cleaning with microfibre mop

Cleaning schools in the age of COVID-19

Schools have the responsibility to prevent and control infectious diseases. The pandemic makes this mission even more imperative
Tuesday, April 7, 2020
By B. Douglas Ford and Keith Sopha

Currently, we are in the midst of a worldwide COVID-19 pandemic, and for the foreseeable future, this will have serious implications for the cleaning of our schools and indeed all public spaces. This pandemic has resulted in considerable morbidity and mortality. As we struggle to deal with COVID-19, we need to ask ourselves, “will we be prepared for the next novel pathogen?” Future pandemics are inevitable; global warming allows novel pathogens to migrate to areas where humans do not have immunity. Ever-increasing human travel for vacations and trade aids their distribution.

Custodians and environmental service managers deal with a variety of pathogens in our schools on a daily basis, as well as frequent outbreaks of influenza, norovirus, and the common cold. Much needs to be done to promote student safety and good health by developing an effective environmental cleaning strategy for routine cleaning and disinfection, as well as dealing with infectious outbreaks in our schools.

The five-second rule

The five-second rule is the belief that if you drop food or candy on the floor and pick it up within five seconds that it is safe to eat it. Let’s imagine you drop a honey-glazed donut on a student desk at the end of the day before scheduled cleaning. You snatch the delicious donut up in five seconds. Should you eat it?

In the study, An Evaluation of Conventional Cleaning and Disinfection and Electrostatic Disinfectant Spraying in K-12 Schools, published in upcoming issue of the Canadian Journal of Infection Control, we tested this rule on uncleaned desks using sticky agar plates that were lightly pressed to desks for five seconds. Student desks in K-12 schools were found to be highly contaminated with viable microbes before cleaning and disinfection. Our study results do not support the five-second rule; the dropped donut will likely be contaminated. If you scrape off the glaze on the side that landed on the desk, is the delicious donut now okay to eat? We will leave that decision up to you.

Researchers have found that student desktops are rife with numerous and various pathogens, such as Streptococcus and Staphylococcus bacteria, and viruses such as influenza and norovirus. While viruses such as influenza, the common cold, and noroviruses can live on desks for several days, bacteria and fungi can live for months. On hard surfaces like desks, the Center for Disease Control (CDC) reports Covid-19 can also survive for several days. These findings highlight the need for effective cleaning and disinfection in our schools. Efficacious cleaning and disinfection would help to prevent the spread of infectious illnesses such as colds, pharyngitis, influenza, intestinal ailments, and COVID-19 amongst students, teachers, and their families and community.

Cleaning and disinfection methods

Effective cleaning and disinfection of classrooms can kill disease causing pathogens and reduce student illness and absenteeism. The CDC and the Public Health Agency of Canada (PHAC) have developed cleaning and disinfection recommendations for COVID-19 (aka SARS-CoV-2) that are similar to recommended practices for controlling other respiratory infections. High touch surfaces, such as light switches, door knobs, tables, washrooms, and desks should be cleaned and disinfected frequently, at least twice a day and when soiled. The CDC recommends cleaning with soap and water and disinfecting with diluted bleach, 70 per cent alcohol, or EPA-registered disinfectants. PHAC recommends disinfection with solutions having a Drug Identification Number (DIN) that are labeled as broad-spectrum virucides.

Conventional environmental cleaning in schools involves manually applying cleaning and disinfection solutions and wiping with cloths. Spray and wipe cleaning and disinfection procedures in schools and healthcare settings may not achieve the desired level of decontamination. Newer technologies such as ready-to-use wipes, ultraviolet light towers, and hydrogen peroxide vapor / spray mist units have improved disinfection of hospital surfaces and may prove to be useful in schools.

The electrostatic spraying of disinfectants is a newer technology that could also be readily used in schools. We conducted an evaluation of this technology in K-12 schools and found that for a single use, the electrostatic sprayer was effective in decreasing viable microbial loads. The electrostatic sprayer sends a negatively charged plume of quaternary ammonium disinfectant that envelopes sprayed objects and can reach locations where pathogens are not readily accessible to manual spray bottle and wiping. It was thought electrostatic disinfectant spraying may be especially beneficial during influenza and other infectious outbreaks to increase the frequency of disinfection. There is the need to conduct further research into the effectiveness of electrostatic spray technology and other newer technologies such as ready-to-use wipes, ultraviolet light towers, and hydrogen peroxide vapor / spray mist units in cleaning and disinfecting our schools.

Present cleaning and disinfection procedures in schools

We asked school custodians about cleaning methods and products they used. In all schools this method was cleaning and disinfecting in one step; referred to as one clean. The conventional cleaning and disinfection practices of school custodians were quite variable. Most schools sprayed and wiped with hydrogen peroxide based solutions; however, one used a quaternary ammonium solution and another school used a bucket based system. Most schools used microfiber cloths while one used rags. Some schools clean the desks at lunch and then place un-wiped chairs on desks at the end of the day, so floors could be cleaned. One school cleaned and disinfected desks only once a week. Meanwhile microbes re-establish themselves on student desks in as little as two days.

In addition to asking custodians about cleaning practices, we observed their work setting. Cleaning carts and housekeeping storage rooms were stocked such that soiled items were found in close proximity to or in contact with clean items. These practices risk cross contamination and negatively impact cleaning and disinfection efforts.

Evidence-based best practices

School administrators and custodial managers have the responsibility to prevent and control infectious diseases in schools and to protect students, teachers, and the public by ensuring the most effective cleaning and disinfection practices are used. The COVID-19 pandemic makes this mission even more imperative. A first step would be to assess pathogen types and levels in schools. Numerous and various locations in classrooms, washrooms, gyms, and school libraries need to be sampled to determine which microbes inhabit our schools and where and at what contamination levels.

The next step would be to rigorously evaluate current cleaning and disinfection practices: Equipment, detergents and disinfectants, cleaning schedules, and staff training. Are present environmental cleaning practices helping students to be safe from infectious diseases? This research initiative, in conjunction with an extensive literature review and lab investigations would aid in the development of a best practices cleaning and disinfection program for schools. A cleaning and disinfection best practices training program for custodians would also need to be developed, evaluated, and implemented.

In Ontario, the Provincial Infectious Diseases Advisory Committee developed an evidence-based best practice document for cleaning and disinfection in healthcare settings. The development of effective and standardized cleaning and disinfection guidelines and standards for schools would have both health and fiscal benefits. Reductions in levels of potentially harmful viruses, bacteria, and fungi in our schools would result in less student illness as well as less infectious diseases in teachers and the general population. Our healthcare system would realize lower financial costs through reductions in environmentally-acquired infections. Standardized cleaning procedures, equipment, and solutions would enable further cost savings from bulk purchasing. It is recommended the Ontario ministries of education and health develop evidence-based best practices for cleaning and disinfection in schools.

B. Douglas Ford is a senior researcher for the Canadian Association of Environmental Management. He can be reached at:

Keith Sopha is president of the Canadian Association of Environmental Management and founder of CleanLearning. He can be reached at:

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