Brass “touchless” door opening hooks (or keys) are showing up all over the internet with a simple pitch: use them instead of your fingers to open doors and punch keys to protect yourself from germs. Brass is an alloy of copper and usually zinc, and copper does have antimicrobial properties. So, will it protect you from germs and more importantly, COVID-19? Probably not, and here’s why.
Copper Does Have Microbial Properties
The first thing to know is that copper really does have antimicrobial properties. That’s why you’ll find brass used on frequent contact items like doorknobs and push plates. But it’s not instant germ death; it can take as long as two hours for copper to kill a wide range of harmful microbes.
We’ve known about copper’s antimicrobial properties for centuries, and the EPA has thoroughly tested it against several viruses and bacteria types, including E. coli, Staphylococcus aureus (MRSA), Influenza A virus, and even fungi. Depending on the purity of the copper, the results were pretty outstanding, with a kill ratio of 99.99% within 2 hours.
We Haven’t Tested It Against SARS-CoV-2
However, it doesn’t mean copper kills every type of bacteria and virus. The number of germs we have tested is far less than the strains of viruses, bacteria, and fungi that exist in the real world.
We haven’t thoroughly tested it against SARS-CoV-2, the virus that causes COVID-19. Without that testing, we can’t be sure it works at all against SARS-CoV-2, and it might not. Even the Copper Development Association, a nonprofit tasked with ensuring the proper public claims of copper, says as much in an official statement on its site. Officially, the EPA only allows claims against six types of bacteria (not viruses).
In early testing, some studies have shown that copper may be effective against SARS-CoV-2 in 4 hours, which is double the time of other bacteria and viruses we’ve tested. But we’ll still need more testing to know for sure.
Copper Doesn’t Prevent Cross-Contamination and Requires Cleaning
In every statement about copper’s antimicrobial properties, you’ll find two included details that matter a great deal to brass hooks. Dirty copper doesn’t kill microorganisms as effectively, and copper won’t prevent cross-contamination. Here’s the Copper Development Association’s version of that:
Laboratory testing shows that, when cleaned regularly, uncoated copper alloy surfaces kill >99.9% of the following bacteria within 2 hours of exposure: MRSA, VRE, Staphylococcus aureus, Enterobacter aerogenes, Pseudomonas aeruginosa, and E. coli O157:H7. Copper surfaces are a supplement to and not a substitute for standard infection control practices and have been shown to reduce microbial contamination, but do not necessarily prevent cross contamination or infections; users must continue to follow all current infection control practices.
Note the “regular cleaning” and “do not necessarily prevent cross-contamination” portions of the statement.
You’ll see that hinted at in nearly every brass key’s marketing if you look closely. Usually, the terminology is something to the tune of “with regular cleaning and proper handling.” Without cleaning, copper becomes less effective at killing microbes. Or rather, a barrier of dirt and grime builds up that prevents the copper from killing bacteria.
So, the more you handle your brass or copper key without cleaning it, the worse it gets at the one you thing you want it for—killing germs. And given that it can take hours for copper to do its job, if you use a hook to open a door, shove it in your pocket, then shove your hand in your pocket to get it back out—you probably defeated the point entirely. Copper can deposit germs before it kills them.
That’s why most brass hooks manufacturers depict the devices hanging from a belt loop or key chain. But even that’s not a perfect solution; you’ll have to be diligent not to touch the part of the hook that touched a door or PIN pad, or not to brush your hand against the part of your pants that makes contact with your brass hook.
How do you clean copper? Well, that depends on what made it dirty, and how sanitary you want to make the hook. But according to the Copper Alloy Stewardship, “standard hospital cleaners are compatible with antimicrobial copper materials…” but you need to be careful to use something that won’t leave the surface “waxed, painted, lacquered, varnished, or otherwise coated.” That goes back to interfering with the interaction between copper and germs.
And, of course, if the brass hook you buy turns out to be brass plated, then you run the risk of damaging the brass while cleaning it, thus destroying any chance of killing germs.
So, What Should You Do?
You may be wondering if brass hooks aren’t the magic bullet to protect yourself from germs, what can you do? Well, there isn’t a singular magic bullet, unfortunately. The EPA does have a list of disinfectants that are effective against SARS-CoV-2, but you’ll likely find them in short supply.
As the CDC suggests, the best thing you can do is wash your hands thoroughly, and avoid touching your face and nose when you’re out in public. Wearing a mask can not only help protect you from infection, but it may also help with the goal of not touching your face. It’s a physical barrier, after all.
Even if you do use a tool like a brass hook, you’ll still need to wash your hands early and often. Did you handle the brass hook to open a door? Wash your hands anyway. And specifically, you’ll need to do so for at least 20 seconds with hot water and soap.
If you want the perfect version of washing your hands, you can go beyond singing happy birthday twice and follow the World Health Organization (WHO) protocol. Google will help you with that if you ask.
And naturally, in addition to good hygiene, self-isolation is a good defense against infection. The more people you encounter, the higher your risk of exposure. Conversely, avoiding people also avoids the risk of exposure. And if you still aren’t sure, check reputable sites like the CDC and NIH for more information.
But ultimately, $20 spent on soap and hot water is a safer bet to protect you from infection than a brass hook filled with vague but just inside the bounds of legal promises.