NEW HAVEN, Conn. (WTNH) — Spring may be a welcome season for many, but for children with asthma, the pollen that comes with it can mean difficulty breathing. It is something Yale researchers are studying as they look to improve air quality.

“New Haven, Bridgeport and Hartford were all in the top 10 cities nationwide for high asthma prevalence in children in a recent survey,” said Dr. Sten Vermund, dean of the Yale School of Public Health.

Vermund said asthma is a chronic lung disease that makes it hard to move air in and out of the lungs. He said children have smaller airways to begin with, making them more susceptible to environmental triggers such as pollen, car exhaust and cigarette smoke. That pollen is a problem this time of year.

“You may do some trimming of some flowers and plants in your yard and even selecting plants that are not as intense with pollens,” Vermund said.

He said you can improve air quality in a home by eliminating mold, using quality filters in heating and air conditioning systems and using portable air filtration.

Childhood asthma is a major problem. It is the third most common cause for children’s hospitalizations.

WEB EXTRA: Dr. Sten Vermund, dean of the Yale School of Public Health, discusses childhood asthma and what parents can do to help their children breathe a little easier

Connecticut lawmakers are considering a major clear air bill this year intended to help lower urban asthma rates.

“It’s especially a concern in disadvantaged and underserved communities that tend to be closer to major transport corridors and industrial centers.”

A Yale global health asthma working group studied this.

“We found alarming rates of asthma in especially lower income neighborhoods in New Haven,” Vermund said.

They found that kids in New Haven were five times more likely to be hospitalized from asthma. He explained there are effective medical treatments for asthma available and there are even plants, shrubs and flowers that carry less pollen.

Asthma not only has physical dangers that interfere with breathing, but it also takes a toll on a child’s abilities to take part in school and other normal activities. Now that more children are becoming overweight, doctors are seeing more cases of asthma.