A report from the Australian Institute of Health and Welfare released yesterday has warned the respiratory illness would continue to rank as one of the major causes of disease burden in Australia for the next 20 years.

"This burden is particularly heavy for children asthma is the leading cause of burden of disease among children, ahead of anxiety and depression," Professor Guy Marks, of the Australian Institute of Health and Welfare's Australian Centre for Asthma Monitoring, said.

In the Hunter and New England, asthma is the most common cause behind hospital admission for children under the age of six, while about one in six youngsters across the region are predicted to develop an asthma-related illness.

Hunter New England Health staff specialist Peter Wark said it was unclear if the high rates were due to environmental or genetic factors.

"It's difficult to know why we are seeing more of the disease," he said.

"It's hard to gather the statistics that would make that clear."

Dr Wark said children were not the only ones at risk.

A NSW Population Health Survey showed 13 per cent of people aged 16 and over in the region had asthma in 2007, compared with 10.5 per cent statewide.

People aged between 25 and 34 had the biggest representation, with more than 19 per cent diagnosed with the disease, compared with a state average of 10.5 per cent.