Clean Air

CSU Study Reveals Potential Health Consequences of Air Purifiers

• By Matt Jones
• 03/30/21

During the COVID-19 pandemic, air purifiers are growing in popularity as a method of cleansing interior spaces of the airborne SARS-CoV-2 virus. However, a new study from Colorado State University has revealed some of the unintended consequences of some of these devices.

The study discovered that cleansing the air of one harmful pollutant can create others. In chamber and field tests, ionizing devices that decreased the number of volatile organic compounds (VOCs) like xylenes, also increased the number of oxygenated VOCs like acetone and ethanol, as well as toluene, which can be found in substances like paint strippers and pesticides. The EPA reports that exposure to VOCs can lead to negative health effects like eye, noes, and throat irritation; headaches; nausea; loss of coordination; and damage to liver, kidney, and central nervous systems.

One popular type of air purifier is an ion-generating system, including bipolar ionization devices, that charge particles to separate them from the air faster. They’re marketed for their ability to kill fungi, viruses, and bacteria. However, cautions CSU chemist and co-leader of the study Delphine Farmer, “We should have a much better understanding of these effects before widespread use of these types of devices.”

The study uncovered that within the air purifier marketplace, there exist “inadequate test standards, confusing terminology, and a lack of peer-reviewed studies of their effectiveness and safety.” The study comments that there has been comparatively little research in “additive” air-cleaning methods as compared to air filtration.

The study reports that ions added to the air in habited environments like offices and classrooms can react with compounds present in the air that may or may not be present under ideal testing conditions. These additions could form harmful substances like ozone or formaldehyde.

“Manufacturers and third-party test labs commonly demonstrate their product’s effectiveness using chamber tests, but these test reports often don’t use experimental conditions that could show how the device actually performs in real-world conditions,” said Brent Stephens, chair of the Illinois Tech Department of Civil, Architectural, and Environmental Engineering, and a co-author of the study. “To the extent that there are testing standards for ionization and other devices, these are largely industry-led standards that remain underdeveloped at this point, focused mostly on ensuring just one pollutant—ozone—is not generated during operation.”

The health impacts of air ionization devices remain unknown. A few recent studies have revealed some potentially negative consequences, though. One study associated exposure to negative ions with an increase in systemic oxidative stress levels. Another showed that ionizers may have a negative effect on heart rate variability.

“Without peer-reviewed research into the health impacts of these devices, we risk substituting one harmful agent for another,” Stephens said. “We urge others to follow guidance from organizations like the U.S. EPA and ASHRAE, which generally recommend the use of established, evidence-based measures to clean indoor air, including high-efficiency particle filtration and enhanced ventilation, in addition to face coverings and physical distancing, to help reduce airborne transmission of COVID-19.”