There are a number of different things that can cause the quality of the air inside your home to be poor, including:
VOCs - Volatile organic compounds, or VOCs, can be found in paints, fragrances and cleaning supplies. These chemicals can cause health problems when used in high concentrations.
Smoking/Vaping Indoors - Tobacco smoke and e-cigarette vapor contain particulate matter that can be harmful.
Gas Stoves - Stoves that use gas emit carbon monoxide and nitrogen dioxide. Running the ventilator hood will help remove these gases but some could still linger in a home.
Mold - Homes with mold can cause serious health concerns.
Pets - The dander and hair from pets increases allergens in your home’s air.