Air pollution and performances in outdoor sports: a systematic review and meta-analysis of short-terms associations

Laboratory studies suggest that high concentrations of particles matter (diameter<2.5 mm [PM2.5]) and ozone (O3) may reduce sport performances at short term. However, a systematic review of literature examining whether air pollution has an effect on sport performances in real situations is missing.Seven databases were searched for articles which examined the association between particulate (PM2.5, PM10, PMCoarse), gaseous (O3, sulfur dioxide [SO2], nitrogen dioxide [NO2], carbon monoxide [CO], and index (Air Quality Index [AQI]) of air pollutants and sport performances in real context. We included observational studies with objective measures of air pollution and performances. They were categorized into endurance, power/speed, technical performances. Harvest plots were used to summarize the findings. When appropriate, meta-analyses were completed to evaluate the strength of the associations. Over 200 reported associations from 23 articles were examined. Participants were primarily elite athletes. The majority of studies examined football (n = 9), and endurance sports (n = 10). Overall, no consistent associations were observed for AQI, PM2.5, or NO₂ and performances. We found that exposure to O3 was associated with reduced sports performance, (d = -0.33, 95%CI: -0.65 –0.02 [all performances]; d = -0.54, 95%CI: -1.02 -0.04) [endurance performances]). An absence of significant association between AQI, PM2.5, or NO2 exposure and sports performance is clearly supported by our systematic review and meta-analyses. Higher O3 concentration could impair sport performances in real context. For short-term exposures to CO, PM10, and SO₂, no definitive conclusions can be drawn due to the limited number of studies.