The quality of the air that we breathe indoors is also important for people with asthma. For many people, indoor allergens such as dust mites, pet dander and mould are triggers for their asthma and may be associated with asthma exacerbations. Asthma can be made worse by occupational irritants (work-related asthma), or can be induced by exposure to agents in the workplace (occupational asthma). Cigarette smoke, natural gas, cleaning products and perfumes can also contribute to poor air quality and asthma symptoms.