WASHINGTON (TIP): Cleaning products and air fresheners, which provide a pleasant smell to your house, may also spike indoor aerosol levels and hamper the quality of air, a new study has warned. “Some of the same chemical reactions that occur in the atmosphere as a result of smog and ozone are actually taking place in your house while you are cleaning,” researchers said.

In a new study, researchers took a closer look at these reactions, which involve an organic compound – called limonene – that provides the pleasant smell of cleaning products and air fresheners. The research helps determine what byproducts these sweet-smelling compounds are adding to the air while we are using them to remove germs and odours. Secondary organic aerosols (SOAs) are microscopic particles created when ozone reacts with volatile organic gases such as limonene – the chemical name for the smell of oranges – or its cousin alpha-pinene, which is part of the smell of pine trees.

“SOAs can come from ozone reactions with numerous sources, especially with compounds called terpenes that produce the scents we associate with cleaners, pine, lavender, and oranges,” Michael Waring, an assistant professor in Drexel University’s College of Engineering, said. Waring and his team used an air testing chamber that they specifically designed to study the reactive behaviour of air in an indoor environment. By adjusting elements of the test, such as the air exchange rate, which is the number of times per hour indoor air is replaced by outdoor air, as well as the concentrations of terpene and ozone in the chamber, the group was able to ascertain how those variables each affected the formation of secondary organic aerosols.

“We found that one of the biggest factors contributing to SOA formation by limonene ozonolysis was the air exchange rate,” Waring said. “This is because certain chemical reactions that form SOAs take longer than others. If the air is exchanged before these reactions can take place then the SOA production is weaker indoors,” said Waring. With 18 different scenarios tested, the team calculated a range of peak formation of secondary organic aerosols when typical concentrations of limonene were introduced to ozone-rich environments with a range of air exchange rates.

“Our findings show a significant enough range of SOA formation to warrant more in depth public health studies,” Waring said. “This research is particularly necessary in order to understand health impacts on people who use significant amounts of cleaning products such as house-cleaners or custodians,” said Waring. The resulting mass concentration of secondary organic aerosols was roughly between five and 100 microgrammes per cubic metre.