(Beijing) – The effects of bad air from the heavy clouds of pollution over many Chinese cities are becoming vividly clear, according to a recent study.

Air pollution was linked to at least 8,572 premature deaths across four major cities in 2012, in a study by Peking University and Greenpeace published December 18. The study also said smog in Chinese cities caused a total of 6.8 billion yuan in economic losses.

"The premature deaths in the report refers to excessive mortality – that is the calculation of mortality under the effects of certain factors; not premature death in the statistical sense which signifies a death prior to reaching average life expectancy," said Pan Xiaochuan, professor from Peking University's School of Public Health.

The report is based on PM2.5 monitoring data and the number of deaths related to respiratory and cardiovascular diseases collected in Beijing, Shanghai, Guangzhou and Xi'an.

PM2.5 refers to fine particulate matter. With an aerodynamic diameter less than 2.5 micrometers, these fine particles lodge in the lungs and are absorbed into the heart, blood and lung vessels. This can lead to heart, brain and lung disease, including cancer.

Cities in the Yangtze River Delta, Pearl River Delta and the Beijing-Tianjin-Hebei region suffered over 100 hazy days every year with PM2.5 concentrations two to four times above the World Health Organization guidelines, said the report which cited figures from the Ministry of Environmental Protection.

"PM2.5 is putting public health at high risk every day, but worse still, if we follow the current official plans we would need to wait 20 years to get to the national standard," said Greenpeace climate and energy campaigner Zhou Rong.

China has seen numerous studies on air quality in the past. In 2007, a joint study by China's State Environmental Protection Administration, the former incarnation of the Ministry of Environment, and the World Bank estimated that each year between 350,000 to 400,000 deaths are attributable to air pollution.

"The topic was regarded as too sensitive by China's environmental protection authorities, so the report was never publicized," Pan said.

After decades of maintaining a see-no-evil stance towards polluters and heavily criticizing the U.S. embassy in Beijing for publishing daily measurements which contradicted official assurances, the publication of the most recent report has been viewed as a step forward in official openness. Previously, official statements linked poor air quality to fog or dust from Mongolia.

Greenpeace urged authorities to launch a major initiative to retro-fit existing coal-fired power plants with nitrogen oxide scrubbers, to shut down inefficient coal-fired industrial boilers and cap regional coal consumption as much as possible.

On December 30, state media announced that the Ministry of Environmental Protection would begin to release air pollution data for 74 of China's largest cities.