Mold exposure may worsen asthma for middle-aged adults

Mold exposure in the home raises the risk of asthma symptoms in middle age, according to a new study from Australia.

The more mold participants reported having seen in their homes, the greater their asthma symptoms, researchers found. Men were especially vulnerable with a four-fold increase in the odds of having non-allergic asthma after recent exposure to visible mold.

"The mold exposure that we were talking about is the typical mold that we all see in our homes from time to time, that is, mold that you see in the wet areas of the house, e.g., bathroom, kitchen and laundry," John Burgess told Reuters Health in an email.

Burgess, a researcher with the Melbourne School of Population and Global Health at the University of Melbourne, co-led the study with colleague Desiree Meszaros.

"We were not talking about 'whole-house' mold infestation that might occur under special circumstances such as following the house being flooded," Burgess said.

While a number of previous studies have examined indoor air pollutants and asthma, the majority focused on children and adolescents, Burgess said, but little research has looked at the relationship between these exposures and asthma in middle-aged adults.

About 25 million Americans have asthma, according to the National Heart, Lung and Blood Institute, and 7 million of them are children. Asthma typically begins in childhood, and often occurs in kids with allergies.

Burgess and his colleagues were interested in the effect of indoor air pollutants on adults' asthma symptoms and also in any differences between responses by those with allergic asthma and those with non-allergic asthma.

"We did this because in older adults, all asthma is not necessarily the same," Burgess said. "In this age group, non-allergic asthma is more common - we surmised that the risk of having 'non-allergic asthma' related to indoor air pollutants might be increased in this older population.

The research team used data from an ongoing study that began in 1968 when the participants were seven years old. In 2004, a total of 5,729 participants filled questionnaires about a variety of health topics, including respiratory symptoms and their home environment.

Participants were asked about asthma, asthma symptoms, amount of visible mold in the home, the number of smokers and types of heating and cooking appliances they had.

About 11.6 percent of the participants had asthma at the time of the 2004 questionnaire. About 17 percent had chest tightness at night and 23 percent reporting wheezing during the previous year. About 30 percent of the participants were smokers and about 15 percent of households included at least one regular smoker other than the study participant.

Almost half reported ever having had mold on any home surface, and about a third said they'd seen mold at home within the last 12 months, according to the results published in Respirology.

Recent household mold exposure was associated with 26 percent greater odds of having asthma, 34 percent greater odds of wheezing and 30 percent greater odds of chest tightness. The authors noted that the more rooms with mold, the worse the asthma symptoms.

For men, mold exposure was linked to almost four times greater odds of having non-allergic asthma, but not for women.

The researchers also found that second-hand tobacco smoke was associated with increased odds of asthma, wheezing and chest tightness in non-smokers.

"We did not find any evidence that the type of stove used in the home for cooking had any effect on asthma," Burgess said. "But we found that having a reverse cycle air conditioner in the home was linked with a 16 percent reduction in the risk of asthma."

The U.S. Environmental Protection offers tips for mold control (here:), urging that mold should be cleaned up promptly and any water problems or leaks should be fixed. Drying any water-damaged areas within 24 to 48 hours can help to prevent mold growth.

Burgess said that to find mold, homeowners should "have a look and have a sniff!"

Most household mold is black, green or yellow and is visible, he said, adding that mold smells.

"We all know the dank smell from mold, so if your nose says mold, you probably have a mold problem," he said.

Getting rid of mold involves two steps, Burgess said.

"First is cleaning it off household surfaces - don't use a dry scrubbing brush - that just spreads the mold around," he said. "And second is ensuring that the room in question is well ventilated and dry. Mold won't grow in dry, well ventilated areas."

Burgess said that methods to actually kill mold spores are debated, with some mold removal experts advising that bleaches will kill mold, while other experts assert that bleaches merely discolor the mold and doesn't kill it.

"For most domestic mold, keep it simple - clean it off and make sure that the place remains dry and well ventilated," he said.