Editor's note

The heavy smog and haze that shrouded Beijing on the weekend — pushing the pollution index to a record high — has been dubbed the "Beijing Cough" by the city's expat community, becoming increasingly popular with local media and Chinese.

Meanwhile, many other cities also witnessed smoggy weather on the weekend. On Saturday, levels of PM2.5 passed 300 micrograms per cubic meter in 33 of the 74 cities with systems equipped to monitor the particles. Face mask sales surged and hospitals crowded with sick people in cities across the country. 

What's PM2.5?

Particles 2.5 microns or less in diameter (PM2.5) are referred to as "fine" particles and are believed to pose greater health risks than larger particles because they can embed deep in people's lungs. 

PM2.5: Easy to monitor but hard to control

Sources of PM2.5

The growth and severity of PM2.5 pollution in recent years is directly related to the rapid rise in coal consumption, allied to an increase in vehicle exhaust emissions. Although some cities are leading the way in the reduction of coal use in absolute terms, their neighbouring cities share each other's polluted air. >>

Modern toxicology research has shown that exposure to PM2.5 can lead to significantly increased death rates due to cardiovascular, cerebrovascular and respiratory diseases, as well as increased cancer risk.

PM2.5 kills thousands: researchers

Heavy fog envelops China

Smoggy weather engulfs large areas of China

Heavy fog enveloped a large swathe of East and Central China on Saturday, causing highway closures and flight delays in several provinces.

Beijing was shrouded in dense smog for a second straight day on Saturday. Meanwhile, heavy fog has blanketed other regions including Hebei, Tianjin, Shandong, Henan, Jiangsu, Anhui, Jiangxi and Hubei. >>

Beijing's air pollution reached dangerous levels yet again on Jan 13, marking the third consecutive day of severe smog,municipal environmental authorities said.

The municipal meteorological station issued the city's first orange fog warning Sunday morning due to decreased visibility caused by the heavy smog. >>

Healthy debate over Beijing's air quality 

PM2.5 is easily inhalable and canpenetrate deep into the lungs. PM2.5 allows many chemicals harmful to human health to be carried to the internal organs, causing a wide range of illnesses, including cancer (especially lung cancer), stroke and damage to unborn children. They have a strong association with most types of respiratory illnesses, heart disease and even deaths. >>

Advices for public 

Face masks

N95 filter respirators, a type of mask designed to combat PM2.5 and intended for those with no alternative to going outdoors.

"They definitely stop PM2.5. The definition of N95 literally means it filters 95 percent of particulate matter — as small as PM0.3 microns, much smaller than PM2.5."

Avoid going outside

Warnings have been released to the public through channels such as micro blogs, television and radio, urging people to reduce the amount of time they spend out of doors and to increase their use of public transport.

Schools are being advised to arrange fewer outdoor activities for the kids.

China pledges $56 billion to cut air pollution

China will spend 350 billion yuan ($56 billion) by 2015 to curb air pollution in major cities.

Local governments will fund most of the programmes aimed at cutting the level of harmful particles in the air in 117 cities by at least 5 percent between 2011 and 2015, the Ministry of Environmental Protection said in a statement on its website. >>

74 Chinese cities release real-time PM2.5 data 

Starting Tuesday, real-time air quality monitoring data on PM2.5 intensity in China's 74 major cities is available at the website of www.cnemc.cn.

The move is considered a big improvement in air quality monitoring, made at the strong request of the public. >>

Public backs ministry's air quality plans

Heavily polluted Lanzhou city to publish PM2.5 data

Beijing to tighten car emission regulations

The Chinese capital is likely to adopt new vehicle emission permits which could be as strict as those in Europe, in response to concerns over the city's air pollution.

The Beijing Municipal Environmental Protection Bureau has released a draft of new standard which specifies strict limits for a variety of vehicle emissions, including carbon monoxide, hydrocarbons, nitric oxide and particulate matter. >>

Beijing parks govt cars to improve air quality

Beijing will take some government cars off its roads as part of a campaign to lower the city's PM2.5 readings and improve air quality, according to an air pollution abatement plan made by the municipal government. >>

Air pollution top priority in Beijing

Pollution masks given to outdoor workers

Among the factors affecting PM2.5, we can't control meteorological factors. What we can do is just drive less and live a green life. While more people seek to live a green life by reducing pollution, we can look forward to better quality air, a cleaner environment and improved health.