Air quality in several Chinese cities got worse in October, according to statistics from China's environmental watchdog on Monday.

According to statistics released by the Ministry of Environmental Protection, the number of days in the Oct. with air quality of a decent standard in the Beijing-Tianjin-Hebei region dropped by 25.4 percent, compared to the figure of the previous month.

Beijing suffered from ten days of "heavy" or "serious" air pollution, according to the ministry's report.

Cities in the Yangtze River Delta and the Pearl River Delta regions also witnessed poorer air quality in Oct., it said.

In the 74 cities monitored, the major pollutant is PM2.5, followed by ozone, the report said.