There are many reasons why children get sick in the fall after they return to school. These include virus infections, home environment as well as school environment. I will address each of these issues separately.

During the summer months, most children spend much of their time outdoors. A few of them can get infected with viruses that cause “colds.” Because children are outdoors much more in the summer, these viruses don’t have the chance to spread around. However, when these infected children return to school and stay with their friends and classmates for many hours every day, it is much easier for these viruses to spread around within the school. As you may already know, there are literally thousands of respiratory viruses. As a result, a child can get sick with one virus after another.

There is actually very little anyone can do if these “colds” that you referred to are due to virus infections. Children have no immunity to viruses until they get infected. Therefore, young children tend to get sick more often, and they build up immunity t afterwards o these viruses. By the time they enter junior and senior high school, they would have been infected with many viruses and would get colds less often.

Much to the parents dismay, children often bring these viruses home and infect their siblings as well as their parents. As a result, many families have to go through the trouble of sick children and parents during the fall season.

Another possible cause of sick children in the fall is the home environment. This may be quite a surprise to you. As we all know, many communities in Canada turn much cooler in September and October. Families often close their doors and windows to keep their house warm. With better insulation and tighter windows, much of the indoor allergens and pollutants stay inside the house instead of escaping through leaky walls and windows.

Indoor allergens include dust mites (in the dust), animal dander (shedding from all furry animals), and mildew (in damp places like basement and around windows). Indoor pollutants are cigarette smoke, sprays, perfumes, air-fresheners, cleaning agents, and fresh paints. All of these things can irritate the sensitive airway of children, especially those who have allergies and asthma. Their symptoms can be very similar to virus infections, with sneezing, stuffy nose, headaches, sore throat, and sometimes cough.

You are right to be concerned about the environment in school. Much of the indoor allergens and pollutants are also present in school. Many schools still have carpets in the classroom or corridors. They are the best places for dust mites to grow. Mildew will grow in any place that is damp. Leaky walls and windows, drinking fountains, and spills in carpets are ideal places for mildew. Most schools are closed for the summer, the temperature inside the schools can stay quite warm. Warm and humid conditions are just the right environment for both dust mites and mildew to flourish.

When schools open in September, it is quite possible that larger amounts of dust mites and mildew are still inside, especially if the ventilation system is not functioning adequately. Right now scientists have not conducted research to prove that this is actually happening in schools, but the condition certainly is there for it to happen. Fortunately many schools are removing carpets and replacing them with other floorings which are harder for dust mites and mildew to grow.

If your children always get sick in the fall, I would suggest that you look at your own home environment first, and see whether you can reduce some of the allergens and irritants that I have mentioned above. After you have already done that, and if your children still get sick more often than expected, then you may want to approach your local school authority or the home school association. Talking to other parents may give you some idea whether the school environment is actually the cause of your children’s illness.