Indoor environments are exposing people to an increasing mix of new pollutants

Indoor dust, air and everyday products are exposing people to a growing mix of “new pollutants” inside homes, schools and workplaces, according to a new perspective published in the journal New Contaminants. The authors warn that these emerging chemicals may quietly increase the risk of heart disease, cancer and developmental problems while remaining largely unregulated and poorly monitored indoors.

Hidden indoor pollution

People now spend about 90 percent of their time indoors, yet most pollution research and standards still focus on outdoor air. The work highlights that indoor spaces have complex mixtures of chemicals from building materials, furniture, cosmetics, cleaners and electronics that can persist and transform over time. Because modern buildings are more airtight to save energy, pollutants released indoors can accumulate and lead to long-term exposure.​

“In many buildings, indoor pollution can be more severe than what we measure outside, and this is of particular concern to children and older adults who rarely leave these environments,” says corresponding author Wei Du of Kunming University of Science and Technology. “Our daily routines bring us into constant contact with chemical residues in the air, dust and surfaces, even when we can’t see or smell them.”

What are “new pollutants”

Unlike traditional indoor pollutants such as formaldehyde or carbon monoxide, new pollutants include persistent organic pollutants, endocrine-disrupting chemicals, antibiotics, and microplastics that have only recently come under scrutiny. These substances can be released from shampoos, sunscreens, plastics, carpets, paints, toys, electronics, and specialized materials used in offices or child care centers. Once indoors, they can enter the body through inhalation, ingestion of dust or skin contact and have been detected in blood, urine, breast milk and even human bone marrow.​​

Because they can be more dangerous

The authors point out that indoor surfaces and dust act like chemical reactors where pollutants can be transformed into new compounds that may be even more resistant or toxic than the original ones. For example, reactions caused by indoor light, ozone, and other oxidants can convert flame retardants or fragrance ingredients into derivatives with stronger neurotoxic or endocrine effects. These processes make it more difficult to predict health risks using only outdoor studies and highlight the need for dedicated indoor research.​

A call for standards and protection

The perspective calls for systematic monitoring of new contaminants in different indoor settings, including homes, schools, hospitals, offices and recreational facilities to create a comprehensive database for regulatory authorities. The authors argue that high-resolution measurements, mechanistic studies of chemical transformations, and targeted toxicological work are urgently needed to inform next-generation indoor air standards. “Protecting human health increasingly means looking inward to the places where we live, learn and work, and treating indoor environments as a critical frontier for pollution control,” says columnist Bo Pan.