China's Ministry of Environmental Protection on Monday called for local officials to increase their efforts to issue early warnings for air quality.

The ministry's directive Monday, reported by Xinhua news service, follows record levels of hazardous air pollution in Beijing and many parts of the country in which visibility in some locations was as low as 328 feet.

Since 2008 the U.S. Embassy in Beijing has made public the city's air quality readings based on measurements of PM2.5 -- air pollution particles less than 2.5 micrometers in diameter - which pose health risks.

Those readings reached 886 micrograms per cubic meter on Saturday, a level 35 times the World Health Organization's recommended standard for air quality.

On Sunday, Beijing for the first time issued an "orange" fog warning for the elderly, children and people suffering from respiratory disease to stay indoors.

Xinhua reported a sharp rise in people seeking treatment at Beijing hospitals for respiratory problems.

Ahead of the 2008 Olympics, Beijing was able to boost its air quality by improving vehicle emissions standards, banning coal stoves and shifting heavy industry to poorer areas of the country.

But since then, there has been a huge increase in the numbers of cars on the roads and China, the world's top emitter of greenhouse gases, continues to rely on coal to generate electricity and for industrial uses such as steel-making.

"Because of the challenges, this isn't going away in a day, one year or one decade," Xu Yuan, who researches air-pollution mitigation strategies at the Chinese University of Hong Kong, was quoted as saying by The Wall Street Journal.

As part of its five-year plan that ends in 2015, China aims to reduce the amount of carbon emitted per unit of gross domestic product by 17 percent by 2015, compared with 2010 levels.

"China's national leaders have ordered an improvement in air quality but thanks to misreporting and manipulation of data" by lower-level officials, senior officials often aren't aware of the severity of the problem, says Steven Andrews, an environmental consultant who exposed official manipulation of air pollution data in Beijing in the run-up to the 2008 Olympics, the Financial Times reports.

Chinese scientists who have conducted independent studies on air quality have said techniques often are used to come up with readings that show improvements, ranging from changing the readings to placing city air monitoring stations in locations where pollution levels are lowest, such as in parks or close to sprinkler systems, says the Times report.