Ozone and open air sport events

Due to weather conditions open air sport events normally take place in summer and throughout these summer months the ozone levels can be high. During physical exertion, we breathe faster and deeper, ozone enters the respiratory tract and lungs and thus adverse health effects can develop.

Sport event organisers should inform participants when ozone levels are high. In addition, elevated ozone levels should also be reported via the media if certain thresholds are exceeded. However, it is left up to the participants themselves to decide whether to participate in a sport event or not. The following information is provided in order to help you to reach a decision.

In their air quality guidelines the World Health Organization (WHO) recommends a guideline value of 100 μg/m³ ozone (8-hour average) for health protection. The EU Directive 2008/50/EC "Ambient Air Quality and Cleaner Air for Europe" sets the following target: the maximum 8-hour value of a day may not exceed 120 µg/m³ on more than 25 days per calendar year (averaged over 3 years). An “information threshold” of 180 μg/m³ (1 hour value) and an “alarm threshold” of 240 μg/m³ (1 hour value) is in force. The EU Directive found its implementation in German Immission Control Law. According to this regulation, the general public has to be informed about the risks of outdoor physical activities when ozone values exceed 180 µg/m³. People with a “known sensitivity to ozone” are advised to avoid unfamiliar and intensive physical exercise especially in the afternoon.

No specific advice relating to sporting events is given by the local authorities. However, there are some recommendations regarding school sports: to be more attentive when ozone values are higher than180 µg/m³ i.e. to avoid endurance training, to take extra care of children who are particularly sensitive to ozone, to excuse asthmatic children from school sports and to postpone any competitions or festivals.

Some federal and local authorities do advise to take more precautionary measures, for example, Saxony recommends adjusting sports lessons when the ozone values reach 150 μg/m³ and in Essen endurance training should be avoided in the afternoon when a value of 120 μg/m³ (1-hour value) or higher is reached.

We consider the adoption of precautionary measures as justified and recommend to reconsider any participation in an open-air sport event if the one hour ozone value exceeds 120 µg/m³. This is important for sensitive people and especially for children with respiratory tract diseases. Taking action against summer heat and UV radiation also protects against elevated ozone concentrations: sport activities should not be carried out at noon or in the afternoon, not only because of the heat but also because of the high ozone concentrations.

Due to the lack of a current toxicological or epidemiological reassessment of the health effects of ozone our recommendations cannot be finalised. We therefore provisionally justify our recommendations according to precautionary principles of preventive health protection with the following scientific facts:

• In the VDI guideline 2310 (Association of German Engineers, 2001) a short-term MIK value (0.5 h) (Maximum Immission Concentration) for the protection of human health of 120 μg/m³ was defined. The VDI stated at the time that this value implies practically no safety margin for people who are sensitive to ozone during prolonged physical exercise outdoors.
• In the year 2000 the state of Baden-Württemberg developed a scientific based index system for the assessment of air quality. A 1-hour cut-off value of 120 μg/m³ was determined: If exceeded, ozone-sensitive people should reduce any outdoor physical activities.

• • The WHO published in 2013 an expert opinion (REVIHAAP) on the current EU air quality threshold and target values. The WHO experts recommended a reassessment of the health effects of ozone and noted that a short-term assessment value (1 h) for ozone would probably be below 90 μg/m³.