Air pollution and exercise

Athletes may be at special risk of an increased dose of pollutants compared to sedentary individuals because of their close proximity to pollutant sources for long periods of time during training and competition. There are also exercise-mediated increases in minute ventilation, airflow velocity and oral rather than nasal breathing which may increase an athlete's dose of pollutants as well as a post-exercise impairment in upper airway mucociliary action which removes pollutants. Ambient levels of ozone, benzene and particulate matter of less than 10 μm (PM-10s) are periodically high in most developed countries. The typical levels of ozone in the summer months in the UK would be predicted to impair exercise performance. More research work is needed to establish the effects of ambient levels of benzene and PM-10s on performance. Cyclists and road-runners training in environments with less than 6 ppm of carbon monoxide (CO) and in countries that have reduced the amount of lead in petrol to below 0.4 g/l are unlikely to absorb significant amounts of these pollutants. Competitive shooters can be exposed to high amounts of lead in indoor firing ranges. Sports competitors in ice arenas have been found to be at substantial risk of inhalation of CO and nitrogen dioxide emitted from the ice-maintenance machines. Caution should be exerted by mountaineers when gas stoves are used in, tents or ice-holes, since CO levels can increase markedly. Scuba divers should ensure their compressed air is not contaminated by urban pollution. Mitigation should centre around the avoidance of peak-times and areas of air pollution prior to and during training and competition and, in indoor sports arenas, the provision of adequate ventilation systems and limitation of the use of mineral-driven maintenance machines. The regular monitoring of both ambient levels and body-burdens of pollutants is also recommended. Athletes and coaches should also be encouraged to consult the 'real-time' pollution information sources that are available.