Classroom pollution tests cause alarm Air pollution inside Hong Kong's schools can reach levels almost as high as those outdoors on high pollution days, checks in schools have shown. The Sunday Morning Post accompanied an allergy management expert to four schools on Monday, when the government's general air pollution index (API) was high, and found indoor levels of respirable suspended particulates (RSPs) in three of the schools ranged between 76 per cent and 98 per cent of outdoor levels. A check on the same schools five days earlier, when the API was medium, found far lower indoor levels of the lung-damaging particles. The government's outdoor air quality objective for RSPs is 180 micrograms per cubic metre. At an API of 200 - the threshold beyond which it advises sporting events be cancelled - the level of RSPs is 350. The calculation of RSP levels by Teddy Sung Siu-hung, who took the measurements at the schools using hand-held equipment, differs from the government's; still, he called the readings alarmingly high. The findings pose a fresh challenge for principals considering whether to cancel events when the air pollution index is very high. Chinese International School moved its annual swimming gala at Victoria Park indoors when the roadside air pollution index reached 111 last month. Health experts say the indoor pollution levels registered on Monday would be harmful to health and unsuitable for indoor exercise, and are calling for systematic, localised monitoring around schools. Mr Sung's allergy-control equipment firm, Allercure, took outdoor and indoor readings for particulates at schools in Mong Kok, Lam Tin, Aberdeen and on The Peak using a particle scanner. Conditions on Monday were smoggy, while the previous Wednesday was breezy. The outdoor readings on Monday were 437 at Canadian International School in Aberdeen and 352 at Wah Yan College in Mong Kok. The reading five days earlier at both was 81.9. At SKH Kei Hau Secondary School in Lam Tin, the outdoor level on Monday was 341; at German Swiss International School on The Peak it was 303. Indoor readings were almost as high, reaching 345 at Wah Yan, 286 at German Swiss and 259 at Kei Hau. They were much closer to the outdoor readings than those taken when pollution was lower. Only Canadian International, which has no outdoor corridors between classrooms, had a significantly lower indoor reading, at 124. Anthony Hedley, professor of community medicine at the University of Hong Kong, said: 'These figures are very disturbing. They indicate the indoor environment does not offer meaningful protection.' Alfred Tam Yat-cheung, vice- chairman of the Hong Kong Asthma Society, called the findings very significant. 'I think we need to have more measurements at schools across Hong Kong,' he said. Dave McMaster, principal of Canadian International, said the readings showed particulate pollution could be just as bad on the south side of Hong Kong Island as in the heart of the city. Norman So, principal of Wah Yan College, said: 'We shall try to explore ways to improve air quality.' A spokeswoman for the Environmental Protection Department said portable monitoring devices did not measure air quality accurately. Mr Sung said the hand-held scanner measured the concentration of particulates and converted this to particle mass based on an equation from a US-based company that was a major retailer of air monitoring and purifying equipment. The results were then verified using readings from an aerosol monitor recognised in the government's indoor air-quality certification scheme.