Fumes let off during cooking at home can be linked with respiratory issues, including cancer, but more research needs to be done to determine the effect on air pollution levels, according to medical and cooking experts.

"It is certain that fumes from cooking, especially frying, can cause irritation to the respiratory tract and may be a partial cause of cancer among some people," said Chen Jingyu, a lung surgeon and vice-president of Wuxi People's Hospital in Jiangsu province.

"But so far, no scientific research has been done to identify cooking fumes as a cause of high PM2.5 levels," he said.