The annual return to school typically triggers a bump in asthma activity, and experts say affected kids and their parents need to focus on asthma control at this time.
The Asthma Society of Canada says as many as a quarter of all trips children make to hospital emergency rooms for asthma problems during the year occur in September.
That surge in cases is known as the September asthma peak and it is believed that the viral infections kids pick up when school resumes provoke their asthma problems.
The Asthma Society says there are ways to lower the risk of flareups, including having children take their asthma medication year round, even when they aren't experiencing symptoms.
They suggest helping children figure out what triggers their asthma and how those triggers can be avoided, as well as having an asthma plan that is shared with school authorities.