California Air Resources Board

Principal Investigator/Author(s): Theresa Pistochini

Co-Authors: Deborah H. Bennett, Hanieh Khoshnevis Ansari

Contractor: University of California, Davis

Contract Number: 24RD017

Project Status: Completed April 2026

Relevant CARB Programs: Indoor Air, Air Cleaners & Ozone Generating Products

Topic Areas: Air Pollution Exposure, People at Risk, Indoor Air Quality & Exposure, Indoor Air, Health Effects of Air Pollution, Health & Air Pollution, Community Health

Research Summary:

There are many types of air purification devices that use different air cleaning technologies and can improve indoor air quality by removing potentially harmful particles, gases, and pathogenic substances. Some technologies used in air cleaning devices generate ozone, which is an air pollutant and can cause health effects.  Germicidal ultraviolet light with a wavelength of 222nm (GUV₂₂₂) is an air cleaning technology that generates ozone and is used in public spaces. Questions have been raised about the amount of ozone produced by GUV₂₂₂  devices and whether this could negatively affect indoor air quality or pose a health risk.

The research team conducted an extensive literature review and interviewed subject-matter experts to gather information about GUV₂₂₂ air cleaning technology.  Through modeling, they characterized the ozone-related impacts of a ceiling-mounted GUV₂₂₂ system on the indoor air quality of a school classroom, which was compared to indoor ozone levels produced by increased ventilation.  The researchers also identified key information gaps and proposed future research needed to address unanswered questions.

Keywords: air cleaners, air purifiers, ultraviolet, indoor air pollution, ozone, public health, indoor exposure and health effects

Related Work:

• Air cleaner information for consumers
• Research contract 22RD003: Air Pollutant Emissions and Possible Health Effects Associated with Electronic Air Cleaners (2023)

Research Seminar