Beijing Mayor Wang Anshun declared an "all-out effort" on Thursday to tackle air pollution by cutting coal use by 2.6 million tonnes and transforming 300 polluting companies this year .

Coal-burning boilers inside Beijing's fifth ring road will be eliminated and measures taken against coal burning in the capital's periphery, said Wang at the opening of the annual session of the municipal People's Congress, Beijing's legislature.

Four large gas-burning thermoelectricity centers will be completed, he said. The municipal government will earmark 15 billion yuan (2.4 billion U.S. dollars) to improve air quality in 2014.

Smog enveloped Beijing on Thursday. Air quality hit its most polluted level. Readings for PM 2.5, airborne particles smaller than 2.5 microns in diameter, exceeded 500 micrograms per cubic meter in most of the city at 6 a.m. on Thursday.

The municipal government issued a yellow smog alert at 7 a.m., as visibility in some parts of the city was forecast to be less than 500 meters. The haze will continue until Friday in Beijing.

The city aims to ban all heavily polluting vehicles this year, cut new car registrations and promote new energy vehicles. There will be research into pollutant reduction technology and the sources of PM2.5, Wang said.

In 2013, the city cut major air pollutants by more than 3 percent, replaced 366,000 old vehicles and overhauled 288 polluting factories.

However, Beijing still reported 58 days of serious pollution last year, or one every six to seven days on average, according to Zhang Dawei, director of the Beijing Municipal Environmental Monitoring Center.

The contribution of vehicle exhausts and lack of strong winds were contributory factors to the lingering of the smog, he said.

Beijing has begun coordinating and cooperating with its surrounding provinces to jointly deal with air pollution. The central government budgeted five billion yuan for air pollution control by Beijing and several of its neighbors in October.

The repeated bouts of hazy days since early 2013 have raised public complaints and prompted the government to take more effective steps.

In September, Beijing unveiled a five-year plan (2013- 2017)to improve air quality through measures such as cutting coal consumption, promoting clean energy use and reducing production capacities with heavy pollution.

The capital's 2013-2017 plan aims to cut annual coal consumption by 13 million tonnes and keep it within 10 million tonnes by 2017, compared with 23 million tonnes in 2012.

The city will slash its cement production capacity to 4 million tonnes in 2017, from 10 million tonnes in the early period of the 12th five-year development plan from 2011 to 2015.

Beijing's average PM2.5 index stood at 89.5 micrograms per cubic meter in 2013, more than double the new national standard of 35. The city only began monitoring for PM2.5 last year.

It still has a long way to go to realize the target of a yearly PM2.5 density of 60 micrograms per cubic meter in 2017.

A draft regulation on air pollution treatment and prevention will be reviewed at the legislative session. The regulation, the first of its kind for Beijing, includes emission controls on the total amounts of major air pollutants.

"These are different pollution treatment measures to be adopted in accordance with the distribution of current pollution sources," said Lu Jianru, a legal affairs official with the Beijing Environmental Protection Bureau.

A law should also be framed for promoting green energy, as the poor energy consumption structure has been an important factor causing smog, said Mao Daqing, vice president of Vanke Group, a leading property developer.

Technological barriers remain in place and general standards are lacking in the green energy sector, which needs government support, said Mao, also a member of the municipal political advisory body.

"The government has attached great importance to environmental problems in the past year, but there has been no final conclusion on the causes of smog," pointed out Wang Huiwen, professor in economics and management at Beihang University.

Relevant departments should conduct an in-depth study of the causes of smog and the sources of pollution in order to adjust industrial structure to control air pollutants, said Wang, also the city's political advisor.

"Technological tools should be used in air quality monitoring," according to Wu Guiying, a municipal lawmaker.

And Liu Yibing, political advisor and atomic energy researcher, said regulations and orders should be better implemented. He suggested that Beijing has not made the achievements it should have in tackling smog.

International cooperation has also been carried out with the aim of reducing pollution. In June, China and Finland signed a plan to promote advanced clean technologies. Endi