So called "anti-smog" tea is unreliable and may even cause additional health risks, an expert in traditional Chinese medicine (TCM) told China Central Television.

Liu Quanqing, president of the Beijing Hospital of Traditional Chinese Medicine, warned consumers against such teas, which are being promoted by some vendors as a way to clean the lungs amid the heavy smog that persists in parts of China.

What we eat or drink is digested and absorbed in our digestive system, while the PM2.5 particles enter our respiratory system through nose. The two systems are independent, Liu said.

"I've looked at many formulas. They all contain ingredients that are medicines and can't be used as food, which may cause health problems if taken for a long time," the expert said.

Liu added that other suggested remedies for cleaning the lungs, such as eating kelp, radish or wood-ear fungus, were also not genuine. "The lungs have a natural cleaning system. For example, we cough to help the lungs flush out impurities," he said.

From a TCM perspective, adjusting one's mood or eating habits could be more helpful in strengthening the immune system, Liu said.

In the past few days, as Beijing has been continuously shrouded in heavy smog, Liu's hospital has not seen a rise in the number of patients with actual respiratory problems. However, many patients have come in with mental health problems and fears related to the increase in smog, with many concerned about developing asthma, for example.

Liu advises the public to develop good eating habits, enhance their immune systems and try to relax mentally to better cope with smoggy days.