This week, ProPublica exposes the invisible danger of formaldehyde

Formaldehyde, a colorless pungent gas, can cause cancer, breathing problems and reproductive harms.

Most of us face the highest risks in our homes, where formaldehyde is released by some types of furniture, gas stoves and other everyday products.

Because of its importance to many industries, formaldehyde has proven difficult to regulate.

Some formaldehyde is listed on the product label as formalin or methylene glycol.

Some nail hardeners and polishes contain formaldehyde that may be listed on product labels.

The EPA has determined that continuous daily exposure to concentrations of formaldehyde above 7 micrograms per cubic meter of air may cause decreased lung function, trigger allergic reactions.

The average level of formaldehyde inside an American home is 23.2 micrograms for every cubic meter of air.

About 10% of homes have levels above 41 microgram, which is almost 6 times the EPA 's target.

Researchers have found unhealthy concentrations of the chemical in child care centers, funeral homes and even bakeries.