University of Newcastle researchers have found that nearly one-third of Australian babies are regularly exposed to tobacco smoke in their home, increasing the child's risk of respiratory illness, asthma and Sudden Infant Death Syndrome.

Associate Professor John Wiggers and colleagues from the University of Newcastle found that up to 41 per cent of infants less than 12 months old lived with smokers and 27 per cent of those were exposed to tobacco smoke.

The findings have been published in the June issue of Australian and New Zealand Journal of Public Health.

The study shows infants are particularly vulnerable to the dangerous effects of passive smoking due to their small body size, higher ventilation rates and underdeveloped immune and pulmonary systems.

"It is important that people are aware of the risks they expose children to when they smoke around them," Associate Professor Wiggers said.

"The most effective way for parents to protect children is to stop smoking. This is good for the parents' own health as well."