Public anger in China at dangerous levels of air pollution, which has blanketed Beijing in acrid smog, has spread as state media editorials questioned official transparency and the nation's robust development.
State media on Monday joined internet users in calling for a re-evaluation of China's modernisation process, which has seen rapid urbanisation and economic development achieved at the expense of the environment.
Dense smog shrouded large swathes of northern China at the weekend, cutting visibility to 100 metres in some areas and forcing flight cancellations. Reports said dozens of building sites and a car factory in the capital halted work as anti-pollution measures.
Beijing authorities said readings for PM2.5 - particles small enough to deeply penetrate the lungs - hit 993 micrograms per cubic metre at the height of the pollution, almost 40 times the World Health Organisation's safe limit.
Experts quoted by state media blamed low winds for the phenomenon, saying fog had mixed with pollutants from vehicles and factories and been trapped by mountains north and west of Beijing. Coal burning in winter was also a factor, they added.
Call for transparency
In an editorial on Monday the state-run Global Times newspaper called for more transparent figures on pollution, urging Beijing to change its "previous method of covering up the problems and instead publish the facts".
Officials in China have a long history of covering up environmental and other problems by not releasing information.
Earlier this month a chemical spill into a river was only publicly disclosed five days after it happened, and the authorities were widely criticised for initially denying the existence of the Severe Acute Respiratory Syndrome (SARS) outbreak in 2003.
"The choice between development and environmental protection should be made by genuinely democratic methods," the Global Times said. "Environmental problems shouldn't be mixed together with political problems."
The paper ran a story on differences between air quality figures given by Chinese authorities and the US embassy in Beijing.
Official PM2.5 figures have only been released for China's biggest conurbations since the beginning of last year, and expanded to cover 74 cities earlier this month.
China's tightly-controlled media have previously raised concerns over health problems linked to industrialisation, but observers say the increasing availability of the statistics has forced them to confront the issue more
An editorial in the China Daily blamed the pollution on the pace of urbanisation, adding that "China's process of industrialisation has not finished".
"In the middle of a rapid urbanisation process, it is urgent for China to think about how such a process can press forward without compromising the quality of urban life with an increasingly worse living environment," it said.
The paper also called on Beijing's five million car owners and government officials who use state-owned cars to rethink their driving habits and urged the government to tackle industrial pollution.
Meanwhile, share prices of environment-related companies surged.
Face mask producer Shanghai Dragon Corp soared by its 10 percent daily limit shortly after the Shanghai market opened, while air purification equipment maker Create Technology & Science rose 7.80 percent.
"The widespread smoggy weather has led to the increase in respiratory patients, so there are investment opportunities in stocks related to air purification equipment and anti-bacterial masks," said Sui Guoming, an analyst at Kaimenhong Investment Management company, on his microblog.
Smog levels eased in the capital on Monday, with the monitoring centre putting the PM2.5 reading at 400 in central Beijing, but the crisis still dominated discussion on Sina Weibo, China's hugely popular version of Twitter.
"This pollution is making me so angry," said one web user, who also posted a picture of herself wearing a face mask.