1. March 1992 Accepted 16 June 1992
2. An increase in the prevalence of asthma among young Finnish men has been reported to Phelan PD. Prevalence of asthma in Melbourne schoolchildren: changes over 26 years;Robertson, C.F.; Heycock, E.; Bishop, J.; Nolan, T.; Olinsky, A.;BMJ,1991
3. Asthma in Danish general prachave taken place since the early 1960s.' The use tice;Pedersen, P.A.; Weeke, E.R.;Allergy,1981
4. Prevalence of asthma and hay fever in England and Wales;Fleming, D.M.; Crombie, D.L.;BMJ,1987
5. Increased rates of illness and death from asthma mortality from asthma in Finland, and the in Canada;Mao, Y.; Semenciw, R.; Morrison, H.; MacWilliam, L.; Davies, J.; Wigle, D.;Can Med Assoc J; number of asthma related deaths has decreased,1987