China needs to draft laws to address worsening indoor air pollution, which deserves more attention, including targeted measures to better protect human health, experts said at a forum on June 14.

Soaring sales of air purifiers and talk of protective measures for people indoors have made headlines, along with severe outdoor air pollution, showing the public's growing concern about indoor air quality, they said.

"The controls on indoor air pollution are far from enough, compared with the national campaign against outdoor air pollution since 2013, and there is lack of scientific and systematic study of this issue, "Hou Li'an, an academician at the Chinese Academy of Engineering, said at the forum in Beijing on indoor air quality.

It's urgent to draft laws, considering it will take years to see air quality reach consistently good levels in Chinese cities, even though great reductions of airborne pollutants such as PM2.5 particulate matter have been achieved, he said.

PM2.5 refers to particulate matter with diameter of 2.5 microns or less that is hazardous to human health. Its concentration is a major index for measuring air quality.

Indoor air quality has been greatly influenced by air quality outside. On smoggy days, indoor air is also polluted, Hou's research showed. That opinion is shared both at home and abroad.

According to the World Health Organization, 4.3 million people a year die from exposure to indoor air pollutants worldwide.

In addition to pollutants from outside, the WHO says, indoor air quality sources include cooking and heating, which can produce some health-damaging pollutants, including PM2.5.

Moreover, if someone smokes in an enclosed room on a smoggy day, the air pollution indoors may be more severe than the outside level, and thus more harmful to people, Mao Qun'an, a publicity official from the National Health and Family Planning Commission, said in a news release in January after many days of heavy pollution.

PM2.5 concentration indoors should be less than 75 micrograms per cubic meter for elderly people and children - the cutoff line for what is defined as "good" air outdoors, the news release quoted Wang Yu, head of the Chinese Center for Disease Control and Prevention, as saying.

But indoor air quality standards that took effect in 2002 have not been updated in recent years, according to Hou.

"We have urged the authorities to update them to keep up with recent air pollution levels," he said.

Unlike outdoor air pollution, which falls under the authority of the Ministry of Environmental Protection, indoor pollution falls under the National Health and Family Planning Commission.

There should be regulations to control the domestic air purifier market, which is promising but chaotic, so that machines meet the same strict standard, and better protect health, Hou added.

Xin Wen contributed to this story.

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(China Daily European Weekly 06/16/2017 page14)