Indoor environments are exposing people to an increasing variety of new chemical contaminants, according to a perspective published in the journal New Contaminants. The study notes that while most pollution research and standards focus on outdoor air, people now spend about 90 percent of their time indoors, where they may encounter more complex mixtures of pollutants.
The paper explains that modern buildings are often designed to be airtight for energy efficiency, which can lead to the accumulation of chemicals released from building materials, furnishings, cleaning agents, electronics, and personal care products. These substances can persist in indoor air and dust and may transform into other compounds over time.
"In many buildings indoor pollution can be more severe than what we measure outside and that is especially worrying for children and older adults who rarely leave these environments," said 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 on surfaces even when we cannot see or smell them."
Unlike well-known indoor pollutants such as formaldehyde or carbon monoxide, the report identifies new contaminants including persistent organic pollutants, endocrine disrupting chemicals, antibiotics, and microplastics. These substances are found in everyday items like shampoos, plastics, carpets, paints, toys, electronics, and materials used in offices or childcare centers. Once inside a building, they can enter the body through inhalation of air or dust or by skin contact. Traces have been detected in blood, urine, breast milk, and even bone marrow.
The authors also highlight that indoor surfaces and dust can act as sites for chemical reactions that create new compounds. Light exposure or oxidants like ozone may transform flame retardants or fragrance ingredients into derivatives with stronger neurotoxic or hormone-disrupting effects. These changes complicate efforts to assess health risks based only on outdoor studies.
To address these concerns, the perspective calls for systematic monitoring of emerging contaminants across various indoor settings such as homes, schools, hospitals, offices and recreational facilities. The authors recommend comprehensive databases for regulators along with advanced measurement techniques and toxicology studies focused specifically on indoor environments.
"Protecting human health increasingly means looking inward at the places where we live, learn and work and treating indoor environments as a critical frontier for pollution control," said co-corresponding author Bo Pan.
