Alcohol-based hand sanitiser fire risk
The current pandemic situation that we are all experiencing has increased exponentially the need and production of hand sanitizers and disinfectants. There are mainly two types of hand sanitizers in the market: alcohol-based (ABHS) and alcohol-free (Fig.1)1.
ABHS products always contain a type of alcohol (isopropanol, ethanol or n-propanol) as the main antiseptic, or a combination of 2 of these, and sometimes combined with other non-alcoholic antiseptic agents2,3. Hydrogen peroxide is also needed to keep the formula spore-free, since alcohol is not effective against them7. The excipients can be glycerine, fragrance and/or colorants depending on the formulations, with the mission of preserving the product, enhance it, or buffer it4. Alcohol-free sanitizer use chemicals with antiseptic properties to exert the antimicrobial effects1, plus the same excipients mentioned before.
ABHS normally contain between 60% and 95% alcohol, and it possesses a broad and immediate activity, since their antimicrobial activity is based on protein denaturation and coagulation3. The highest antimicrobial efficacy can be achieved with ethanol (60% to 85%), isopropanol (60% to 80%), and n-propanol (60% to 80%)3. However, the main drawback of alcohol is that it is a flammable substance3.
In order to get an insight of the potential fire risk that flammable liquids and low-melting substances can pose, we need to look at the flashpoint temperature of the substance in question. This flashpoint is defined as “the minimum temperature at which a flammable substance can be ignited by an open flame”5. In Table 1, we can see the flashpoints of ethanol and propanols. As we can appreciate, the flashpoint is dependent of the active substance’s concentration: the higher the concentration, the lower the flashpoint.
Liquids with a flash-point below 21°C are considered ‘easily flammable’; therefore, looking at Table 1 again, we can see that only formulations with concentrations of 68% ethanol (and above) will be considered easily flammable. Easily flammable iso-propanol will be found at concentrations of 70% alcohol or higher, while in the case of n-propanol, it will be from 82% and higher concentrations. In the flammability test of alcohol-based hand sanitizer by Cavage 20106, 60% alcohol by volume proved to be flammable, as expected, and could be easily ignited. The fire was described to be “coolly, with peak flame temperatures between 500° and 1000°F”, which will correspond to 260° and 538°C, and to gel and liquid hand sanitizer respectively.
Even if ABHS are normally contained in small dispensers and packages, constituting a low fire hazard, the risk increases when formulations mix ethanol with n- or iso-propanol (since the flammability point decreases) and/or when they are transported and stored in big volumes5. All ignition sources, like heat, sparks and flames, must be avoided when stored and, if there is possible flammable vapour accumulating, the room needs adequate exhaust ventilation as well7. Flammable substances must be stored at a good distance from other combustible material and in special fire compartments with self-closing doors. The distance between these and escaping routes must be at least of 8 meters. In order to evaluate these parameters, public facilities and institutions must carry a fire risk assessment, so they can comply with regulations. Workers at these facilities should also be well trained as well, in case of fire emergency.
However, are these rules and premises actually followed?
Brann- og Sikkerhetsrådgivning AS (BSR) was hired by Oxyl Clean AS as a fire technical consultant to assess whether there are fire technical issues related to the use and storage of alcohol-based disinfectant in a selection of shops/shopping centres, and a nursing home in Norway. BSR assessed laws, regulations, and other supplementary guidelines and to what extent these have been followed. The main conclusions after their observations were the following8:
- Whether or not there exists a regulation and a thematic guide on how to handle flammable liquid, it has not had any effect on how the liquid has been handled.
- Although all types of businesses are required to conduct systematic HSE work to detect / identify risk, no significant risk is detected nor has the business implemented measures.
- None of the companies inspected had implemented fire technical constructional measures.
- None of the companies that have answered our questionnaires had implemented organizational measures.
- All inspected companies stored flammable liquid in connection with the evacuation route.
- All inspected companies stored flammable liquid nearby other combustible materials.
- All companies inspected have a high probability that ignition of the flammable liquid can occur due to carelessness or technical faults.
- There is no clear warning that the liquid is so easily ignitable that it can be ignited even by static electricity.
- There is no warning that the liquid is burning with an almost invisible flame, emitting no smoke.
The lack of resources, information and/or training, human error, or even negligence, can lead to a really serious hazard when manipulating and storing big quantities of ABHS. The previous examples are from a well-prepared country like Norway, but what happens in low and middle-income countries, where the high demand of ABHS has lead to local production of these substances? The fire hazard is even higher, as Selam and colleagues9 showed.
Extra precautions are in order and, even if ABHS benefits normally outweigh its risks, there might be some situations in which effective alternatives should be taken into account.
- Jing, J. L. J. et al. Hand Sanitizers: A Review on Formulation Aspects, Adverse Effects, and Regulations. Int. J. Environ. Res. Public Health 17, 3326 (2020).
- Berardi, A. et al. Hand sanitisers amid CoViD-19: A critical review of alcohol-based products on the market and formulation approaches to respond to increasing demand. Int. J. Pharm. 584, 119431 (2020).
- Gold, N. A. & Avva, U. Alcohol Sanitizer. StatPearls (StatPearls Publishing, 2018).
- Todd, E. C. D. et al. Outbreaks where food workers have been implicated in the spread of foodborne disease. Part 10. Alcohol-based antiseptics for hand disinfection and a comparison of their effectiveness with soaps. J. Food Prot. 73, 2128–2140 (2010).
- Rotter, M. L. Arguments for alcoholic hand disinfection. J. Hosp. Infect. 48, S4–S8 (2001).
- Cavage, W. M. Flammability Test of Alcohol-Based Hand Sanitizer. (2010).
- Lyondell Chemical Company. Ethyl Alcohol Handbook. (2015).
- BSR. Initial fire technical evaluation: The handling of flammable disinfectant. (2020).
- Selam, M. N. et al. Increased production of alcohol-based hand rub solution in response to COVID-19 and fire hazard potential: Preparedness of public hospitals in Addis Ababa, Ethiopia. Risk Manag. Healthc. Policy 13, 2507–2513 (2020).