A study led by the Chinese University revealed that shifting to a less meat-intensive diet can mitigate air pollution in China by reducing agricultural ammonia emissions by about 20 percent.

The study analyzed the changing patterns of food production and consumption in China from 1980 to 2010.

Researchers found that rapid economic and population growth in China began in the 1980s, accompanied by a nationwide shift from a plant-based to a meat-intensive diet - culminating in China becoming the top meat-consuming nation in the world.

The average person in the mainland consumes 150 grams of meat per day while the average for Hong Kong is up to 200g per day, according to Amos Tai Pui-kuen, associate professor at the earth system science program who led the study.

Tai recommends people reduce their meat intake to between 40 and 75g per day -which is around the size of a person's palm - to tackle the pollution problem in China.

"The people of Hong Kong should reduce their meat intake by at least half," he said. Tai said people don't need to become vegetarians. However, he noted that "people must reduce excessive meat consumption."

The coauthor of the research paper published in Nature Food, professor Lam Hon-ming, said that people can turn to beans for protein instead.

The study also revealed that when people in China shift to a less meat-intensive diet, it can decrease particulate matter - a kind of air pollutant - by up to six micrograms per cubic meter and avoid 75,000 premature deaths related to air pollution annually, respiratory diseases ranking among the main drivers. It can also decrease agricultural ammonia emissions, which contribute to the formation of particulate matter, by some 20 percent.

Tai said that a more meat-intensive diet in China over the past 30 years has increased ammonia emissions from the agricultural sector by 63 percent.

Those in the poorer agricultural regions of China who consume less meat but produce most of it bear more of the health impacts of deteriorating air quality.

"[Higher meat consumption] has led to around 90,000 more air pollution-related premature deaths every year," Tai said.

The study is jointly conducted by CUHK, the University of Exeter and Peking University under the CUHK - University of Exeter Joint Centre for Environmental Sustainability and Resilience.