The World Health Organization (WHO) says:

Indoor air pollution – such as from dampness and mould, chemicals and other biological agents – is a major cause of morbidity and mortality worldwide.

Molds grow on surfaces and in hidden areas such as in carpet, appliances, mattresses, furniture, plants, attics, insulation, under tile, linoleum and sub-flooring, behind wallpaper, between the slab and foundation, inside closets, walls, ductwork and crawl spaces, etc.

The increased health risks and economic impact from mold and microbial growth resulting from indoor dampness are recognized as significant public health problems requiring attention and proven remediation procedures.

The U.S. Centers for Disease Control (CDC) says:

If you have a breathing problem like asthma, do not enter a building with mold damage. Mold can make asthma symptoms worse.

Children should also NOT enter buildings with mold damage.

The U.S. Centers for Disease Control (CDC) says:

If you have a weakened immune system (such as from cancer treatment or medicines that suppress the immune system), do not enter a building with mold damage. People with a weakened immune system are more likely to get a serious illness from mold.

1989 Massachusetts paper

The 1989 report from the Commonwealth of Massachusetts on indoor air pollution states that sick building syndrome has been known since World War I.

The first published research paper on sick building syndrome was published in England in 1948.

What about air quality tests?

Airborne fungal testing is rarely done, but it may be useful if building occupants are experiencing symptoms that seem to be mold-related and a visual inspection and sampling have failed to locate mold. Keep in mind that airborne testing does not provide reliable data on the average mold content in a home—instead, it provides a “snapshot” of mold levels, which vary considerably over the course of hours, days, weeks, and months. Mold spores are not typically found in the air because they are too heavy.

(Note: Insurance companies, landlords and other defendants may  sometimes manipulate the conditions inside the home in order to get a false result. For example, they will run the air conditioner to make the house very cold and stop all fans to reduce the chances of finding spores in the air.)

What about collecting samples?

Bulk or surface sampling may be helpful in identifying specific mold contaminants in connection with a medical evaluation or in confirming the presence of mold if a visual inspection is unclear. Bulk sampling involves removing and collecting visible mold from surfaces, while surface sampling involves wiping a surface or

There are additional procedures including checking the level of humidity in various areas inside the home, identifying hidden areas of moisture inside the walls, testing for bacteria and small particulates, visually inspecting the home for structural problems, leaks, water damage and signs of water intrusion, etc.

Consult an expert for proper testing and evaluation.