Understanding the Risks of Germicidal UV Lights on Indoor Air Quality

Efforts to combat airborne diseases like Covid-19 and the flu have evolved beyond masks and isolation to include advanced filtration and safer ultraviolet light technologies that minimize pathogens in indoor air.

Innovations and Risks of 222nm UV Light

Traditional UV sources pose risks to eyes and skin, but new UV lights emitting at 222 nanometers promise safer pathogen deactivation. However, MIT research reveals these lights may produce harmful indoor compounds, emphasizing the need for proper use alongside ventilation.

The study published in Environmental Science and Technology involves experts from MIT, Aerodyne Research, and Harvard University, marking a shift from outdoor to indoor air quality research during the pandemic.

Indoor Photochemistry and Ozone Formation

Indoor environments lack sunlight-driven photochemistry but introducing UV light can initiate oxidation reactions, creating ozone and hydroxyl radicals that react with volatile organic compounds (VOCs).

“The presence of VOCs indoors means these oxidants can lead to harmful oxidized compounds potentially more dangerous than their original forms.”

These secondary products include oxidized VOCs and organic aerosols that pose breathing hazards, especially in low-ventilation settings where pollutants accumulate.

Laboratory Insights and Practical Applications

Controlled experiments with UV exposure and organic compounds confirm secondary pollutant formation, though real-world impacts require further study.

KrCl excimer lamps using 222nm UV light are mainly used in hospitals and commercial venues due to cost and rarity, complementing rather than replacing ventilation systems.

Balancing Health Benefits and Chemical Risks

Optimal use of UV light involves balancing pathogen deactivation with minimizing pollutant formation through ventilation, as emphasized by Kroll and colleagues.

Ongoing research aims to validate models in real indoor environments, ensuring comprehensive assessment of benefits and risks before widespread adoption.

Funding for this research was provided by the National Science Foundation, Harvard Global Institute, and an NIEHS Toxicology Training Grant.