The findings were recently reported in the journal Environmental Science and Technology, in a paper by current MIT postdoc Victoria Barber, doctoral trainee Matthew Goss, Professor Jesse Kroll, and six others at MIT, Aerodyne Research, and Harvard University.
While Kroll and his group generally deal with concerns of outside air contamination, during the pandemic they ended up being significantly interested in indoor air quality. Generally, little photochemical reactivity happens indoors, unlike outdoors, where the air is continuously exposed to sunshine. However with using gadgets to tidy indoor air utilizing chemical approaches or UV light, “all of a sudden a few of this oxidation is brought inside,” activating a prospective cascade of responses, Kroll says.
At first, the UV light engages with oxygen in the air to form ozone, which is itself a health risk. “But likewise, as soon as you make ozone, theres a possibility for all these other oxidation reactions,” Kroll says. The UV can engage with the ozone to produce compounds called OH radicals, which are likewise effective oxidizers.
Barber, who is now an assistant teacher at the University of California at Los Angeles, includes, “If you have volatile natural substances in the environment, which you do generally in all indoor environments, then these oxidants respond with them and you make these oxidized unpredictable organic substances, which in some cases end up being more harmful to human health than their unoxidized precursors.” The procedure also results in the development of secondary natural aerosols, she says. “Again, this things is hazardous to breathe, so having it in your indoor environment is not perfect.”
Indoor Air Quality and UV Light
The development of such compounds is especially problematic in the indoors, Kroll states, due to the fact that individuals spend a lot of their time there, and low ventilation rates can suggest these compounds might accumulate to relatively high levels.
Having actually studied such processes in outside air for many years, the team had the best devices in hand to observe these pollution-forming processes inside your home straight. They carried out a series of experiments, first exposing tidy air to the UV lights inside a controlled container, then including one organic compound at a time to see how they each affected the substances that were produced. More research study is required to see how these findings apply to genuine indoor environments, the formation of secondary items was clear.
UV Technology and Ventilation
The devices that make usage of the brand-new UV wavelengths, called KrCl excimer lights, are still reasonably rare and costly. Theyre used in some medical facility, restaurant, or commercial settings instead of in homes. While they have actually in some cases been promoted as an alternative for ventilation, especially in hard-to-ventilate older buildings, the brand-new research study suggests thats not appropriate. “Our big finding was that these lights are not a replacement for ventilation, but rather an enhance to it,” states Kroll, who is a teacher of ecological and civil engineering, and of chemical engineering.
Some have proposed that with these gadgets, “perhaps if you could simply shut down the viruses and germs inside, you wouldnt require to stress over ventilation as much. What we showed is that, regrettably, thats not always the case, since when you have less ventilation, you get an accumulation of these secondary items,” Kroll says.
He suggests a various method: “There might be a sweet spot in which youre getting the health advantages of the light, the deactivation of pathogens, however not too many of the disbenefits of the contaminant formation due to the fact that youre ventilating that out.”
Implications and Future Research
The outcomes so far are from exactly managed laboratory experiments, with air included in a Teflon bag for screening, Barber mentions. “What were seeing in our bag is not necessarily directly similar to what you would see in a genuine indoor environment,” she says, “however it does offer a pretty great picture of what the chemistry is that can occur under radiation from these gadgets.”
Goss adds that “this work permitted us to confirm a basic design that we might plug in criteria to that are more appropriate to real indoor spaces.” In the paper, they use this details “to attempt to use the measurements weve taken to approximate what would occur in an actual indoor space.” The next step in the research study will be to attempt follow-up research studies taking measurements in real-world indoor spaces, he says.
” Weve revealed that these are a possible issue,” Kroll says. “But in order to understand what the full real-world implications are, we need to take measurements in real indoor environments.”
” These 222-nanometer radiation gadgets are being deployed in bathrooms, class, and conference rooms without a complete accounting of the potential benefits and/or harm relate to their operation,” says Dustin Poppendieck, a research study researcher at the National Institute for Standards and Technology, who was not connected with this study. “This work lays the foundation for an appropriate metrology of potential unfavorable health impacts of these devices. It is necessary this process is finished prior to relying on the technology to help prevent the next pandemic.”
Recommendation: “Indoor Air Quality Implications of Germicidal 222 nm Light” by Victoria P. Barber, Matthew B. Goss, Lesly J. Franco Deloya, Lexy N. LeMar, Yaowei Li, Erik Helstrom, Manjula Canagaratna, Frank N. Keutsch and Jesse H. Kroll, 12 October 2023, Environmental Science & & Technology.DOI: 10.1021/ acs.est.3 c05680.
The work was supported by the National Science Foundation, the Harvard Global Institute, and an NIEHS Toxicology Training Grant.
By David L. Chandler, Massachusetts Institute of Technology
November 10, 2023
New research study from MIT shows that while more recent UV source of lights at 222 nanometers, created to reduce airborne pathogens, are more secure than conventional UV, they can produce hazardous compounds indoors. Credit: José-Luis Olivares, MIT; iStock
While beneficial for eliminating pathogens consisting of SARS-CoV-2, the lights may cause unwanted chemical reactions and should be utilized with ventilation, researchers state.
Numerous efforts to decrease transmission of diseases like COVID-19 and the flu have focused on measures such as masking and isolation, however another helpful approach is minimizing the load of air-borne pathogens through filtration or germicidal ultraviolet light. Conventional UV sources can be hazardous to eyes and skin, however more recent sources that emit at a different wavelength, 222 nanometers, are considered safe.
Potential Hazards of UV Light Usage
New research from MIT reveals that these UV lights can produce possibly hazardous substances in indoor areas. While the scientists emphasize that this does not indicate the new UV lights should be avoided totally, they do say the research recommends it is essential that the lights have the right strength for a given indoor situation, which they are used in addition to suitable ventilation.
With the use of devices to clean indoor air using chemical approaches or UV light, “all of an unexpected some of this oxidation is brought inside your home,” activating a potential waterfall of responses, Kroll states.
The UV light communicates with oxygen in the air to form ozone, which is itself a health danger. They brought out a series of experiments, initially exposing clean air to the UV lights inside a controlled container, then including one natural substance at a time to see how they each affected the compounds that were produced. “Our big finding was that these lights are not a replacement for ventilation, however rather a complement to it,” says Kroll, who is a professor of ecological and civil engineering, and of chemical engineering.
The next step in the research will be to try follow-up studies taking measurements in real-world indoor areas, he states.