Hong Kong indoor air pollution so bad it could be making you chronically ill, tests show
Pollutant levels up to 1,250 per cent higher indoors than outdoors, and PM2.5 fine-particle pollution worse than beside some of the city’s busiest roads, shock research by Baptist University finds
The air pollution inside some Hong Kong homes is worse than beside some of the city’s busiest roads, tests show. And it could be making the homes’ occupants chronically ill, worried scientists say.
Levels of small-particle pollution, known as PM2.5, that can lodge deep in people’s lungs were on average nearly 10 per cent higher indoors than the highest level found outdoors.
Levels of volatile organic compounds (VOCs) - carbon-based chemicals that easily evaporate at room temperature - were, on average, over 1,250 per cent higher in kitchens than outdoors. And the median level of VOCs in 27 of 32 homes tested exceeded the recommended maximum level for Hong Kong offices.
One of the researchers said indoor air pollution - from perfumes, cleaning products and cooking fumes - turned the average Hong Kong home into a “mini chemical warehouse”.
Studies in other countries have also found indoor air pollution is higher than that outdoors. The situation in Hong Kong could be aggravated by factors such as high-rise living, subdivided flats, a lack of windows and ventilation in some rooms, and restaurants occupying ground-floor premises in residential buildings, one of the researchers said.
The research was conducted by Baptist University’s biology department and household appliances manufacturer Dyson. Air quality was tested in 32 homes, with samples taken in their living rooms and kitchens, and directly outside these rooms.
“VOCs are consistently higher indoors than outdoors. Even so, the research found that the kitchen VOCs are on average 1,258 per cent higher than outdoors,” said Baptist University’s Dr Lai Ka-man, who led the research in March.
The researchers’ report, citing the US US Environmental Protection Agency, says: “Toxic fumes released from cleaning solvents, deodorants and scented candles are some of the most common indoor air pollutants. Other major indoor air pollutants include gases from cooking, mould, pet hair, pollen and allergens.”
Readings were also taken at seven outdoor locations around the city.
The tests found micro-particle pollution, or PM0.1, was on average 68.5 per cent higher inside homes than outside. (PM0.1 is one-thousandth the diameter of a human hair, and can penetrate the lungs and enter the bloodstream.)
Hong Kong has no guidelines on recommended levels of indoor particulate matter, but it is indicative that outdoor readings in busy roadside areas often reach dangerous levels on the air pollution index – levels that, ironically, trigger warnings to residents with respiratory problems to stay in their homes.
Surprisingly, Lai said, indoor levels of PM2.5 were higher than outdoors. Indoor readings were on average 9 per cent higher than the highest reading recorded outdoors, of 369 ppl, outside Sogo in Causeway Bay; the PM2.5 reading in Nathan Road, Mong Kok, one of the city’s busiest urban roads, was 363ppl.