An official report detailed that the density of hazardous PM2.5 dropped to 30 micrograms per cubic meter nationwide and improvements were seen in the containment of acid rain, both important indicators for measuring air quality.

However, ozone levels increased 137 micrograms per cubic meter throughout the country, especially in summer.

According to authorities of the Ministry of Ecology and Environment, the gas rises more when the temperature is high and the sun is more intense.

China has reduced air pollution levels in several cities by 40 percent in the last five years through measures such as the closure of coal-fired plants, restrictions on vehicle traffic and the use of natural gas.

PM2.5 absorbs the elements responsible for generating ozone and by lowering it increased the presence of the chemical in the lower levels of the atmosphere.

Breathing air with a high concentration of this gas is highly harmful for asthmatics, children, the elderly, athletes and those who work outdoors.

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