Temperature modifies the association between air pollution and respiratory disease mortality in Cape Town, South Africa.

The aim of this 10-year study was to investigate whether and how temperature modifies the association between daily ambient PM 10 , NO 2, SO 2 air pollution and daily respiratory disease mortality in Cape Town. A time-stratified case-crossover epidemiological design was applied. Susceptibility by sex and age groups (15-64 years and ≥65 years) was also investigated. On days with medium Tapp levels, NO 2 displayed a stronger association with respiratory mortality than PM 10 or SO 2 . Females appeared to be more susceptible to NO 2 at medium Tapp levels to males. The 15-64-year-old age group seemed to be more vulnerable to NO 2 and PM 10 at medium Tapp levels compared to the elderly (≥65 years). At high Tapp levels, females were more susceptible to PM 10 . The 15-64-year-old group were more vulnerable to NO 2 and SO 2 . The results can be used in present-day early warning systems and in risk assessments to estimate the impact of increased air pollution and temperature.