AUGUSTA – Maine has the highest rate of childhood asthma in New England, according to a new report.

A study by the Boston-based New England Asthma Regional Council says 13.2 percent of Maine’s children have been diagnosed with asthma during childhood. That compares with 12.3 percent for the region as a whole.

The study says 9.3 percent of Mainers under 18, or 28,100 children, are currently diagnosed with asthma. For all of New England, 8.3 percent of the children now have asthma.

Health officials were not surprised by the state’s ranking, but were startled by the extent of the problem.

“What did surprise us is how big the number is,” said Ed Miller of the American Lung Association of Maine. “It’s distressing. I think the problem has been getting worse rather than better.”

Asthma is one of the most common diseases in the United States, with an estimated 15 million cases nationwide. It is characterized by inflammation of the airways that causes wheezing, coughing and difficulty in breathing.

Betsy Rosenfeld, chairwoman of the council’s executive committee, said a nationwide study showed a 75 percent increase in childhood asthma between 1980 and 1994. The rise led officials to look into rates in New England’s six states.

“We had a sense from national numbers that childhood asthma is reaching epidemic proportions,” said Rosenfeld, who is a health administrator for the U.S. Department of Health and Human Services. “But when you see that number in black and white, it’s pretty significant.”

The study was compiled using telephone surveys of more than 10,000 families. Rosenfeld said the study is the first of its kind and is the most comprehensive look ever at childhood asthma.

The causes of asthma are unknown, but the survey said several factors – including air pollution, mold and mildew, and cigarette smoke – seem to contribute to childhood asthma.

Dr. Dora Anne Mills, director of the state Bureau of Health, said some of the contributing factors in Maine may be older-than-average housing that is prone to mold, high poverty rates and a harsh climate that can force children indoors. Maine has the highest poverty rate in New England.

Mills said pollution that streams into Maine from Midwestern power plants adds to the problem.

The report also said asthma rates among children were highest in households with low income levels. Maine has the lowest income levels in New England.

“We have a long way to go,” Mills said. “Asthma absolutely is going to need to be a top priority.”

The report says that asthma is one of the leading causes of school absence, emergency room visits and hospitalizations.