A study carried out over 20 years in Galway has found a link between exposure to air pollution and childhood asthma.
The research - published in the latest edition of the Irish Medical Journal - looked at hospital admission rates for children between 1985 and 2005.
Researchers found that there was a strong connection between exposure to smoke and acute admissions.
These increased steadily, peaking in 1995, but they have diminished dramatically since then.
The report points out that in the ten years to 1995, there was an increase in the number of cars on the road with associated rise in air pollution.
Coal sales were steady during this time but there was a trend towards smokeless coal from the mid 1990s.
The authors suggest that regulatory changes regarding fuel sales and more stringent emission rules have improved air quality and reduced the incidence of hospital admissions.