Microbes Weigh on Our Minds

It’s no wonder that homeowners and those in the market for a home are wondering if antimicrobials (essentially “germ-killers”) are effective and safe. Although the number of vaccinated people continues to rise in the U.S. and globally, as of this writing, COVID-19 has killed close to 590,000 Americans and more than 3 million people worldwide and infected 32-plus million in the U.S. alone. The community effort—of doctors and medical personnel, first-responders, epidemiologists, public-health policymakers, safety and risk-assessment experts, architects, and of entrepreneurs and everyday people—has turned and evolved as the peaks of this crisis have razored across the population.

During the zeitgeist of the early 2020s, it is therefore understandable that laypeople and experts both would focus on how to contain pathogens or microbes. Into this charged discussion, we believe the idea of antimicrobials (that is, killers or inhibitors of microbes) has foist itself.

Within architecture and design specifically, the larger question remains, however: Are antimicrobials effective and safe in building materials, additives, or surfaces in the home? We explore some of the buzz around antimicrobial use herein and weigh it on its merits.  

As the Healthy Building Network (HBN) and global architecture and design firm Perkins and Will put it in their updated 2020 white paper: “[Even in the era of COVID-19] No evidence yet exists to demonstrate that products intended for use in interior spaces that incorporate antimicrobial additives actually result in healthier populations. Further, antimicrobials may have negative impacts [such as antimicrobial resistance, or AMR] on both people and the environment.”  

Let’s step into that “yet” and engage our skepticism muscles. But first, some information on what exactly microbes are and do, plus a little about the methods to control or mitigate them.  

Microbes Are All Around Us—and They Are Us 

Don’t be alarmed, but you are approximately at least half microbe. Or, as a December 2020 article by David Pride, an infectious disease specialist, puts it: 

Scientists’ rapidly expanding knowledge makes it clear that we are not made up primarily of “human” cells that are occasionally invaded by microbes; our body is really a superorganism of cohabitating cells, bacteria, fungi, and most numerous of all: viruses. The latest counts indicate that as much as half of all the biological matter in your body is not human (https://www.scientificamerican.com/article/viruses-can-help-us-as-well-as-harm-us/).

Like the other microbes (or microscopic life) that live in and on humans in our so-called microbiome, many viruses do not target our cells. Instead, they are there to parasitize bacteria (a.k.a. bacteriophages). The aforementioned Scientific American article compares the human body to a hunting ground. 

What does the existence of the microbiome and its microbes on, in, and outside of our bodies mean for the air we breathe, the surfaces we touch, or the objects we use? Controlling harmful microbes, via a product or process often deemed antimicrobial, obviously is critical for medical devices, air-exchange/ventilation systems, bathrooms, or food-preparation surfaces, especially in congregate settings.

A person sprays disinfectant in the desperate hope of mitigating COVID-19; such mists have been dubbed ineffective safety theater by infectious-disease experts. Photo by Dimitris Vetsikas on Pixabay.

Buildings such as hospitals, nursing homes, schools, and even some office buildings have employed various antimicrobial measures, such as UV light and/or the spraying of supposed disinfectants, to control potentially devastating infection. 

As far as the current battle against COVID-19, STAT News reported the following on White House misting in December 2020: “The World Health Organization specifically recommends against misting as a way to combat Covid-19 in both health care or non-health care settings, saying it is not only unhelpful, but can harm people in the space. So does the American Industrial Hygiene Association, which represents workplace safety and cleanliness experts. And according to the EPA, just three disinfectants—all based on hydrogen peroxide—are even effective against SARS-CoV-2 when used as a mist.”

And so, like many, you’ve probably wondered about the safety profile and efficacy of different antimicrobials in your own home. We’ll get to that important issue of “are antimicrobials effective” shortly. But first, how is antimicrobial defined? 

 FIFRA Governs Antimicrobial Use

Antimicrobial agents are “considered pesticides and are regulated differently depending on whether they are added to control disease-causing germs or used to preserve the product against decay.” 

Suzanne Drake and Melissa Coffin, of Perkins and Will and the HBN respectively, elaborate: “In the United States, the Environmental Protection Agency (EPA) regulates antimicrobial agents used in building products under the FIFRA (the Federal Insecticide, Fungicide, and Rodenticide Act). FIFRA defines a pesticide based on the function the substance provides to a product.” 

In addition, the EPA offers in-depth guidance on what exactly an antimicrobial pesticide is:   

“Antimicrobial pesticide” is defined in section 2(mm) of FIFRA as a pesticide that is intended to disinfect, sanitize, reduce, or mitigate growth or development of microbiological organisms; or protect inanimate objects, industrial processes or systems, surfaces, water, or other chemical substances from contamination, fouling, or deterioration caused by bacteria, viruses, fungi, protozoa, algae, or slime; and is exempt from or not subject to a tolerance . . . or a food additive regulation. 

Clear as mud, right? 

This explanation applies most to a discussion of antimicrobials in the kitchen: “In general, antimicrobial substances used on inanimate surfaces are subject to FIFRA, whereas antimicrobial substances used in or on living animals or humans are subject to the Federal Food, Drug, and Cosmetic Act (e.g., human or animal drugs, antiseptics, liquid chemical sterilant used on medical devices, etc.). Some antimicrobial products are subject to both FIFRA and FFDCA (i.e., dual jurisdiction products) because they involve direct or indirect food uses, or use on food contact surfaces. . . .” 

Food-handling and storage facilities (including the premises themselves and the equipment) such as restaurants and cafeterias, food storage or distribution facilities, and food or feed stores and markets are covered under these use patterns. 

Metals and other biocides

Now, back to the antimicrobial additives themselves, because these are probably most pertinent to normal residential (non-congregate) use patterns.

We happen to agree with the premise of this Contract Design article, which talks about the increased use of these antimicrobial additives, absent strong efficacy data, to “exploit a complex regulatory system, resulting in biocides that are incorporated into products solely to play on the mistaken belief that antimicrobial products are superior to standard ones.” 

In fact, public health and epidemiology experts agree about the overuse of antimicrobials because of the continuing—and worseningemergence of antimicrobial resistance seen in healthcare settings. 

Sara Balderi, principal designer at Designtex, a manufacturer of textiles and other applied materials, notes, “We share our experience and knowledge and are able to arrive at a solution that almost always does not include the use of antimicrobial additives” [emphasis ours]. 

Some people—especially those in the commercial interiors industry—have a lot to gain financially from antimicrobials, according to the previously cited Metropolis magazine piece, “Are Antimicrobial Materials and Surfaces Really What We Think?” Some entrepreneurial-minded folks are embracing metals such as silver (ions or as nanoparticle treatments) or copper, plus actual chemical agents such as “benzo- and methylisothiazolinone . . . as coatings, finishes, and treatments to fight the spread of bacteria, fungi, and viruses.” 

We, as many in the medical and architectural fields, do not believe these impregnated or treated antimicrobial wunderkinds are anything more than buzzwords built on a mountain of marketing hype and few stringent efficacy data. And then there is the very significant issue of antimicrobial resistance. 

Antimicrobial resistance (AMR) and antibiotic resistance

Remember the old adage that “what doesn’t kill me makes me stronger?” Microbiologically, there is some merit to that idea. Observe, for example, this letter to Science magazine (29 January 2021), “Disinfection spreads antimicrobial resistance.” It references the effects of overly robust disinfection of surfaces and skin, as well as chlorination, in the context of the novel coronavirus. These researchers write, “During the COVID-19 pandemic, the use of disinfectants, alcohol-based hand sanitizers, and antiseptic hand wash has surged. As a precaution, many authorities have also increased chlorine dosage in wastewater disinfection to achieve a free chlorine residual concentration greater than 6.5 mg/L, despite evidence that a free chlorine residual of just above 0.5 mg/L can completely inactivate coronavirus.” 

They emphasize that across-the-board disinfection protocols for COVID-19 specifically “should be limited to the minimum required to kill severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and weighed against their potential to increase antimicrobial resistance.” 

The term AMR is used interchangeably in some of the medical advisories (including the CDC’s) with antibiotic resistance, or AR. Regarding AR, the CDC’s latest guidance explains: 

Antibiotic resistance happens when germs like bacteria and fungi develop the ability to defeat the drugs designed to kill them. . . . Infections caused by antibiotic-resistant germs are difficult, and sometimes impossible, to treat. In most cases, antibiotic-resistant infections require extended hospital stays, additional follow-up doctor visits, and costly and toxic alternatives.  

Antibiotic resistance does not mean the body is becoming resistant to antibiotics; it is that bacteria have become resistant to the antibiotics designed to kill them (per the CDC).

It is because of the looming presence of these AR- or AMR-linked pathogens that the CDC and other worldwide health authorities have amassed reams of data supporting the so-called One Health approach. This initiative relates to healthcare and goes beyond it to touch on community settings or issues such as food production, schools, protecting ecosystems, and so forth. 

The CDC writes, “Antibiotic resistance has the potential to affect people at any stage of life, as well as the healthcare, veterinary, and agriculture industries, making it one of the world’s most urgent public health problems.” 

Human and animal health and environments are inextricably connected to one another. So, a synergistic, or synthesizing, approach also behooves us here in the architecture and design fields. 

We, therefore, believe that there are three best-practice approaches, detailed in the next section, shown to be most efficacious and safe with regard to building practices. They are backed up by many in the architectural field, such as Perkins and Will and the Healthy Building Network, which revisited the findings of their March 2017 white paper, “Healthy Environments: Understanding Antimicrobial Ingredients in Building Materials,” in late 2020 owing to the continuing coronavirus pandemic.  

Their 2020 reiteration affirmed again that: 

“Paints, and other touchable surfaces such as countertops, and virtually any product considered as an interior finish may contain one or a combination of antimicrobials. These agents are considered pesticides, but their identity—and related hazards—can be difficult for the average person to discover. This lack of transparency creates a hurdle for the informed selection of products with reduced negative impacts. No evidence yet exists to demonstrate that products intended for use in interior spaces that incorporate antimicrobial additives actually result in healthier populations. Further, antimicrobials may have negative impacts on both people and the environment” [emphasis ours].


Best Practices with Respect to Antimicrobials 

Advanced air filtration is one of the best practices currently available—not ultraviolet lamps/bulbs, antimicrobial countertops, door guards, or paints/fabrics with antimicrobial additives—in the commercial or residential setting, although it can be expensive. 

In short, where antimicrobials are not effective, ventilation powers through for the figurative win in infection control.

Commercially used so-called germicidal lamps, which use UVC light, provide more efficacy than simple home models you might buy online. Even UVC, however, has drawbacks, including dose-dependent harmfulness to human health, per the FDA, which says, “… currently there is limited published data about the wavelength, dose, and duration of UVC radiation required to inactivate the SARS-CoV-2 virus.”

Harvard’s Healthy Buildings program leader Joe Allen says: “I think we’ll soon be in a place where ‘acceptable’ [ventilation] is no longer acceptable.” Allen is also an assistant professor of exposure assessment science, in addition to leading the Healthy Buildings program at Harvard’s T.H. Chan School of Public Health. “The goal will be optimal. The goal will be healthy indoor air quality.”   

As such, from all the research we have done and in communication with our architectural peers, we believe the three following approaches are the most cost-effective and efficacious when infection control is critical to a built environment: 

  1. Build robust ventilation systems.
  2. (related to 1) Incorporate outdoor air-exchange whenever possible for single-family residential, commercial, or multifamily settings.
  3. Use touchless surfaces, automation, or workarounds for high-use areas such as door handles and light switches, especially for any type of public congregate settings, in healthcare, schools, offices, and the like.

Further, we recommend that you take healthcare experts’ advice regarding AMR and AR very seriously under consideration and decide if you want to be involved with potentially negative or at least unproven antimicrobial additives, finishes, or materials (e.g., benzo- and methylisothiazolinone, copper, brass) until research establishes more solid efficacies of their use in your particular building situation (single-family versus multi-family).

Will Coronavirus Changes be Akin to the ADA? 

Many speculate that the ongoing coronavirus pandemic will create as much of a sea change in architecture and design going forward as the passing of the Americans with Disabilities Act did. Debates swirl and sometimes rage around new and existing air-handling for buildings, according to architect Brad Simmons, managing partner at KAI Enterprises, who referenced a Leo Daly study on pandemic-era spaces. 

The same Construction Dive piece says the Daly research indicates that “several types of air containment and sanitization systems used in hospitals will become more mainstream in sectors such as hospitality,” including: 

  • Negative-pressure air handlers.  
  • High-performance ventilation.  
  • Antimicrobial, antibacterial and/or UV light. 
  • Outdoor air exchangers.

So, Are Antimicrobials Effective in the Home?

In a nutshell, you will want to look to tools other than unproven antimicrobial substances on inanimate surfaces or materials with antimicrobials. We recommend you use the three best-practice approaches highlighted above to maximize your budget while addressing the issue of healthy buildings, including single-family residences.

And, should you require additional expertise in renovating or creating a wholly new home or other living space, you know where to find us! Thanks, as always, for reading and we look forward to taking your project from dream stage to stunning reality.


 Additional Reading: 



“Effects of space sizes on the dispersion of cough-generated droplets from a walking person,” from Physics of Fluids, https://aip.scitation.org/doi/10.1063/5.0034874