Physicians are warning parents to be aware of the increased risks of asthma exacerbations for children in September they head back to school, according to NBC KULR8 (Billings, Mont).

Specifically for kindergarten and first graders, according to a new study, asthma symptoms are increasing when they head back to school. This is because there’s more germs and allergen exposure. Even the dust from the chalkboards can irritate a child’s asthma.

In fact, doctors say one-fourth of all asthma exacerbations happen during September.