Molds are found everywhere in nature and frequently indoors as a component of household dust. However, when mold spores are present in large amounts they can pose a health hazard to humans through allergic reactions and respiratory issues. Additionally, some molds also produce mycotoxins that can pose serious health risks to humans and animals.

The amount of lead-based paint in housing is significant. Approximately 64 million private homes in the United States contain at least some lead-paint. Children living in homes with lead-based paint can become exposed by eating paint chips, chewing on surfaces painted with lead paint or most commonly by ingesting lead-bearing dust.

A variety of sources can be attributed to allergens including dust mite excretion, pollen and pet dander. Allergens produced by house dust mites are among the most common triggers of asthma. And while animals allergens are most often found in homes with a pet, surprisingly they are also found in places where pets have never been present, like schools and workplaces.