Part 2 – Environment Safety
The first installment of this series (Part 1) on laboratory safety amidst the Covid-19 crisis dealt with enhancing your personal body protection. The focus was on clothing and gear designed to minimize your risk of exposure. It was stated that, while much is unknown, and we are still learning about this new virus, studies of like viruses show that it can remain active for days on surfaces such as workstation countertops, microtomes, microscopes, and many other equipment surfaces. What ‘is’ known about this virus is that it has multiple diverse and effective modes of transmission ranging from direct hand-to-hand contact,
surface to hand/skin contact, and aerosol particles from coughing, sneezing, and even simple speaking. With respect to the latter method (aerosol), a recent study published in the New England Journal of Medicine (Meselson, M.) looked at the size and amount of aerosol droplets emitted during normal human speech. Using laser light visualization, the study was able to demonstrate that an abundance of fluid droplets are emitted when speaking, and while the larger of these droplets fall to the floor or more immediately a surface (such as mentioned above), smaller droplets can dehydrate
and remain as “droplet nuclei” in aerosol form. The image to the right demonstrates the visual range of size and quantity of oral spray when speaking. They become non-visible infectious particles which can be breathed in by a new host. Further, inhaled droplets have multiple sites of deposition in a person. One area is the nasal passages and deep oral cavity. This explains the method of COVID-19 testing where swabs are used by deep insertion into the nasal cavity to collect a specimen. The second and more alarming site of deposition described in the article is that droplets can penetrate deep into the lungs and rest in the alveoli. This is the primary site of infection where the virus manifests into a full-blown respiratory disease. The information above substantiates two factors discussed in Part 1 of this series:
- The need for all lab workers to wear masks while on duty
- Approximately 25% of people that test positive for COVID-19 are asymptomatic, meaning they seem fine but are potentially spreading the virus in their work environment just from simply talking to others
When considering ‘environmental safety’ in your workplace, and the fact that the type of infectious spray mentioned above can be resting and lingering on surfaces, all areas that you encounter in your daily work should be considered suspect and potential resting sites for active virus. Coronavirus is known to remain active for 2-5 days and potentially even longer. The question then becomes, how do I become proactive about enhancing my safety in my environment. Making a personal assessment of all areas of direct contact is the beginning, followed by using the knowledge we have of how like viruses are contained or disinfected.
Even though in common language, sanitizers and disinfectants are often used synonymously, they are actually two distinct chemicals with different effects on microorganisms. By definition, sanitizers reduce the number of organisms on a surface, but they are not as effective at killing and totally eradicating the agent. With pathogens, there is typically a certain number of germ load that you need to come into contact with on a surface to contract the disease Sanitizers lower the total germ load on a surface and help minimize the potential of infection to a host. Also, sanitizers work almost immediately in their effect on organisms, as quickly as one minute. There are several hand sanitizers available, but the safest and most convenient are the 62%-70% alcohol-based types. Unfortunately, the high alcohol content results in it evaporating fairly quickly and may not be as effective for long-term protection. Sanitizers are quick and simple but not as effective as soap and water in long-term protection. They should not be considered as a first choice in cleaning surfaces.
Disinfectants are much stronger in their chemistry and are designed for 100% killing of microbes. They are designed almost specifically for cleaning interior and exterior surfaces, and because of their stronger chemical nature, they are generally used in weaker dilute formulas. Disinfectants take longer to be completely effective, as much as 10 minutes, but they kill a wider variety of organisms than sanitizers and have a longer lasting effect on surfaces. Interestingly alcohols in high concentrations are considered to be an effective basic disinfectant, but because of evaporation issues, other stronger chemical disinfectants are much more efficient.
Within the laboratory environment, it is not advisable to use strong industrial cleaners and disinfectants, but one of the safest disinfectants to use on common countertops and equipment surfaces is 70% alcohol. This should be used regularly to wipe down microtomes and your workstations at the start and the end of your daily shift, and also other equipment commonly used such as microscopes, slide stainers, instrument keyboards, slide boxes, etc. Another disinfectant that is even more efficient is dilute sodium hypochlorite (bleach) at a 0.1% dilution level. This
disinfectant has a longer lasting effect on surfaces but is more caustic in touch and smell than alcohols. It ‘is not’ advisable to use this on most laboratory equipment unless specifically noted by the manufacturer. It is particularly good for end of the day cleaning of countertop surfaces, sink or rinse stations, and other hard surface areas. Both disinfectants mentioned can be applied by using 4×4 gauze pads or some other form of cleaning pad and wiping back and forth over the surface at least 3-4 times. Always wear gloves when using these to clean equipment or surfaces. The five (5) basic steps to infection control cleaning of surfaces is:
- PPE – Gloves, mask, labcoat or apron
- Cleaning – wipe down or wash dirt, dust, or excess debris
- Disinfect – use gauze and disinfectant liquid or spray. Discard gauze in bio-hazard container
- Dry – allow surface to dry
- PPE – Discard gloves and gauze in bio-hazard containers
Common areas and personal items must be included in any discussion of environmental safety. Most laboratories have implemented some form of social distancing or total capacity restrictions on common areas such as break rooms, conference/meeting rooms, etc. When using these areas, it is advisable to use some form of sanitizers or disinfectant on any surfaces (tables, chairs, refrigerator handles, etc.) you use when
use when you enter. In the lab there are common areas that are used by multiple staff members such as computer workstations, keyboards, file cabinets, etc. These areas are potential transmission sites from one person to another and must be disinfected with each new user. With respect to personal items such as cell phones, glasses, personal pens; all of these are potential transport stations where bacteria or viral contagions can rest and be carried out of the lab even to your home. Laboratories typically have some form of policy against using personal cell phones in the work environment, but most workers use their cell phones multiple times during the day while at work, even if just on breaks or lunches. Any item that you have out exposed in the lab or hospital environment has the potential to receive and transport microorganisms. Therefore, consideration must be made to monitor and disinfect these items periodically during the day..
Finally, some form of infectious control warning should be placed at all entrance doors to the lab instructing those who enter to follow specific infection control precautions. A similar posting with the appropriate instructions should be placed in all common areas frequently used in the lab (sinks, staining areas/equipment, lab phones, etc.). The image to the right is an example of what could be used at entrances.
This article lists just some of the basic considerations in lab environmental safety with respect to infection control. Because of the unknown aspect of COVID-19 virus there is no absolute fool-proof plan for 100% protection. Confronting and eliminating this virus in our workplaces will require adopting enhanced methods such as these and more. Please continue to follow all CDC guidelines, your facility’s internal lab policies, and personal diligence to keep your areas clean and contagion-free. The ‘new’ normal in the lab must become a heightened sensitivity in all areas
- Meselson Matthew. (2020) Droplets and Aerosols in the Transmission of SARS-CoV-2. N Engl J Med
DOI: 10.1056/NEJMc2009324 [Anfinrud, P., Stadnytskyi, V., Bax, C., Bax, A.]
- https://www.webm d.com/lung/how-long-covid-19-lives-on-surfaces
- Healthline, ‘Using 70% Alcohol to Clean’, www.bing.com
- www.walmart.ca, Alcohol Cleaning Cloths-Cell phones