A week of high temperatures in northern China will result in increased levels of ground-level ozone, a dangerous air pollutant, environment officials said on Sunday.
The spike will be caused by a heatwave that is forecast to hit Beijing, Tianjin and the neighbouring provinces of Hebei, Henan and Shandong, combined with a wind from the south, the Ministry of Ecology and Environment said.
As a result, cities in the affected areas will experience light to medium air pollution – with air quality index readings of 100 to 200 – through June 11, it said.
The situation might improve in some areas by Friday, however, with the arrival of a cold front or rain, the ministry said.
Ozone is one of six components of China’s official air quality index, along with sulphur dioxide, nitrogen oxide, carbon monoxide, and the airborne particles known as PM2.5 and PM10.
Ground-level ozone is produced mainly by the emission of volatile organic compounds and nitrogen oxide interacting with sunlight. High temperatures and strong sunlight are also important factors.
Studies have shown that exposure to ozone is damaging to the lungs, respiratory tract and eyes.
Liu Zhiquan, head of the ministry’s monitoring department, was quoted by Xinhua as saying that in China ground-level ozone pollution was most common in Beijing, Tianjin and Hebei.
However, it was not often that concentrations of the pollutant reached dangerous levels and it would be relatively easy for the public to avoid the worst of it, he said.
Meanwhile, a study by Peking University’s Guanghua School of Management and the Centre for Statistical Science of pollution in 33 northern cities found that although PM2.5 concentrations fell in the 2013-17 period, average daytime ozone levels jumped sharply.
In 10 of the cities monitored, concentrations of the pollutant rose by at least 40 per cent, the research said.