"Dust is bad in winter, said Crabtree.Asthma can also be triggered by allergens such as pollen or pet dander, tobacco smoke, poor air quality, and chemical fumes.People who are in contact with asthma sufferers, especially parents of children with asthma, \"should never smoke in the house, said Edwards.Edwards and Crabtree see many cases of asthma that are caused by rhinitis, which occurs when airb" . . . . .