Next Article in Journal
Geoheritage in Deltaic Environments: Classification Notes, Case Example, and Geopark Implication
Previous Article in Journal
Biogas Production by Co-Digestion of Canteen Food Waste and Domestic Wastewater under Organic Loading Rate and Temperature Optimization
Previous Article in Special Issue
Vinasse Treatment within the Sugarcane-Ethanol Industry Using Ozone Combined with Anaerobic and Aerobic Microbial Processes
Article Menu
Issue 2 (February) cover image

Export Article

Open AccessArticle

Formation of Secondary Organic Aerosols by Germicidal Ultraviolet Light

Department of Chemical Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada
Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada
Author to whom correspondence should be addressed.
Environments 2019, 6(2), 17;
Received: 30 November 2018 / Revised: 18 January 2019 / Accepted: 27 January 2019 / Published: 31 January 2019
(This article belongs to the Special Issue Advanced Oxidation Applications)
PDF [1707 KB, uploaded 31 January 2019]


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 × 106 particles/m3 for 5 min of UV exposure, to 163.2 × 106 particles/m3 for 15 min of UV exposure, for toluene concentrations in the range of 55 to 85 mg/m3. 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. View Full-Text
Keywords: fine particulate; PM2.5; UV disinfection; indoor air quality; toluene fine particulate; PM2.5; UV disinfection; indoor air quality; toluene

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Choi, E.; Tan, Z.; Anderson, W.A. Formation of Secondary Organic Aerosols by Germicidal Ultraviolet Light. Environments 2019, 6, 17.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Environments EISSN 2076-3298 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top