ACAAI: Home is Where the Allergies Are

PHILADELPHIA, Nov. 14 -- Home is where the heart is, and increasingly, where allergens lie in wait.

For people with allergies and asthma, home sweet home could be masking a festering stew of molds, dust mites, noxious gases, building debris, and other unhealthy substances, suggested speakers at a symposium held at the American College of Asthma, Allergy & Immunology meeting here.

Variables that can affect the severity of allergic rhinitis and asthma among the occupants of a given house included the age and condition of the house, type and condition of heating and cooling systems, humidity, air flow, indoor tobacco use, pets, and hygiene habits of the occupants, said James L. Sublett, M.D., of the University of Louisville School of Medicine.

"Particularly in the era of energy conservation in the '70s and '80s, a lot of homes, buildings and schools were built very tight," Dr. Sublett said. "These buildings inhale, but they don't exhale. They tend to pull in a lot of air from outside and trap these particles and allergen inside, and there's not good ventilation or air exchange, so you have a buildup of indoor pollution, and the EPA has recognized that this probably more of a risk for us than the outdoor pollution."

He described the case of one of his patients, a five-year-old girl who had had a persistent cough and nasal congestion since age one. Her symptoms occurred year round, but were worse in the fall.

She had been referred by the her school's nurse because she had missed several days of school since starting kindergarten, and had several acute episodes of asthma-like symptoms.

Allergen prick testing showed that she had strong sensitivities to dust mites, horse allergens (her father was an exercise rider at a local horse track), Mucor and Alternaria mold, and grass pollens, but she was negative to cat.

She lived with her parents, a grandmother who smoked, two younger siblings, and an indoor cat. The apartment had forced hot air heating and a window air conditioner, and the family used a vaporizer in the children's bedroom to help with a younger sibling's nasal congestion.

Any or all of these elements could contribute to the five-year-old girl's symptoms, Dr. Sublett said.

Among the recommendations for controlling the allergens in her environment were:

• Ban indoor smoking.
• Keep humidity below 50% (ideally 30%), and do not use humidifiers or vaporizers. Moisture in the home can encourage the growth of molds. Dry nasal passages in drier homes can be treated with moisturizing solutions when necessary, he said.
• Remove wall-to-wall carpeting from the bedroom if possible, and, if not, use a central vacuum or vacuum with a HEPA filter.
• Keep pets out of the bedroom at all times.
• Encase mattresses and pillows in mite-proof covers and wash bed linens regularly.
• Use a high efficiency furnace filter and change it at least every three months.
• Leave the furnace fan on to create a whole house filter to remove particles that may cause allergies.
• Have heating and air conditioning units inspected and serviced every six months, and make sure that gas appliances and fireplaces are properly vented to the outside.

Dr. Sublett said that the use of ionizing air filters is not recommended, because they produce ozone.

"There's a lot of really misleading claims about ionizing filters," he said. "They don't really cure allergy or cure asthma. What they do is reduce the amount of particulates and keep the heating and air conditioning system from becoming contaminated with thing that may then be re-circulated in the indoor environment."

Home designers, builders, and occupants all can play an important role in creating less allergenic housing, said Terry Brennen, MSN, of Camroden Associates of West Moreland, N.Y.

Designers and builders should understand "a building designed without regard for wind and driven rain intrusion will eventually become contaminated by mold," Brennen said.

In addition, decisions made during construction can inadvertently alter air flow in the finished home, causing air from the garage or under the foundation to be brought into occupied spaces.

"The most thoroughly, most cleverly designed ideas to provide good indoor environment can be overcome by a determined or simply unlucky occupant," he said.

His six steps to a healthy indoor environment included:

• Educate designers, builders, occupants.
• Keep the building dry, clean, and pest free.
• Manage potential contaminant sources.
• Provide exhaust ventilation for strong stationary sources.
• Provide filtered, dilution ventilation for the people, interior finishes, and furnishings.
• Reduce unplanned airflows.

Brennen noted that Environmental Protection Administration officials have estimated that "more than 90% of exposure to contaminants people get is indoor, and more than half of the indoor contaminants people breathe are the result of occupant related activities."