The warning — in reference to a U.S. embassy Twitter account that, since 2008, has posted hourly readings of pollution levels of Beijing — illustrated how sensitive the government is about the country’s pollution problem.
And it's a problem that is becoming a growing concern among the public and considered a leading cause of civil unrest. The planned construction of industrial plants has sparked protests in some cities. Bowing to public pressure, officials shut down a planned copper plant for a southwestern China city on Wednesday after thousands protested the possible health impact from the facility.
But is China's pollution really that bad?
According to the Environmental Performance Index, a bi-annual report put out by Yale University and Columbia University that ranks countries based on a number of environmental factors, India ranked last out of 132 countries.
Yet, China wasn't far off, coming in at 128. Its overall index rank, which, along with air quality, included factors such as water, agriculture, and climate change was 116. (India came in at 125).
Leads in emissions
But China is still considered one of the biggest polluters in the world and leads in a number of categories including CO2, sulphur dioxide and mercury and arsenic emissions.
China’s pollution comes mostly from its coal-fired power plants and motor vehicle emissions which emit large quantities of particulate matter and sulfur dioxide.
Part of the reason the Chinese government is so irked at the U.S. reporting pollution data is that their pollution standards are more stringent which means pollution levels considered unhealthy in the U.S. are often classified as good by China.
"Air pollution in China is notorious for its magnitude," wrote researchers at the MIT Joint Program on the Science and Policy of Global Change in one study looking at the effects of the country's pollution on GDP.
In 1980, levels of particulate matter in China were at least 10 to 16 times higher than the World Health Organization’s annual guideline value, according to the authors. In 2005, as air quality had substantially improved, the levels were still around five times higher.
Soil contamination concerns
China also has problems with soil contamination from arsenic and other heavy metals from mines and factories. Zhou Jianmin, director of the China Soil Association, told the Guardian last month that he estimated that one-tenth of China’s farmland was affected. Soil contamination could have potentially dire consequences for food production and human health, scientists told the Guardian.
"The country, the government and the public should realize how serious the soil pollution is,” Jianmin said. “More areas are being affected, the degree of contamination is intensifying and the range of toxins is increasing."
Water pollution is also a growing challenge. China's own government has admitted that about 14 per cent of China's water sources had unqualified drinking water and that 11.4 per cent of water supplies to cities were unsafe.
Government statistics from 2009 reveal that nearly 20 per cent of the length of China's monitored rivers and lakes had pollution worse than Grade 5, making the water officially unfit for even irrigating crops, Reuters reported.
The concern now is that the health impact from pollution is chipping away at the economic gains made due to industrialization.
The MIT study noted that three decades of unprecedented growth in China has given rise to "important quality of life improvements for the more than half a billion people who have been raised out of poverty." But this has come with a price.
"China now faces severe challenges relating to its environment, including air pollution, the availability of clean water, and desertiﬁcation, the report said.
"Issues such as these have the potential to create constraints on future growth. Those environmental problems that result in negative health outcomes, such as contaminated water and high levels of air pollution, also incur real costs on the individuals, the health system, and the economy as a whole."
GDP affected by pollution
A World Bank study estimated that damage to human health from air pollution in China was around 4 per cent to 5 per cent of GDP levels between 1995 and 2003. But the MIT study estimated the damage at around 6 per cent to 9 per cent of GDP.
In fact, the study estimated that lost labour and health care costs associated with pollution cost the Chinese economy $112 billion in 2005.
The OECD recently released a report estimating that the number of premature deaths from exposure to particulate matter is projected to more than double worldwide to nearly 3.6 million per year in 2050, with most deaths occurring in China and India.
Some Chinese officials have been surprisingly frank in expressing their concerns.
In delivering the "state of the environment" report last year, Li Ganjie, China's vice minister of environmental protection, admitted that "the overall environmental situation is still very grave and is facing many difficulties and challenges."
Li said while pollutants in surface water and sulfur dioxide emissions in cities were down, the countryside was becoming more polluted, pledged to control contamination by heavy metals and that China needed a law to regulate heavy metals, the New York Time reported.
Environmental observers say there are other promising signs of China's commitment to tackle pollution. Earlier this year, officials said Beijing would start reporting air quality data that includes readings of particulate matter that measures 2.5 microns or less in diameter.
This was seen as an important step, as it's this size of particle that can enter someone's lungs or bloodstream, causing health complications.
Nicholas Lardy, a leading expert on China's economy, told CBC News that while China has reduced the energy use per unit of GDP quite substantially, GDP is still growing rapidly, meaning the total amount of pollutants is still going up in absolute terms. For example, China continues to burn up around four billion tonnes of coal a year.
"The good news is that compared to business as usual they've made substantial progress. The bad news is they are still the largest emitter of most of the bad stuff," he said.