Environmental Hygiene for COVID-19: It’s All About the Mask

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the infectious agent presumed to cause COVID-19 symptoms, is spread person to person or indirectly via respiratory droplets and aerosols through two mechanisms: (1) inhalation, or (2) fomite mediated transmission (i.e., face touching following contact with a contaminated surface) (WHO 2020b). Currently, there is no widely recommended pharmaceutical treatment or preventative vaccine; therefore, the primary means of containment of COVID-19 focuses on nonpharmaceutical interventions (NPIs). Recommended NPIs include both engineering solutions, such as improved building ventilation, as well as behavioral solutions such as physical distancing (also known as social distancing), covering coughs and sneezes, and regular hand washing (Chu et al. 2020).

Personal protective equipment (PPE), such as N95 respirators, may be used to prevent inhalation of respiratory droplets and aerosols (FDA 2020). To be effective, PPE requires adherence to strict protocols (i.e., removing excess facial hair and performing fit tests to ensure a tight seal). For a variety of reasons—including limited supplies, lack of training, and low likelihood for exposure—N95 respirators are not recommended for public use to contain COVID-19 (CDC 2020c). Instead, the “vampire cough” (i.e., partially covering the mouth and nose by placing the face in the crook of the arm) is typically recommended to reduce the spread of respiratory droplets.

The regular use of a mask is similar to a continuous vampire cough position and helps to reduce the production of respiratory droplets from a presumptive infected individual. Furthermore, scientific evidence suggests that the regular use of a mask may provide a statistically insignificant but real level of personal protection via inhalation exposure for an uninfected individual (e.g., Cowling et al. 2008; Smith and Watson 2020). Therefore, health care professionals recommend individuals wear masks, especially when physical distancing cannot be readily achieved.

The recommendation for widespread use of masks must be considered in light of existing guiding principles for professional practice. For example, health care professionals adhere to the Hippocratic oath, which includes the promise “to abstain from doing harm” (Edelstein 1943). Similarly, environmental engineers are familiar with the precautionary principle, which calls for pause and scientific study before widespread adoption of innovations. Therefore, both health care professionals and environmental engineers have an obligation to ask questions about the current recommendation to wear masks. To be very clear, the authors are NOT arguing against current recommendations on the use of masks, but rather we are raising questions for professionals to urgently consider.

Who should be exempt from mask wearing (e.g., everyone under 2 years of age, anyone who has trouble breathing, anyone who is unable to remove the mask without assistance), and how should we educate the public about the necessity of these exemptions without increasing stigma?

Is all mask wearing equally effective (e.g., loose versus tight fitting over the mouth and/or the nose; surgical masks, trilayer, or cotton-only cloth masks, gaiters, or face shields)?

Should the behavior change of mask wearing be temporary, just until a vaccine is readily available and taken up by much of the world?

What if mask wearing becomes more permanent in the US (much like in some parts of Asia)? A problem is that public US systems are based on uncovered faces (e.g., facial recognition to prevent crime and other applications). If we start using masks for much of the year, we’ll need to throw away and start again with these and other technologies. So, once a public health behavior change is adopted, will it become permanent, even if it was originally intended as a temporary measure?

How does mask wearing impact mental health (of users and observers)? For example, the Centers for Disease Control and Prevention (CDC) recognizes that mask wearing has mental health implications such as creating trigger events for those who have been assaulted or abused (by a perpetrator who had their faces covered). And although we are not aware of any current studies, it would not be surprising that widespread use of masks may have an impact similar to Zoom fatigue (Wiederhold 2020); hearing a voice without seeing the emotion of a face is not a normal human condition and can produce strain on emotional intelligence—with impacts on mental health.

And, finally, what is the appropriate hygiene for mask wearing (i.e., cleaning and disposal), and how should we educate the public on a cradle-to-cradle approach to a new consumer product?

The US Surgeon General has warned the public about the importance of mask hygiene saying, “You can increase your risk of getting it [COVID-19] by wearing a mask if you are not a health care provider. … Folks who don’t know how to wear them [masks] properly tend to touch their faces a lot and actually can increase the spread of coronavirus” (Howard 2020). The CDC offers guidance to the public on how to wear cloth masks (CDC 2020b), and the World Health Organization (WHO) offers guidance to the public on how to construct and wear trilayer fabric masks composed of a hydrophilic material near the face (i.e., cotton to wick moisture), a filter insert, and a hydrophobic material on the outside (i.e., polyester) (WHO 2020a).

The Occupational Safety and Health Administration (OSHA) offers guidance to protect workers including health care providers as well as janitorial and custodial staff and workers in solid waste and wastewater management (OSHA 2020b). According to OSHA guidance, “most environmental services workers [janitorial and custodial staff] are unlikely to need PPE beyond what they use to protect themselves during routine job tasks” (OSHA 2020a). Similarly, according to OSHA guidance, “There is no evidence to suggest that additional, COVID-19-specific protections are needed for employees involved in wastewater management operations, including those at wastewater treatment facilities” (OSHA 2020c).

Companies specializing in collecting and disposing of regulated substances have offered guidelines for managing COVID-19-contaminated garbage (Stericycle 2020). For environmental engineers, it is important to note that the US Environmental Protect Agency has limited authority in medical waste regulation since the expiration of the 1988 Medical Waste Tracking Act in 1991 (EPA 2020).

While ongoing basic research continues to paint an unclear picture of the effectiveness of various fabric masks to reduce the spread of COVID-19 via inhalation (e.g., Fischer et al. 2020), early results of life-cycle assessments suggest that fabric masks containing resource-intensive cotton may need to be reused multiple times to compete with the lower carbon footprint of the disposal plastics contained in a commercial N95 respirator (Liebsch 2020). The key to reusing fabric masks includes the processes of washing and drying (CDC 2020a), and while the guidance from the CDC provides recommended procedures for washing, there is no mention of disinfecting (i.e., sanitizing reduces the number of germs on surfaces through a combination of washing with soap and water as well as disinfecting with chemicals such as chlorine bleach, alcohol, or quaternary ammonium cation–containing disinfectants commonly known as quats) (CDC 2018). Finally, although practical guidelines for mask hygiene are widely available (e.g., Bennett 2020), there is a paucity of basic research study supporting these rules of thumb.

The response of public health professionals, including environmental engineers, to the COVID-19 pandemic has been heroic. The authors have no doubt that best intentions are guiding recommendations offered to governments by health care providers. Nonetheless, the speed with which masks have been widely deployed globally raises a number of concerns, and in this editorial we raise the point that past experience with hygiene should be considered carefully as we continue to address the COVID-19 pandemic. For example, the use of underwear is ubiquitous, related to personal hygiene, and likely related to health outcomes. As mask wearing becomes ubiquitous, environmental engineers and other public health professionals should consider mask-wearing hygiene as part of the response to the COVID-19 pandemic but with a cautious eye toward unintentional outcomes from widespread mask wearing.

No data, models, or code were generated or used during the study.