The impact of air pollution on cardiovascular and respiratory mortality in makkah, Saudi Arabia, during the Hajj cultural events and COVID-19 outbreak

Abstract Air pollution remains a global issue impacting the environment and public health, yet its effects during cultural events remain under-recognised. This study investigated the relationship between selected air pollutants (PM ₁₀ , NO ₂ , O ₃ , SO ₂ ) and cardiovascular and respiratory mortality rates from 2018 to 2022, specifically during the Hajj cultural events in Makkah, Saudi Arabia. Time series log-linear models assessed the relationship between monthly air pollutants and cardiovascular and respiratory mortality. We adjusted for season and trend and tested an interaction model for effect modification of Hajj cultural events and COVID-19 on the air pollution mortality associations. A larger association was determined between NO ₂ and cardiovascular mortality during Hajj cultural events (RR: 1.17, 95% CI: 1.05–1.30) compared to non-Hajj periods (RR: 1.02, 95% CI: 0.99–1.05). The increased risk of respiratory mortality associated with NO ₂ during the Hajj cultural events was higher (RR: 1.24, 95% CI: 1.09–1.40) compared with the period with no Hajj events (RR: 1.04, 95% CI: 0.99–1.09). The study also found that exposure to increased levels of O ₃ also significantly impacted respiratory (RR:1.19, 95% CI: 1.04–1.48) and cardiovascular mortality (RR:1.35, 95% CI:1.15–1.59) during Hajj cultural events while an inverse association was observed between O ₃ and respiratory (RR:0.92, 95% CI: 0.89–0.96) and cardiovascular (RR:0.97, 95% CI: 0.94–0.99) mortality during non-Hajj periods. During COVID-19, the study showed that most associations were inverse or nonsignificant; only SO₂ showed a positive association with cardiovascular mortality (RR = 1.22; 95% CI: 1.11–1.34). The study outcomes provide valuable insights into the environmental health field, supporting policy development for public health protection.