Germicidal UV Lights May Produce Indoor Air Pollutants. In the ongoing battle against infectious diseases like Covid-19 and the flu, measures like mask-wearing and isolation have taken center stage.
But there’s another crucial tool in the arsenal: ultraviolet germicidal UV lights, which help reduce airborne pathogens.
However, new research from the Massachusetts Institute of Technology (MIT) suggests that these UV lights, while effective in killing germs, may also generate potentially harmful compounds in indoor spaces.
The study underscores the importance of using these lights in combination with proper ventilation.
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Germicidal UV Lights: A Double-Edged Sword
Conventional UV sources, used for disinfection purposes, have long been known for their harmful effects on human eyes and skin.
However, newer UV lights that emit at a wavelength of 222 nanometers are considered safe for use. But according to MIT researchers, the story doesn’t end there.
The study, published in the journal Environmental Science and Technology, reveals that these new UV lights can trigger chemical reactions that lead to the creation of unwanted compounds in indoor environments.
While the researchers don’t advocate avoiding these UV lights altogether, they do emphasize the need for using the right UV light strength for specific indoor situations and ensuring proper ventilation.
Research Team and Their Unexpected Focus
The MIT study, led by recent postdoc Victoria Barber, alongside doctoral student Matthew Goss and Professor Jesse Kroll, involved collaboration with experts from MIT, Aerodyne Research, and Harvard University.
Normally, Kroll’s team focuses on outdoor air pollution, but the COVID-19 pandemic led them to explore the realm of indoor air quality.
Typically, indoor spaces experience little photochemical reactivity, unlike the outdoors where sunlight is constantly present. However, the use of devices that utilize chemical methods or UV light to clean indoor air can introduce a sudden influx of oxidation reactions indoors.
This can have cascading effects, according to Kroll.
The initial interaction of UV light with oxygen in the air leads to the formation of ozone, which, in itself, poses health risks. Furthermore, the creation of ozone sets the stage for various oxidation reactions.
For instance, UV light can react with ozone, producing compounds known as OH radicals, which are potent oxidizers.
Barber notes that when these oxidants interact with volatile organic compounds present in most indoor environments, it results in the generation of oxidized volatile organic compounds that can be more harmful to human health than their unoxidized counterparts.
This process also gives rise to secondary organic aerosols, which can be harmful to breathe.
These compounds pose a particular problem indoors, where people spend a significant portion of their time, and lower ventilation rates can cause these compounds to accumulate at higher levels.
Testing and Key Findings On Germicidal UV Lights
Given their extensive experience studying such processes in outdoor air, the MIT team was well-equipped to directly observe these pollution-forming processes indoors.
They conducted a series of experiments, exposing clean air to UV lights in a controlled environment, and then introducing one organic compound at a time to observe their effects on the compounds produced.
While further research is needed to determine how these findings apply to real indoor settings, the formation of secondary products was evident.
Not a Substitute for Ventilation
The devices using the new UV wavelengths, known as KrCl excimer lamps, are still relatively rare and costly, primarily used in hospitals, restaurants, or commercial settings rather than homes.
Despite some suggestions that these devices might replace the need for ventilation, the MIT study asserts otherwise.
The research findings indicate that these UV lights should not replace ventilation but should instead complement it.
Kroll suggests a balanced approach, where the health benefits of UV light for pathogen deactivation are achieved without a significant buildup of harmful compounds through effective ventilation.
The Road Ahead
The results from the MIT study are based on highly controlled lab experiments using air contained in a controlled environment.
While the findings provide valuable insights into the chemistry occurring under UV light radiation, the next step in the research is to conduct measurements in real-world indoor spaces.
Final Thoughts On Germicidal UV Lights
As Dustin Poppendieck, a research scientist at the National Institute for Standards and Technology, points out, these 222-nanometer radiation devices are being deployed in various indoor spaces without a full understanding of their potential benefits and harms.
This study forms the foundation for a comprehensive evaluation of the health impacts associated with these devices.
It is crucial to complete this process before relying on the technology to prevent future pandemics.
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