A Word About Disinfectants
7/13/2020
During these times of COVID-19 various health organizations are requesting that surfaces in public places and other common areas, such as buses, libraries, restaurants, etc., are properly cleaned and disinfected. While this may seem simple enough, many of us do not understand that the act of disinfecting encompasses a specific protocol. The fact is, there is a term associated with this process, for which public health officials – for some reason – have not announced with the clarity and concerted effort for which is necessary. And that term is, “contact time.” Contact time is defined as the time – typically expressed in minutes – that a disinfectant is in direct contact with a specific surface or item to be disinfected. For surface disinfection, this period is determined by the application to the surface until complete drying has occurred.
Therefore, for a disinfectant to work as intended, it needs to keep the surface of concern wet for the specific contact time as listed on the label (or as indicted per the manufacturer’s recommendation – typically available through a google search). This means that when we apply a disinfectant, by simply spraying and wiping a surface and allowing the disinfectant to dry in a few seconds, chances are the car seat, restaurant table or computer screen or keypad, still has infectious germs – and that includes the residue from our latest concern – COVID-19 virus.
Here are a few products with their respective contact times:
- Pine-Sol – 10 minutes
- Sporicidin spray and towelettes – 5 minutes
- Sani-Cloth Germicidal disposable cloth – 3 minutes
- Lysol disinfectant spray – 2 minutes
As these products’ contact times suggest, proper disinfection just doesn’t happen by merely wiping down a surface. We need to make sure the surface remains wet for the entire duration of the products’ contact time. And that may mean we need to continue to spray the surface for a few minutes; thus, ensuring the surface remains moist.
In addition to disinfectants, hand sanitizers have become popular as heath officials have been recommending that we wash our hands frequently throughout the day. Due to much of our field work being conducted in remote locations, soap and running warm water may not be readily available. Therefore, hand sanitizers are used.
Probably most of us are unaware that many hand sanitizers are flammable. A quick review of a popular product, PURELL® Advanced Sanitizer Gel (made by GOJO Industries) Safety Data Sheet (SDS), shows this material has a flash point of 24°C (75.2°F). This is the temperature when in close contact with an open flame, the material can combust. This is due to the main ingredients being ethyl alcohol (50% – 70%) and isopropyl alcohol (1%-5%). Meanwhile the SDS lists the autoignition temperature (temperature at which a material may combust without the assistance of an open flame) as “Not Determined.” However, a search through scientific literature shows that ethyl alcohol has an autoignition temperature of 685°F, while isopropyl alcohol is listed as 750° F. Reaching these temperatures during normal field conditions – even if left in a vehicle in hot, sunny weather – is not a likely scenario.
While it seems to be a far-fetched assumption that a single bottle of hand sanitizers would present a serious fire hazard, it would be appropriate to store these materials in a secluded location, away from ignition sources and quantities of combustibles (i.e. stacks of papers) as well as oxidizers (compressed O2, hydrogen peroxide, chlorine and acids). While flammable storage cabinets are not required for quantities of less than 25 gallons of total flammable materials in a single location, best practice suggests keeping such items – in this case, sanitizers – separate from other chemicals and away from open flames and direct sunlight.
And while PURELL sanitizer is only one product used to keep our hands clean during these times of infectious disease transmission, many other products are available that have their own unique properties. That is one good reason for all of us to take the time and review a products’ SDS – specifically Section 9 (Chemical and Physical Properties) to determine such characteristics as flash points, autoignition temperatures as well as incompatibles. If you need assistance, please contact me. I am always happy to help!
Nobody can hurt me without my permission
Mahatma Gandhi