San Francisco can improve asthma rates and ease symptoms in children who already have the chronic disease by cleaning up public housing units and reducing allergens in schools, according to a report released Tuesday by the San Francisco Asthma Task Force.

The report noted wide disparities in the severity of asthma among San Francisco neighborhoods, with children in poor areas up to seven times more likely than children in other parts of the city to end up in the emergency room or hospitalized with an asthma attack.

In 2005, more than 26 percent of children ages 5 to 17 had asthma in San Francisco, according to the California Health Interview Survey.

In the Bay Area at large, 19.8 percent of children had asthma in 2005.

There is no cure for asthma, but various treatments are available, and symptoms can improve if care is taken to remove allergens from the home or other environments where children regularly spend time.

Allergens can include cigarette smoke, rodents and insects, and ingredients in cleaning products.

With that in mind, the Asthma Task Force recommends, among other things, that San Francisco amend building codes to improve healthy housing requirements; create incentives for private property owners to improve air quality in rental units; and buy allergen-free cleaning products for use in public schools.

E-mail Erin Allday at eallday@sfchronicle.com.