Damp, moldy buildings can make asthma worse and cause coughing, wheezing and other breathing problems in healthy people, but there is no good evidence that they can cause other illnesses, the National Academy of Sciences concluded yesterday.

Nevertheless, given how commonly moisture problems occur in homes and other buildings, people should remove any mold they find as soon as possible, and more research should be done to investigate possible links to health problems and ways to build drier structures, the academy said.

"Because excessive dampness is prevalent in buildings and is associated with a range of respiratory symptoms, it constitutes a public health problem," said Noreen Clark, dean of the University of Michigan School of Public Health. She led a nine-member expert committee that reviewed the issue for the academy's Institute of Medicine (IOM).

"Even though the available evidence does not link mold or other factors associated with building moisture to all the serious health problems that some attribute to them, excessive indoor dampness is a widespread problem that warrants action," she said as the committee released a report on the issue.

As buildings have become more tightly sealed to make them more energy efficient, concern has been increasing that trapped moisture can promote the growth of mold, bacteria, dust mites and other organisms that could be causing widespread allergic reactions and other health problems, including stomach problems, fatigue and even possibly neuropsychiatric problems, cancer and reproductive difficulties. The concern has resulted in a rash of lawsuits and insurance claims over the issue.

In response, the federal Centers for Disease Control and Prevention in Atlanta asked the IOM to investigate. The IOM formed the expert panel, which conducted the comprehensive review of the scientific literature on the issue and wrote the new report.

It concluded that the only good evidence showed that mold can exacerbate asthma and cause coughing, wheezing and other upper-respiratory symptoms in otherwise healthy people.

"These findings are supported by a large number of studies that consistently show an increase in the prevalence of these health effects among occupants of buildings that have dampness problems or visible mold," Clark said.

There is also suggestive evidence that dampness might be associated with developing asthma, and limited evidence for a link with shortness of breath and lower-respiratory problems in children.

"What little scientific data there is on links between indoor dampness and other health problems, such as fatigue and difficulty in concentrating, does not support an association," Clark said. "However, because of the dearth of well-conducted studies and reliable data, the committee could not rule out the possibility that such a link might exist."

Because dampness is a widespread problem, and so much scientific uncertainty exists, the committee called for better building design, construction and maintenance to minimize such problems.