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Column originally published Aug 25, 2009

There Are Many Triggers For Asthma In The House

Question: Our eight-year-old son has been coughing for years. We thought that he didnʼt wear enough clothes and catch colds easily. He used to take antibiotics many times a year. Finally, our family doctor told us that he has asthma. She gave him puffers which did relieve his cough, but every time when we tried to cut back the puffers, his cough would get worse. We went to the Asthma Education Centre and learned that there are lots of things around the house that likely make his asthma worse. We have carpet throughout the house, we have forced-air heat and we use a wood stove. We are now debating whether it is better to renovate or to buy a new home. Please give us some advice.


I know it is hard to decide whether to make big changes to your home or to build a new one. Let me put things in some perspectives that hopefully will help you to make the best decision for your family.

One of the biggest challenges for those who have asthma is dust inside their homes. In the humid environment in most Canadian homes, tiny insects called dust mites not only survive, they grow very well. They love the warmth and moisture in our pillows, mattresses, and beddings. Even in the dry environment of Alberta, these dust mites still survive in the bedroom because of the heat and moisture of our body which provides the right environment in the bed for them to grow. The condition is even better in Atlantic Canada, where humidity is high inside the home most of the time.

You may have learned that dust mites feed on the skin cells that come off our body every day. It is their droppings that trigger allergy and asthma. A few simple steps can reduce your sonʼs exposure to dust mites around him. You can put the mattress, box spring, and pillows in plastic covers which have zippers that can seal them completely. When they are sealed, dust mites cannot get through to your son. Plastic sheet that covers the top of mattress is not sufficient. Fabric covers wonʼt be tight enough to pre- vent microscopic particles like dust miteʼs dropping from passing through.

Most families have stuffed toys which collect dust. If your son is not attached to them, put them away in a plastic bag. Don’t let them come out; better yet, give them away. Otherwise it is best to allow only a few small ones that can be put through washer and dryer once a week. Larger ones may be hard to dry completely, and mold can grow inside which creates a greater health problem. You may need to put the stuffed toys through a second drying cycle.

Carpet is a serious problem. Although it feels nice to walk on bare feet, it can accumulate large amounts of dust that cannot be removed by vacuuming. Shampooing the carpet cannot remove very much dust either. It can be even worse because some water likely will be left behind, which can promote the growth of mold. It is best to remove the carpet from your sonʼs bedroom first, followed by the piece in his play area. Over time, you should consider removing all carpets from your house.

Your next challenge is the forced-air heating system. Although it is an efficient way to heat the house, it collects lots of dust inside the duct system. Vacuuming the ducts with your vacuum cleaner is not useful at all. You need to hire a duct-cleaning company to thoroughly remove dust from the whole ductal system once a year.

If your house has an air-exchange system, make sure it is adjusted properly so that there is no moisture accumulation on the window, especially in winter time. Air exchange system also involve ducts that circulate air around the house. They need regular service and cleaning as well.

Mold is another important trigger for allergy and asthma. Mold needs moisture and cool temperature to grow. As a result, they are found around moist windows, inside bathrooms, anywhere there is water-leak, as well as in basements.

Most basements in Atlantic Canada are cool and damp, especially in spring and summer. Since you use a wood stove, you may be storing wood in the basement. This will bring even more moisture and mold into your basement. It is much better for you to stack the wood outside, in a wood shed, or against the side of the house, and only bring in enough for the dayʼs use.

Although wood stove is nice a cozy, it is very hard to control the temperature inside the house. Heat can dry the air excessively; some children can have nosebleeds as a result. Some parents use a humidifier or vaporizer to add moisture back. Unfortunately, it is impossible to regulate the humidity: too much moisture will promote the growth of mold, which is dangerous for everyoneʼs health.

The best way is stop burning wood and keep the house cool. It is much more healthy for everyone to wear long-sleeve clothes and sweaters indoors in winter than to heat the house excessively and wear T-shirt and shorts. It is also important to reduce humidity in basement using a dehumidifier that can take away humidity and reduce the growth of mold.

In the last few years, some parents have found it useful to put an air-purifier with HEPA (high-efficiency particulate air) filter in their childʼs bedroom. These machines suck air through a special HEPA filter that can remove dust and other tiny particles in the air, thereby reducing some of the triggers of allergy and asthma.

It is not possible for me to tell you whether you should build a new home or renovate your present house. If you begin by covering his mattress, box spring, and pillow, which you need to do anyway, this alone can be helpful for him. If you end up building a new house, remember that a lot of chemicals are being used nowadays to build and insulate new houses, and you need to open all the windows for a while to allow these chemicals to escape.