A stone lion on a bridge in Tianjin is covered with a mask in the heavy smog that has hit much of the country's northern regions.

China's environment minister said he "felt guilty" and "wanted to reproach himself" as widespread air pollution has harassed people's lives, an official statement said Saturday.

Chen Jining, minister of environmental protection, made the remarks when holding a press conference late on Friday in Beijing, introducing China's efforts on air pollution prevention.

Since the beginning of last winter, heavy air pollution has happened repeatedly in many places in China, covering large area and lasting long, which disrupted production activities and harassed people's everyday lives, Chen said.

The public felt anxious about the smog problem, he said.

Detailed analysis showed emissions from automobiles have became the primary source of urban atmospheric fine particles in major cities, accounting for 31.3 percent in Beijing, 29.2 percent in Shanghai and 28 percent in Hangzhou, according to the environment minister.

Fine particles are defined by the U.S. Environmental Protection Agency as compounds that have a diameter of less than or equal to 2.5 micrometers. Substances that may form these particles come from power plants, industrial facilities, agricultural practices, motor vehicles, among others.

Chen said the ministry was evaluating 20 cities' emergency plans in dealing with heavy air pollution, hoping to improve their response ability.

The cities include Beijing, Tianjin and 18 other cities in Hebei and surrounding provinces.

Inspections had found some cities failing to take effective measures following alerts, or their measures were impracticable, Chen said.

The ministry will enhance supervision on whether local governments have practiced its precautions, according to the minister.

Chen vowed to take concrete steps and employ more stringent and effective measures to deal with outstanding environmental problems and improve environment quality.

China has been cleaning its environment and will continue to improve the response of local governments to pollution, Chen said.