The current heat is not only a strain on the circulatory system and especially for older people, it also leads to ozone levels on the ground, some of which are questionable. While According to the Federal Environment Agency (UBA) until mid-July the information threshold of 180 micrograms of ozone per cubic meter had only been exceeded for a total of 16 hours, on Monday alone 15 measuring stations reported exceedances for a total of 33 hours.
A warning is issued from a value of 240 micrograms per cubic meter because such high ozone concentrations are hazardous to the health of the entire population. According to the UBA forecast from Tuesday morning, numerous other exceedances of the information value were to be expected on both Tuesday and Wednesday, especially on Tuesday in North Rhine-Westphalia and on Wednesday in Hesse. But also in Lower Saxony and Baden-Württemberg, the threshold is likely to be exceeded in many places, typically from the late afternoon, in the morning and in the evening the load is lower. Individual exceeding of the warning threshold of 240 micrograms cannot be ruled out.
The ozone molecule O₃, which, unlike harmless oxygen molecules, consists of three instead of two oxygen atoms, has positive and negative effects on humans. The ozone layer in the stratosphere above an altitude of around 15 kilometers protects against UV radiation. However, in deeper layers, ozone is a greenhouse gas, and on the ground it acts as an air pollutant that can affect sensitive people even in medium concentrations and is unhealthy for everyone in high concentrations.
The pollution is often higher on the outskirts than in the center
Heat and strong sunlight drive ozone formation, so the increased levels are clearly related to the heat wave. Ozone is formed, for example, when sunlight hits nitrogen dioxide, especially from traffic, or volatile organic compounds, for example from solvents. However, the pollution is often higher outside the city center because nitrogen dioxide is also present on the outskirts or in neighboring areas, while in the center the ozone is broken down again by other exhaust gas pollutants such as nitrogen monoxide.
Also the scientists of the European earth observation program Copernicus warned on Tuesday that the very high ozone pollution in southern Europe could now spread to the north-west. In the past week, values above 200 micrograms per cubic meter were measured, especially over the Iberian Peninsula and in northern Italy. According to Copernicus data, concentrations in northern and western Europe have increased to more than 120 micrograms per cubic meter since Monday. The scientists expect the highest values by Wednesday, after which the load should decrease again.
Elevated ozone levels can cause a sore throat, cough or headache and increase the risk of asthma attacks. Especially after outdoor sports, the lung function and physical performance can be reduced in school children and adults. Normally these restrictions recede after two days at the latest, but it can occur especially during physical exertionthat ozone causes inflammatory changes in lung tissue. Elevated ground-level ozone levels are also a factor in cardiovascular disease. the lancet Commission on Pollution and Health estimates that 370,000 premature deaths are caused by ozone exposure each year.