Currently fewer Canadian children are being diagnosed with asthma, due to reduced number of smokers and consequently because of reduced exposure to second hand smoke, according to statistics.

In more than a decade rates of the chronic inflammatory disease dropped to substantially reduced levels among children aged two to seven.

"A variety of environmental factors, as for example reduced exposure to cigarette smoke contributed significantly to these statistics," the study declares.

Canada's national statistical agency (Statscan) showed that 9.8% of children aged two to seven were diagnosed with asthma in 2008-09, significantly lower than 13.2 % in 2000-01.

This drop occurred mainly because fewer Canadian children live in families where adults smoke, according to study.

About 6% of children aged 11 and under were regularly exposed to second hand smoke at their homes in 2008, if compared with 24% in 2000. As about teenagers 13% aged 15 and older smoked regularly in 2008, dropping from 19% in 2000.

In present a few parents smoke because there were no statistically proved differences in asthma rates between children in smoking and non-smoking families between 2006-07 and 2008-09.

"This data shows that adult smoking rates dropped significantly, thus parental smoking is not seen as the leading cause of asthma in young children," declared the representative of Statscan.

This link between reduced smoking and fewer cases of asthma are not unique only for Canada. For example, after Scotland prohibited smoking in public places, serious cases of asthma fell among preschool and school-aged children.

For instance researches from western countries discovered that asthma rates among children rose steadily for several decades before decreasing.

Statscan declared that reduced disease rates might also be due to changes in the population structure, changes in diagnostic methods, decline in the predominance of respiratory allergies, advances in air quality and changes in hygiene practices.

As well as asthma, ear infections are related to exposure to second hand smoke.

Canada’s national statistical agency found out that asthma predominance decreased in the Atlantic Provinces, Ontario and Quebec, but remained quite stable in the West. This survey also discovered that the number of children who had had an asthma attack in the past 12 months dropped to 36 % in 2008-09 from 53 % in 1994-95.

The give study is based on data presented by the National Longitudinal Survey of Children and Youth, a long-term study that capture information from thousands of families. The survey has been led every two years since 1994-95.