Lingering pollution menace, ozone, gets renewed scrutiny

Declines in PM2.5 trigger rise in gas at ground level as natural sponge is lost

China's top environmental watchdog has vowed to take more steps to help reduce ozone pollution, as ground-level ozone is the only one of six major pollutants that is rising in China.

The six include air pollutants such as nitrogen oxide, sulfur dioxide and PM2.5. The ozone experienced a rise in density in the country's 338 major cities in 2018. The concentration averaged 151 micrograms per cubic meter last year, up by 1.3 percent year-on-year, according to the Ministry of Ecology and Environment.