Odorox Decomposition

Odorox® Decomposition of Tobacco Smoke Chemicals


Smoke from a burning cigarette is a concentrated aerosol of liquid particles suspended in an atmosphere consisting mainly of nitrogen, oxygen, carbon monoxide and carbon dioxide (Guerin 1980, p. 201). Exhaled, second hand smoke contains predominantly volatile organic chemicals. Particulates 0.3 microns and larger can be removed from smoke by filtration through glass fiber filters. Within the remaining fine particulates and gas are over 4,000 volatile organic compounds (Guerin 1980). Of this massive number of compounds, 70 have confirmed carcinogenic activity in humans, and many more are suspected carcinogens.1

Odorox® Decomposition of Tobacco Smoke Chemicals

The main volatile organic chemicals in tobacco smoke include acetaldehyde, methane, hydrogen cyanide, nitric acid, acetone, acrolein, ammonia, methanol, hydrogen sulfide, hydrocarbons, nitrosamines, carbonyl compounds (Borgerding and Klus 2005; Rodgman and Perfetti 2009), aromatic amines (Patrianakos and Hoffmann 1979), nicotine (Rickert et al. 1984; Pakhale et al. 1997), pyridine (Johnson et al. 1973b; Brunnemann et al. 1978; Sakuma et al. 1984), 3-butadiene, acrolein, isoprene, benzene, and toluene (Brunnemann et al. 1990). Constituents in the particulate phase include carboxylic acids, phenols, water, humectants, nicotine, terpenoids, paraffin waxes, nitrosamines, polyaromatic hydrocarbons (PAHs), and catechols. Spincer and Chard (1971) found formaldehyde in both the particulate and gas phases. The PAHs in the gas phase were only one percent of total PAHs. Odorox® hydroxyls react with and decomposes all of these chemicals.

An average of two million atmospheric hydroxyl radicals (hydroxyls) per cubic centimeter are continuously produced by the action of the sun’s ultra violet (UV) energy on oxygen and water vapor in our atmosphere. Hydroxyls are the main driving force behind the daytime reactions with volatile organic and inorganic gases in the troposphere and decompose most natural and man-made pollutants including greenhouse gases like methane and ozone. Atmospheric hydroxyls are also proven to kill bacteria, virus, and mold because they are able to react with and decompose the chemicals that constitute the cell membranes. Atmospheric hydroxyls are a critical component of nature’s dynamic ability to provide environments that are free of pathogens and harmful chemicals.

Outdoor hydroxyls are very short-lived, however, and do not survive long enough to cleanse indoor air. Increasingly our homes, work places, indoor recreational and travel environments have chronic, unhealthy levels of Volatile Organic Compounds (VOC’s) and pathogens, in spite of ventilation. This is particularly true of indoor environment where smoking is permitted. Odorox® sanitizing systems were developed to cleanse indoor environments and decompose the vast majority of organic chemicals in air and of surfaces, including the surfaces of particulates.


There is extensive data in the atmospheric chemical literature about how hydroxyls are generated and react to sanitize. The efficacy and safety of the Odorox® atmospheric hydroxyl purifying systems has been validated by extensive third party chemical, engineering, microbiological and toxicology data and, for selected models, by the Food and Drug Administration (FDA). When used as directed, Odorox® systems are proven to release a continuous steam of hydroxyls and secondary oxidants that restore nature’s balance indoors.

Odorox® systems utilize multiple wavelength UV energy to generate effective concentrations of free hydroxyl radicals within the photolysis chamber. These hydroxyls react rapidly with VOCs passing through the chamber and initiate the formation of a series of secondary organic oxidants that are propagated throughout the treatment space, all of which contribute to air cleansing. HGI calls the formation of these secondary organic oxidants the “cascade” effect. In order to validate the proposed mode of action of Odorox® sanitizing systems, HGI commissioned studies at the Lovelace Respiratory Research Institute (LRRI) to independently measure the rate of hydroxyl radical formation and reactivity with VOCs by an Odorox® Boss™ system. They verified that the levels of hydroxyls produced were similar to those found in nature and that they reacted with airborne VOC’s and other gases like nitric oxide, formaldehyde and ozone. Measured reaction rates are incredibly fast, on the order of 20 to 50 milliseconds. These studies have been further analyzed and validated by a leading industry expert in atmospheric hydroxyl radical chemistry, Dr. David Crosley.

Atmospheric hydroxyls are the perfect sanitizing agent. They react with a broader range of chemicals and are over one million times faster than ozone, bleach or other sanitizing agents. They react principally by removing a hydrogen atom and forming an organic radical that is subsequently decomposed by continued oxidation. The organic radicals formed set up a complex chain reaction of many radical by-products. These by-products include secondary oxidants like peroxy and oxy radicals that are themselves good sanitizing and deodorizing agents as they are more stable than the original hydroxyl radical and able to penetrate large volumes of air. As in nature, the individual steps grow exponentially in complexity. The net result is that organic compounds are reduced in size and oxidized until they eventually form carbon dioxide, oxygen and water. As long as the system is running, the chain reactions persist and maintain nature’s balance indoors.

As in nature, ozone is produced as part of the UV irradiation process in air. Once formed it is decomposed by a variety of pathways including UV energy decomposition, reaction with VOC’s and reaction with hydroxyls. Although hydroxyls will react with most VOC‘s before ozone can, ozone is an important part of the air cleaning process because of its ability to react with a special type of VOC that contains a carbon-carbon double bond - called an alkene - to generate hydroxyl radicals throughout the treatment space. Tobacco smoke generates alkenes called terpenes. Alkenes are also produced by humans, who respire parts-per-billion (ppb) levels of an alkene called isoprene. In a crowded room,
isoprene levels can reach the low parts-per-million (ppm) levels.


As a category, the FDA and other regulatory agencies do not regulate or require pre-market approval for UV air and surface cleaning devices used in residential and commercial applications as they irradiate ambient air and sanitize in a manner similar to that found in nature. The FDA does require 510(k) premarket approval of UV sanitizing systems for use in medical facilities. The FDA reviewed and approved the Odorox® MDU/Rx™ system for use in occupied spaces in medical facilities (510(k) #133800). The FDA does not regulate UV sanitizing systems that are integrated with heating and ventilation systems in commercial or medical facilities, such as the Odorox® IDU™ Induct and MVP™ series systems. These systems have the capacity to safely treat millions of cubic feet of air.

Regulatory agencies such as the Occupational Safety and Health Administration (OSHA) do monitor the chemicals that can be generated from UV sanitizing systems. Acetaldehyde and formaldehyde can build up as larger VOC’s are decomposed by hydroxyls. They are the last products produced before complete oxidation to carbon dioxide and water. A device that produces sufficient concentrations of hydroxyl radicals will keep the steady state levels of these terminal oxidation products near background levels as these small VOC’s react with hydroxyl radicals more rapidly than larger VOC’s. This is what happens in nature. Studies at LRRI and Columbia Analytical Laboratories (Sunnyvale, CA) confirmed that HGI systems produce sufficiently high concentrations of hydroxyls to efficiently decompose ambient VOC’s and their by-products so that formaldehyde and acetaldehyde rapidly reached low steady state levels that remained near ambient baseline levels of 10 to 15 ppb for extended periods.

OSHA requires that indoor ozone levels are below 100 ppb for safe, long-exposure. Typical natural ozone levels range from 20 to 60 ppb. HGI technology maintains these same natural levels through the use of customized optics, system design optimization, recommended ventilation practices and machine selection for given volumes of treated air. For its larger industrial systems, like the MVP™ series systems (such as MVP14™, MVP24™ and MVP48™ systems), HGI has integrated real-time interactive process controls so that oxidant levels can be accessed remotely and measured continuously, enabling machine settings to be adjusted automatically to maintain whatever oxidant levels that are


Researchers such as Weschler and Shields have speculated on the potential health hazards of the oxidation products resulting from use of UV hydroxyl radical air sanitization devices indoors. At HGI’s request, the National Institute of Environmental Health Sciences (NIEHS) searched the National Institutes of Health (NIH) files, PubMed and the National Library of Medicine and “cannot find any hard science or research indicating that hydroxyl radical generation is harmful to human health. That applies to both atmospheric and man-made generation” (Colleen Chandler, NIEHS Office of Communications and Public Liaison, 08-05-2010).

Further, at HGI’s request, the Centers for Disease Control and Prevention (CDC), FDA, OSHA and NIH researched their databases and did not find any data indicating that hydroxyls were unsafe. None of these agencies indicated that their approval was required for commercial use. It is not likely that this will change as hydroxyl radical sanitizing systems generate levels of by-products that match those produced by the sun outdoors.

Although no adverse effect from the use of UV hydroxyl generators have ever been reported, there have been no toxicology studies to verify this. Therefore HGI conducted a comprehensive toxicology study with an industry leading clinical contract research company, Comparative Biosciences Incorporated (Sunnyvale, CA). This study involved the use of forty (40) test rats and twenty (20) control rats and was conducted in compliance with the US Food and Drug Administration’s Good Laboratory Practices (GLP) regulations (21 CFR Part 58). Extensive data was collected including behavioral, physiological, neurological, hematology, clinical chemical analysis, neurology, ophthalmology, and gross histopathology. The study results indicated that the test animals tolerated the exposure well with no abnormal clinical observations. There were no histopathology /cytopothology (cellular level) differences between the control rats and the exposed rats. During analysis, specific attention was paid to the skin, eyes, nasal turbinates, larynx/pharynx, and respiratory system. There were no changes in these organs and they appeared to be within normal limits in both the control and treated animals.

In conclusion, HGI Odorox® systems have the capacity to safely decompose even high ppm levels of volatile organic chemicals generated by indoor smoking in air and on surfaces, rendering the environment safe for occupancy.

HGI Industries, Inc.
Scientific Advisory Board Publication

Dr. Connie Araps
Chairman HGI Scientific Advisory Board


1. How Tobacco Smoke Causes Disease: The Biology and Behavioral Basis for Smoking-Attributable Disease: A Report of the Surgeon General. Centers for Disease Control and Prevention (US); National Center for Chronic Disease Prevention and Health Promotion (US); Office on Smoking and Health (US). Atlanta (GA): Centers for Disease Control and Prevention (US); 2010. https://www.ncbi.nlm.nih.gov/books/NBK53014/

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2. D. E. Heard, “Analytical Techniques for Atmospheric Measurement”, Blackwell Publishing, 2006
– professor at the University of Leeds, UK) and references cited therein.

3. R. Atkinson, “Kinetics and Mechanisms of the Gas-Phase Reactions of the Hydroxyl radials with Organic Compounds”, Journal of Physical and Chemical Reference Data, Monograph No.1,1989.

4. J. Rosenthal, “Study of Photocatalytic Oxidation Raises Questions About Formaldehyde as a Byproduct in Indoor Air”, Lawrence Berkeley National Laboratory, December 19, 2008.

5. A. T. Hodgson, D. P. Sullivan and W. J. Fisk, “Evaluation of Ultraviolet Photocatalytic Oxidation for Indoor Air Applications - Conversion of Volatile Organic Compounds at Low PPB Concentrations”, LBNL-58936, 2008.

6. C. Weschler and H. Shields, Environmental Science and Technology, “Production of the Hydroxyl Radical in Indoor Air”, Vol. 30, No. 11, 3250-3258, 1196 and references cited therein.
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