Ozone is multifaceted. Up in the stratosphere it protects us against harmful ultraviolet radiation from the sun, but too much ozone at ground level – i.e. in the air that we breathe – is undesirable. Intensive solar radiation during prolonged periods of hot summer weather regularly leads to high concentrations of ozone, which are hazardous to health and damage the environment. The ambient air quality standards stipulated in the Ordinance on Air Pollution Control (LRV) are still frequently exceeded in the summer months owing to the presence of nitrogen oxides (NOx) and volatile organic compounds (VOCs), the two precursors from which ozone is formed under the influence of sunlight. The primary sources of these precursors are road transport and also industry. The measures taken by the federal government to reduce summer smog are geared towards the long-term reduction of these precursors.
Current information on extremely high ozone levels
Current BPUK ozone bulletins
Besides providing general information, the Swiss Conference of Directors of Public Works, Planning and Environmental Protection (BPUK) notifies the population when ozone levels are extremely high. A bulletin is issued as soon as an ozone level of 180 µg/m3 is recorded in Switzerland. This reading is equivalent to one-and-a-half times the ozone impact threshold stipulated in the Swiss Ordinance on Air Pollution Control.
General information
Ozone pollution: Current levels and trends
Informations and links FOEN focusing on ozone and summer smog (in German or French)
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