|Increased Allergen Levels in Homes Linked to
Results from a new national survey demonstrate that elevated allergen
levels in the home are associated with asthma symptoms in allergic
individuals. The study suggests that asthmatics that have allergies
may alleviate symptoms by reducing allergen exposures inside their
homes. The work was carried out by researchers at the National
Institute of Environmental Health Sciences (NIEHS), the University
of Iowa, Rho Inc., and the Constella Group. The team's findings
may help millions of Americans who suffer from asthma.
"Indoor allergen exposures are of great importance in relation
to asthma because most people spend a majority of their time indoors,
especially at home," said Darryl Zeldin, M.D., a Principal
Investigator in the Laboratory of Respiratory Biology at NIEHS
and senior author on the paper.
Asthma is one of the most common chronic ailments in the United
States, affecting more than 22 million people. Asthma has been
shown to be triggered by a wide range of substances called allergens.
The findings, published online and available in the March issue
of the Journal of Allergy & Clinical Immunology, show
that exposure to multiple indoor allergens was common in U.S. households
with 52 percent having at least six detectable allergens and 46
percent having three or more allergens at increased levels. The
indoor allergens studied included those from dog, cat, mouse, cockroach,
dust mite, and the fungus Alternaria.
The researchers used data from the National Survey of Lead and
Allergens in Housing (NSLAH) to examine factors that contribute
to high allergen levels in homes and to determine whether elevated
household allergen levels were associated with occupants' asthma
status. The NSLAH, which was the first study to characterize how
allergen exposures vary in homes at the national level, surveyed
the homes of nearly 2500 individuals in 75 locations throughout
the U.S. The survey was jointly funded by the NIEHS and the U.S.
Department of Housing and Urban Development.
Several factors were found to contribute to the increased concentrations
of allergens, including race, income, type of home, and sources
of allergens, such as presence of pets and pests. The study also
showed that homes with children were less likely to have high allergen
levels. The authors noted that this finding may not be surprising
since homes with children may be cleaned more frequently than homes
without children. Regular household cleaning is a simple yet effective
regimen that helps to reduce the overall exposure burden.
According to lead researcher Päivi Salo, Ph.D., of NIEHS, the
study provides useful information to asthma patients. "Our
results highlight the importance of reducing exposure to allergens
as a fundamental part of asthma management," she said. "Although
homes cannot be made allergen free, asthmatics that have allergies
may need to do a better job in reducing allergen levels in their
homes to improve asthma control."
This finding is the first to provide information on total allergen
burden in U.S. homes and how it relates to asthma. "This study
confirms that indoor allergens play a major role in asthma," Zeldin
Salo and her co-authors, however, point out that more research
is needed to understand the complex relationships between genetic
and environmental factors that cause asthma, particularly the role
that indoor allergen exposure plays in the development of asthma. "Although
reducing allergen levels in the home may not prevent individuals
from developing asthma, reducing exposure levels is crucial for
those whose asthma is allergic in nature." Zeldin concluded.
The primary mission of the National Institute of Environmental
Health Sciences (http://www.niehs.nih.gov/)
(NIEHS), one of 27 Institutes and Centers at the National Institutes
of Health, is to reduce the burden of human illness and disability
by understanding how the environment influences the development
and progression of human disease. For additional information, visit
the NIEHS Web site at http://www.niehs.nih.gov/ or
for more specific information about asthma, please visit http://www.niehs.nih.gov/health/topics/conditions/asthma/allergens.cfm.
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and
its programs, visit www.nih.gov.