Mega-Events, Air Pollution and Health Outcomes: A Systematic Review

Mega-events can create changes in air quality, offering quasi-experimental settings to synthesise evidence on pollutant shifts and the associated short‑term health effects. We systematically reviewed 31 studies (PROSPERO CRD420251032553) from four databases up to 7 April 2025. Fourteen studies assessed mortality/hospitalisation outcomes. A 10 μg/m3 decrease in PM10 during emission-control periods was associated with 8.4-9.6% lower all-cause mortality and 8.8% lower cardiovascular mortality. Whereas each 10 μg/m3 increase in NO2 and O3 increased total mortality by 1.89 % (95% C.I. 1.49-2.29) and 0.60 % (95% C.I.: 0.47- 0.74), and increases raised cardiovascular mortality by 4.42 % (95% C.I.: 3.16-5.69). Seventeen studies assessed early biological responses via human biomonitoring. Reduction in PM2.5, NO2 and O3 during emission control-measures were consistently associated with reduced circulating levels of ICAM-1, VCAM-1 and IL-1β, reduced in pulmonary-inflammatory and oxidative stress markers (FeNO, 8-isoprostane), systemic-inflammation/oxidative-stress markers (von-Willebrand-factor “vWf”, urinary-8-OHdG, Malondialdehyde), as well as haemostasis/platelet-activation markers (sCD40L, sCD62P) and improvement in cardiovascular measures (heart-rate, systolic BP), which increased again after controls ended, and similar decreases and rebounds were seen for fibrinogen, vWF, sCD62P, sCD40L when pollutants decreased by 13-60% and later returned to pre‑Olympic levels. Mega‑events show that emission-control lower mortality and improve inflammatory and oxidative stress responses suggesting the need for increasingly spread urban planning and event‑management policies to protect Public Health.

Key messages

• Mega-events affect air pollution levels, which in turn may cause a higher mortality rate and hospitalisations in local population. This may be prevented by emission controls policies.

• Early biological responses like oxidative stress and inflammation can be modulated by air pollution fluctuations related to mega-events. Human biomonitoring can support prevention in Public Health.