speci cally, the ozone effects were most pronounced at >28°C. Without temperature strati cation conditions, a 10-µg/m 3 increase in the maximum 8-hour average ozone (O 3−8hmax ) level at lag01 was associated with increases of 0.40% (95% con dence interval [CI]: 0.15%, 0.65%), 0.61% (95%CI: 0.27%, 0.95%) and 0.69% (95%CI: 0.34%, 1.04%) in non-accidental, respiratory, and cardiovascular mortality, respectively. On days during which the temperature exceeded 28°C, a 10-µg/m 3 increase in O 3−8hmax led to increases of 2.22% (95%CI: 1.21%, 3.23%), 2.67% (95%CI: 0.57%, 4.76%), and 4.13% (95%CI: 2.34%, 5.92%) in non-accidental, respiratory, and cardiovascular mortality, respectively. Our ndings validated that high temperature could further aggravate the health risks of O 3−8hmax , thus mitigating ozone exposure will be brought into the limelight especially under the context of changing climate.
