Formation of Secondary Organic Aerosols by Germicidal Ultraviolet Light
Ultraviolet (UV) light with a wavelength of 254 nm is known to be germicidal, and thus has been increasingly employed as a method of disinfection for indoor environments. Solar UV wavelengths (300 to 400 nm) are known to initiate the formation of secondary organic aerosol (SOA) particles from the ph...
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| Format: | Article |
| Language: | English |
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MDPI AG
2019-01-01
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| Series: | Environments |
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| Online Access: | https://www.mdpi.com/2076-3298/6/2/17 |
| _version_ | 1798004013193494528 |
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| author | Eureka Choi Zhongchao Tan William A. Anderson |
| author_facet | Eureka Choi Zhongchao Tan William A. Anderson |
| author_sort | Eureka Choi |
| collection | DOAJ |
| description | Ultraviolet (UV) light with a wavelength of 254 nm is known to be germicidal, and thus has been increasingly employed as a method of disinfection for indoor environments. Solar UV wavelengths (300 to 400 nm) are known to initiate the formation of secondary organic aerosol (SOA) particles from the photo-oxidation of volatile organic compounds (VOC) in the atmosphere, but germicidal wavelengths have not been extensively studied for indoor environments. In this work, toluene was exposed to 254 nm UV light in a laboratory photoreactor while varying the conditions of the air, the duration of UV exposure, and the duration of post-UV time. The number of particles formed in the fine particulate matter (PM2.5) size range was measured, and significant levels of particle formation were observed for UV exposure periods of as short as 5 min. The particle formation ranged from 2.4 × 10<sup>6</sup> particles/m<sup>3</sup> for 5 min of UV exposure, to 163.2 × 10<sup>6</sup> particles/m<sup>3</sup> for 15 min of UV exposure, for toluene concentrations in the range of 55 to 85 mg/m<sup>3</sup>. Particle formation was found to increase at a relative humidity of approximately 20% and higher. Variations in the initial number of particles present did not appear to have a significant effect on the particle formation, suggesting that nucleation was not a controlling factor under these conditions. However, tests in a commercial environment at much lower VOC concentrations and lower UV fluence rates showed no detectable PM2.5 formation, indicating that SOA formation during the intermittent use of germicidal UV may not significantly affect indoor air quality under normal conditions. |
| first_indexed | 2024-04-11T12:16:49Z |
| format | Article |
| id | doaj.art-1c80954e052044e8a32b293c1a4cfcf9 |
| institution | Directory Open Access Journal |
| issn | 2076-3298 |
| language | English |
| last_indexed | 2024-04-11T12:16:49Z |
| publishDate | 2019-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Environments |
| spelling | doaj.art-1c80954e052044e8a32b293c1a4cfcf92022-12-22T04:24:16ZengMDPI AGEnvironments2076-32982019-01-01621710.3390/environments6020017environments6020017Formation of Secondary Organic Aerosols by Germicidal Ultraviolet LightEureka Choi0Zhongchao Tan1William A. Anderson2Department of Chemical Engineering, University of Waterloo, Waterloo, ON N2L 3G1, CanadaDepartment of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON N2L 3G1, CanadaDepartment of Chemical Engineering, University of Waterloo, Waterloo, ON N2L 3G1, CanadaUltraviolet (UV) light with a wavelength of 254 nm is known to be germicidal, and thus has been increasingly employed as a method of disinfection for indoor environments. Solar UV wavelengths (300 to 400 nm) are known to initiate the formation of secondary organic aerosol (SOA) particles from the photo-oxidation of volatile organic compounds (VOC) in the atmosphere, but germicidal wavelengths have not been extensively studied for indoor environments. In this work, toluene was exposed to 254 nm UV light in a laboratory photoreactor while varying the conditions of the air, the duration of UV exposure, and the duration of post-UV time. The number of particles formed in the fine particulate matter (PM2.5) size range was measured, and significant levels of particle formation were observed for UV exposure periods of as short as 5 min. The particle formation ranged from 2.4 × 10<sup>6</sup> particles/m<sup>3</sup> for 5 min of UV exposure, to 163.2 × 10<sup>6</sup> particles/m<sup>3</sup> for 15 min of UV exposure, for toluene concentrations in the range of 55 to 85 mg/m<sup>3</sup>. Particle formation was found to increase at a relative humidity of approximately 20% and higher. Variations in the initial number of particles present did not appear to have a significant effect on the particle formation, suggesting that nucleation was not a controlling factor under these conditions. However, tests in a commercial environment at much lower VOC concentrations and lower UV fluence rates showed no detectable PM2.5 formation, indicating that SOA formation during the intermittent use of germicidal UV may not significantly affect indoor air quality under normal conditions.https://www.mdpi.com/2076-3298/6/2/17fine particulatePM2.5UV disinfectionindoor air qualitytoluene |
| spellingShingle | Eureka Choi Zhongchao Tan William A. Anderson Formation of Secondary Organic Aerosols by Germicidal Ultraviolet Light Environments fine particulate PM2.5 UV disinfection indoor air quality toluene |
| title | Formation of Secondary Organic Aerosols by Germicidal Ultraviolet Light |
| title_full | Formation of Secondary Organic Aerosols by Germicidal Ultraviolet Light |
| title_fullStr | Formation of Secondary Organic Aerosols by Germicidal Ultraviolet Light |
| title_full_unstemmed | Formation of Secondary Organic Aerosols by Germicidal Ultraviolet Light |
| title_short | Formation of Secondary Organic Aerosols by Germicidal Ultraviolet Light |
| title_sort | formation of secondary organic aerosols by germicidal ultraviolet light |
| topic | fine particulate PM2.5 UV disinfection indoor air quality toluene |
| url | https://www.mdpi.com/2076-3298/6/2/17 |
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