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
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
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
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
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.
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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.
Respirology, online Feb. 12, 2014.
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