China experienced an uptick in ozone pollution in the first five months of this year, and is likely to be hit by more in the coming three months due to unfavorable meteorological conditions, according to the Ministry of Ecology and Environment.

From January to May, the average concentration of ozone across the country stood at 140 micrograms per cubic meter, up by 0.7 percent from the same period last year, said Pei Xiaofei, a spokesman for the ministry, in a recent news conference.

In total, prefecture-level cities across the country reported 2,480 days with average ozone concentrations beyond the national standard of 140 micrograms per cubic meter, surpassing levels recorded during comparable historical periods, he said.

The ozone layer, which is about 20 kilometers above the Earth's surface, helps shield the planet from harmful ultraviolet radiation. Near the ground, however, even relatively low amounts of ozone can cause lung damage and result in shortness of breath.

Pei said ozone pollution occurred in the country much earlier this year with much more expansive coverage.

On March 26, ozone pollution exceeding the national standard occurred in 80 cities across the country, a month earlier compared to the typical historical trend, Pei said.

From May 26 to 30, over 100 cities experienced prolonged periods of high ozone levels for five consecutive days, signaling a significantly broader impact this year compared to previous years.

Southern parts of the country suffered much more severe problems due to higher-than-average temperatures and reduced rainfall, which created unfavorable meteorological conditions for the generation of ozone, and the persistently high emissions of volatile organic compounds and nitrogen oxides.

High concentrations of ozone usually occur during hot periods. Sunlight and high temperatures can trigger chemical reactions between volatile organic compounds and nitrogen oxides that lead to the formation of ozone. Vehicle exhaust, for example, is one of the major contributors to the two types of substances. The combustion of fuels such as coal and oil generates significant amounts of nitrogen oxides.

Pei warned that more ozone pollution may occur across the country from June to September.

He pointed out that a collaborative consultation between the National Climate Center and the China Environmental Monitoring Station revealed that temperatures in most parts of the country are projected to be above average for June to September, leading to meteorological conditions that are more conducive to the formation of ozone pollution.

Despite the situation this year, the official said, "Overall, the rising trend of ozone pollution in China has been preliminarily curbed, and its density has stabilized in the past three years."

According to the ministry, the average concentration of ozone in the 339 prefecture-level cities and above across the country reached 145 micrograms per cubic meter in 2022, up by 5.8 percent year-on-year. In 2023 and 2024, the density stood at 144 micrograms per cubic meter for the two years.

Pei said the ministry was taking a series of measures to increase ozone pollution control this year.

The ministry plans to enhance its air quality monitoring networks, with a specific focus on photochemical monitoring that tracks chemical reactions in the atmosphere triggered by sunlight.

By closely monitoring the fluctuations in ozone levels and their precursor compounds, including volatile organic compounds and nitrogen oxides, the ministry aims to enhance its forecasting and predictive capabilities for ozone pollution.

"The ministry will continue its investigations into violations related to volatile organic compound emissions and implement measures to facilitate their rectification," he said.

From January to April, he said, the ministry combed through over 5,900 companies across the country and found almost 10,400 violations, of which 9,530 have been rectified.

He underscored the ultralow emissions in smokestack industries, including crude steel and coking, as one of the priorities for the ministry, as the efforts can synergize the control of fine particulate matter and ozone.

Noting motor vehicle emissions as a major nitrogen oxide contributor, he said consistent efforts from the ministry have cracked down on violations.

Last year, the ministry, together with five national government bodies, jointly launched a campaign targeting data falsification in such emissions inspections, and in May this year, it issued a guideline with another eight departments to further optimize environmental supervision over motor vehicles, he said.

Pei said the ministry will prioritize the management of heavy-duty trucks and the oversight of inspection and maintenance institutions, taking strict action against excessive emissions and emission data falsification.

"The efforts aim to curb pollutant emissions and continually strengthen the public's sense of well-being fostered by cleaner air and bluer skies," he said.