BEIJING: Public anger in China at dangerous levels of air pollution, which blanketed Beijing in acrid smog, spread on Monday as state media editorials queried official transparency and the nation’s breakneck development.

State media joined Internet users in calling for a reevaluation of China’s modernization process, which has seen rapid urbanization 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 meters in some areas and forcing flight cancellations. Reports said dozens of building sites and a car factory in the capital halted work as an anti-pollution measure.

Beijing authorities said readings for PM2.5—particles small enough to deeply penetrate the lungs—hit 993 micrograms per cubic meter at the height of the pollution, almost 40 times the World Health Organization’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.

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 environ-mental 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 criticized for initially denying the existence of the Severe Acute Respiratory Syndrome (SARS) outbreak in 2003.

The Global Times also 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 industrialization, but observers say the increasing availability of the statistics has forced them to confront the issue more directly.

An editorial in the China Daily blamed the pollution on the pace of urbanization, adding that “China’s process of industrialization has not finished.”

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.

“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.