Scented cleaners release vast amounts of pollutants indoors

Cleaning with lemon or pine-scented products releases trillions of invisible particles into indoor air, according to a preliminary study by Purdue University researchers reported by ERR. The amount of pollution people inhale while cleaning is comparable to exposure beside a busy road.

Many common cleaning products get their characteristic smell from terpenes such as limonene and alpha-pinene. These volatile compounds are also released naturally by coniferous trees and citrus plants, creating the fresh aroma associated with forests.

Although products containing pine or lemon extracts are often considered safe because of their natural origins, concentrated essential oils can trigger a rapid chain reaction indoors. When cleaning, viruses and bacteria may be removed from surfaces, but large quantities of tiny particles can simultaneously enter the indoor air, said Brandon Boor, the study’s lead author and an associate professor of civil engineering at Purdue University.

Reactive gases can build up quickly in regularly cleaned living rooms. Their concentrations may even exceed the levels of natural terpenes measured in dense forests. In high quantities, the otherwise familiar fragrance compounds can place a burden on the lungs.

Ozone triggers a chemical reaction

Terpenes need sufficient ozone to generate pollution. Ozone usually enters rooms from outdoor air during ventilation, but some household devices can also produce it. Ionising and ultraviolet air purifiers, which became popular during the coronavirus pandemic, can release particularly large amounts of ozone.

When ozone meets vapours from scented cleaning products, a rapid chemical reaction begins. Within minutes, secondary organic aerosols form in the air, producing billions or even trillions of nanoparticles every minute, according to the researchers.

The aerosols form in several stages. Ozone breaks the original terpene molecules into smaller oxygen-containing compounds. These compounds then combine in the air, forming a new solid or liquid particle within a few dozen seconds.

The aerosol cloud cannot be seen with the naked eye. No visible dust or haze forms, even though potentially harmful particles continue to develop in the air, Boor said.