Scientists Raise Health Concerns Over Unproven Air Cleaners

Education | Infection Mitigation | HVAC Equipment

Scientists Raise Health Concerns Over Unproven Air Cleaners

School Districts Urged to Only Use Proven Technologies to Mitigate COVID-19

A group of leading scientists recently cautioned school systems and municipalities against adopting unproven air cleaning technologies in the race to mitigate the spread of the SARS-CoV-2 virus.

Authors of the open industry letter note that formal studies of some electronic air cleaning technology indicate “a much lower degree of effectiveness in real-world conditions than typically claimed by manufacturers.”

Specific caution is directed toward air-cleaning equipment that uses electricity to charge particles with “plasma (positive and/or negative ions formed by charging major components of air as well as pollutant molecules), or by photocatalytic oxidation.”

According to the researchers, the process of disinfecting airstreams with plasma, photocatalytic oxidation (PCO) or bipolar ionization technology “may create one or more reactive oxygen species (ROS), ozone, hydroxyl radicals, superoxide anions, gaseous hydrogen peroxide, and others.”

Scientists Advocate Device Removal to Avoid Student Harm

Investigators caution that some electronic air cleaners can worsen classroom air quality so much so that authors “recommend that these [school] districts strongly consider turning off or disabling these electronic air cleaners to prevent unintended harm to building occupants.”

They argue that incomplete data and exaggerated claims made about some electronic air cleaning devices are often not indicative of real-world performance results such as classrooms.

“For example, one recent independent test of needlepoint bipolar ionization (NPBI) technology found that the strength of the ions produced appears insufficient to effectively clean the air and the device also produces volatile organic compounds (VOCs).”

Additionally, the Bureau of Toxic Substance Assessment (BTSA) performed a study of indoor air quality (IAQ) in a high school classroom monitoring changes in IAQ resulting from an installed bipolar ionization (BPI) product in the air handling unit serving the classroom. The study found higher levels of ozone and ultrafine particles and concluded that the IAQ worsened with the ionization device in operation.

Effective (and recommended) Means of Mitigating Classroom Infections

Instead, researchers encouraged school systems to adopt technologies that have been successfully proven in real-world settings and endorsed by multiple scientifically proven and peer-reviewed studies.

“The proven measures that should be taken to address airborne transmission risk include:

  • properly sized and maintained ventilation (mechanical and natural),
  • mechanical filtration (including portable HEPA filter units), and
  • germicidal ultraviolet light systems.”

These recommendations align with long-standing industry guidance from ASHRAE in the control of airborne infections. As part of its Position Document on Infectious Aerosols, developed by the Society’s Environmental Health Position Document Committee, ASHRAE states:

“Dilution and extraction ventilation, pressurization, airflow distribution and optimization, mechanical filtration, ultraviolet germicidal irradiation (UVGI), and humidity control are effective strategies for reducing the risk of dissemination of infectious aerosols in buildings and transportation environments.”

Danger of Ozone

The letter states that despite ASHRAE Standard 62.1 capping ozone emission levels from an air cleaner at 5 ppb, some third-party testing recorded exponentially higher levels of the harmful gas.

In a CDC/FEMA study, it was found that “a certain bipolar ionization device increased the level of ozone to more than 1,000 ppb even though the device has published test data showing zero ozone production and has obtained UL‑867 certification.” Ozone (O3) is a toxic gas that can cause respiratory tract irritation, asthma and even permanent lung damage.

In a separate guidance document exploring ozone and its impact on indoor air quality, the Centers for Disease Control and Prevention states, “if used at concentrations that do not exceed public health standards, ozone applied to indoor air does not effectively remove viruses, bacteria, mold, or other biological pollutants.”

Against Public Funding

Study authors implore school administrators to only use air cleaners for which evidence of effectiveness and safety is clear. “None of the $176 billion approved over the last several months by the Federal government for K-12 COVID relief aid should be spent on this unproven technology,” the letter states.

Authors call on regulatory agencies and professional industry associations to require supporting test data that document both the efficacy and health safety of electronic air cleaning equipment.

The letter concludes: “We ask that school district facility managers and administration leadership, as well as the relevant national and international bodies and Architecture, Engineering and Construction (AEC) industry consultants, recognize the unproven nature of electronic air cleaning equipment and avoid wasting valuable emergency COVID relief aid dollars installing it within school facilities”