HYDROXYL RADICALS FOR FIRE RESTORATION: Do They Work? Are They Safe?
Michael A. Pinto, CSP, CMP
David A. Batts
Wonder Makers Environmental
(In conjunction with Odorox Hydroxyl Group October 2015)
This is Part Two of a Wonder Makers Environmental restoration industry project to evaluate the safety of post-fire environments and the potential risk to restoration contractors and others present in these environments, as well as the effect that Odorox hydroxyl generators may have with respect to the safety of these environments. In Part One, after an extensive evaluation of existing literature conducted by Wonder Makers, it was determined that there are potential risks due to the uncertainty of the types and quantities of volatile organic compounds (VOCs) present after a fire. This Part Two report explains the methodology and results of an experiment done to assist the restoration industry in determining the effect of hydroxyl radicals when used as part of fire restoration.
The study involved the construction of a small room finished to represent a standard residential or commercial environment. A controlled fire was ignited in the test room and fed with standard household components such as Romex wire, painted drywall, plastic switch plates, Styrofoam, etc. The room was sealed so that the fire was extinguished by lack of oxygen. Throughout the test, no ventilation was provided and the source material was not removed to simulate a “worst case” scenario. The study was designed to ensure that any changes in the environment were the result of the Odorox hydroxyl generator.
Air samples to measure the specific types and quantities of VOCs present were collected immediately following the extinguishment of the fire. The first sample was collected without the hydroxyl generator being activated to act as a baseline for chemicals in the room. A series of samples were then collected after the hydroxyl generator was turned on. A slide arrangement was set up to allow the sample collection pump to be put into and taken out of the test chamber without having to unseal the room. The samples were analyzed by Prism Analytical Technologies, Inc. (PATI), an independent laboratory that specializes in industrial and environmental air quality.
The Oasis+ model of hydroxyl generators was used for this study and provided by the Odorox Hydroxyl Group. The hydroxyl generator ran during the study with the fan setting on high and the generator setting on low. The low setting was selected because of the size of the test room.
The sample results show a nearly constant reduction in total VOCs (TVOCs) from 48,000 nanograms per liter of air (ng/L) immediately after the fire, to 14,000 ng/L two hours after the hydroxyl generator was turned on, to 2,600 ng/L eight hours after the generator was turned on, to 1,600 ng/L five days after the burn.
Over the course of the test period the types of VOCs recovered varied considerably. Specifically, the data showed that over time the more complex chemical molecules were being changed through chemical reactions into simpler compounds. The study confirms the science provided by the manufacturer that hydroxyls and other radicals eliminate odors and reduce VOCs by breaking down their chemical structures. The levels of individual VOCs in this study, including the intermediate or new compounds formed during the breakdown of VOCs and odors, were well below the permissible exposure levels (PEL) published by OSHA. The study would suggest that the Odorox hydroxyl generator makes the work environment healthier for restoration contractors by reducing the TVOCs after a fire.
The test data matched with the visual and olfactory results with one major exception. The strength and pungency of the smoke odors evaluated by the testers decreased in the first two hours after the hydroxyl generator was turned on. However, over the next six hours, both the strength and pungency of the odors increased before slowly tapering down over the next three days. After five days, without source removal or ventilation, the odor was eliminated and the room smelled fresh. It was also noted that the visible residue that had been observed on the walls of the test chamber had dissipated almost completely.
Wonder Makers Environmental was contacted by Odorox Hydroxyl Group to assist them in providing relevant information to the restoration industry regarding the air quality of post-fire environments. Odorox Hydroxyl Group was also interested in determining if there were any potential risks to restoration contractors when working in such situations. In response, Wonder Makers Environmental suggested a two-part approach. It was recommended that the initial phase of the project be a review of existing literature related to indoor air quality (IAQ) and the risks associated with working in structures that have suffered from fire and smoke damage.
The goal of the first part of the research was to answer important questions about the types and quantities of residual contaminants that may be present in structures at the time that restoration work is undertaken. Specifically, given that smoke odor is often present and addressed
throughout the restoration process, the research paper was suggested to answer relevant questions such as:
- Does the available information suggest that certain harmful contaminants or intermediate compounds are typically present in a fire-damaged structure?
- Is there any research that suggests that environments subjected to fire restoration are generally safe during the various stages of restoration work, or does it suggest that most are potentially unsafe?
- Understanding that every fire is different, and because it always makes sense to err on the side of safety, are there certain types of fires or time periods after fires that are more dangerous?
- Is there any consensus in the current body of knowledge regarding the use of personal protective equipment during the restoration of fire-damaged buildings—especially during the initial cleaning phases?
- Is the risk to restoration workers and the utilization of personal protective equipment related to specific cleaning methods used during remediation?
As such, an extensive literature review was undertaken to determine the types and levels of contaminants that were present in a building following a fire loss (see the white paper completed in April 2015 entitled Understanding the Hazards of Fire Residue Encountered During the Restoration Process, attached as Appendix D). That review of currently available literature uncovered significant research regarding the types of contaminants that are produced during building fires, as well as the type and extent of airborne and surface contaminants that are produced in such conflagrations. A wide variety of noxious materials were identified from multiple studies, with the consistent warning that attempts to fully characterize hazards associated with fire losses are inherently limited compared to the vast array of products that can be impacted by fire and the individual progression that each structure fire takes.
Identifying the large variety of hazardous products produced during a structure fire (including aldehydes, esters, halogenated alcohols, hydrocarbons, nitro-nitriles, ketones, aromatics, sulfides, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, dioxins, etc.) led to the recommendation that personal protective equipment should be utilized by restoration professionals working on such projects.
Despite the thoroughness of the literature review, the study showed that there is little current research related to reducing the impact of airborne contaminants in such buildings by the use of hydroxyl generators. As such, testing in actual or simulated fire conditions was recommended as a follow-up to the initial research. An important aspect of the testing was to determine if the “cascade effect” discussed by the manufacturers of the generators as an aspect of the chemical oxidation process for the contaminant/odor reduction process actually diminishes the hazardous
compounds. It was also designed to determine whether the use of a hydroxyl generator puts restoration workers at any further risk.
Using the information obtained from the Part One study, Wonder Makers designed and conducted a second study to provide further information for the industry. The goal was to conduct a “practical science” study to evaluate the use of the Odorox hydroxyl technology and the possible impact it has in post-fire environments. In this case, the project involved the construction of a simulated finished interior space that was contaminated with fire/smoke byproducts. Numerous samples of VOCs were collected from the fire-damaged space over time in order to gauge the impact that a hydroxyl generator has on a real-world post-fire environment.