Bulletin Spring‧Summer 2001

exercise and climate change cause wheezing, etc. The questionnaire is recognize d internationally as a reliable tool fo r mea s u r i ng c h i l d h o od asthma,' Prof. Wo ng remarked. The research team then selected 1,000 participants f r om each of the three cities for a skin- p r i ck test to observe their response to different allergens. F i na l ly 200 c h i l d r en f r om eac h city were arranged to be given an a i r wa y sensitivity test. As the t wo tests were expensive a nd time- consuming, they could on ly be administere d on a smaller sample. The researchers also conducte d an en v i r onmen t al investigation i n to the homes of these children u s i ng standardized appraisal methods. They took samples of house dust f r om the bed, a nd the floors of the bed r oom, l i v i ng r o om , a nd kitchen, a nd measure d the concentration o f allergens u s i ng an i mm u n i ty test. Prof. Wong explained w h y no outdoor environmental data were gathered: 'International asthma research has shown that air quality ha s no effect on asthma. For example, Chongqing is mor e polluted than H o n g Kong, but the prevalence o f childhood asthma there is only a fifth of that i n H o ng Kong.' Hong Kong's Asthmatic Children Double Those in Beijing and Guangzhou The study f o u nd that the n umb e r of local asthmatic children i s double that of Beijin g a nd Guangzhou (Figure 1). Factors identified as 'high-risk' include home smoking , maternal smoking, use of synthetic p i l l ow a nd bedding, and use of gas as cooking fuel. ' A baby whose mother smokes du r i ng pregnancy w i l l have a narrower bronchial tube. If it continues to inhale second-hand smoke after birth, its bronchial tube w i l l n a r r ow even f u r t h e r , m a k i n g it p r o ne to i n f e c t i o ns a nd wheezing. Synthetic bedding an d p i l l ow contain o i l ingredients w h i c h s l ow ly releas e infection- c a u s i n g a n d d u s t - a t t r a c t i ng c h em i c al gas. C o o k i n g gas releases c a r b o n mo n o x i de a nd carbon dioxide, wh i ch trigger asthm a symptoms, because some of th e gases are not completely b u r n t i n the process,' Prof. Wo ng explained. The prevalenc e of asthma is f o u n d to be lower among children w h o were breast-fed (the longer the better), have siblings i n the h ome , a n d attend day care centres early on. Exposure to d i f f e r e n t viruses has been s h o w n to boost their i mmu ne system. Research conducted overseas hav e s h own house d u st a nd cats to be the mo s t c o mm on a l l e r gen s . O v e r 20 p er cent o f G u a n g z h ou children are f o u nd to be allergic to house dust, c ompa r ed t o o n ly 7 per cent for Beijing (Figure 2). G i v en the simila r prevalence of asthm a i n the t wo cities, one can conclude that w h i l e house dust is an allergen i n China , it is not as significant as i n the West. The s t u dy also f i n ds that children w h o are allergi c to dust a nd cats have a three to f our times greater chance of suffering f r om asthma t h an the n o r mal person. Prof. Wo ng p o i n t ed out, however, that this o n ly shows that these allergens ma y trigger an attack i n asthma-sufferers b u t not that they cause asthma. I n conclusion, Prof. Wo n g said, ' A s t hma patients are a hea vy b u r d en o n H o n g Ko n g ' s me d i c a l services. If t hey can l ea rn to a v o id certain r i sk factors i n the e n v i r o nme n t, w e can r e d u ce its p r e v a l e n c e mo r e e f f e c t i v e l y. We w i l l c o n t i n ue to e x am i ne t he l i n k b e t w e en en v i r onmen t a l factors a n d asthma so as to f i n d better preventive measures.' 30