How Bad Is It Really to Use Disinfectant All the Time?

The coronavirus pandemic seems to have spawned a culture of germophobes, with Americans zealously squirting on sanitizer and disinfecting their homes. According to the market research firm Research and Markets, sales of household cleaning products have skyrocketed 195 percent due to COVID concerns.

Public areas are also hubs of hypervigilant hygiene. In office buildings, schools, gyms, movie theaters and restaurants, foggers mist cleaning agents over desks, chairs, countertops and tables.

But what kind of a toll is excessive sanitation taking on our health? And for that matter, how much is it actually doing to protect us from infection anyway? Put down that bottle of Lysol and read on.

In short: not very.

"Our understanding about how SARS-CoV-2 is spread has changed over time," says Joseph Allen, director of the Healthy Buildings Program at Harvard University, associate professor of Exposure Assessment Science at the T.H. Chan School of Public Health and chair of the Lancet COVID-19 Commission Task Force on Workplace, School and Travel Safety. "Early on, the CDC, World Health Organization and others were highlighting close contact transmission, with some transmission through contaminated surfaces, or what we call fomites — so it was reasonable that people were disinfecting surfaces frequently and routinely."

"We had limited information at the start of the pandemic, and so a narrative took hold," says MarkAlain Déry, DO, MPH, medical director of infectious disease for Access Health Louisiana. "The narrative was that everything had to be washed down."

But now it's clear that airborne transmission is driving the pandemic. A September 2020 review in the ‌Annals of Internal Medicine‌ found that fomite transmission is rare — and that even in the few presumed cases, respiratory transmission couldn't be entirely ruled out.

"At this point, we know that while fomite transmission ‌can‌ happen, it is not the dominant mode," Allen says. "You will not have a superspreader event through fomites, whereas with airborne transmission we have seen outbreaks where 90 percent of people in the space are contaminated by one person."

Dr. Déry explains that the quantity of viral particles is more pronounced when it travels through the air. If an unmasked person with COVID coughs on a table and you then smear your hand on it and stick your finger in your nose, you will not get as much of the virus in your system as you would if the person coughed in your face.

"Your hands are poor transmitters of the virus," Dr. Déry says. "Moving the pathogens from a fomite to a portal entry — like your eyes, mouth or nose — is not an effective way to spread the infection."

Furthermore, if you do touch a contaminated surface, simply washing your hands will prevent the virus from spreading.

"The reality is that shared air is the problem, not shared surfaces," Allen says. "And the effective method to kill the virus in the air is to dilute or filter out respiratory particles through ventilation."

But the question remains: Is overzealous sanitation actually doing us any harm? Potentially.

"Not only are far too many organizations spending valuable time and resources focusing on surfaces rather than airborne transmission," Allen says, "but the cleaning chemicals used are often respiratory hazards."

Most disinfectant sprays include volatile organic compounds, or VOCs.

"VOCs are designed to evaporate quickly," Allen says. "They volatize, which means the chemicals start in a liquid solution but then enter the gas phase where they can be inhaled through the air."

According to the Environmental Protection Agency (EPA), exposure to certain VOCs may result in eye, nose and throat irritation; headaches; loss of coordination; nausea; damage to the liver, kidneys and central nervous system; and cancer.

"You are using these chemicals on surfaces to disrupt the biology of a virus or bacteria," Allen says, "So it would make sense that they are not going to be benign on your own cells if inhaled."

How much of an affect these toxins have on your health depends on the concentration you are exposed to, which is determined by A) the quantity of disinfectant used and B) how quickly it is diluted through ventilation.

"Often, organizations are cleaning so frequently that the levels of the VOCs build up in the air, creating a potential respiratory hazard for people in that space," Allen says.

To put this into perspective, imagine someone smoking a cigarette indoors.

"If you have really good ventilation, you would be able to smell the smoke, but it may not be overwhelming or all that visible," Allen says. "Compare that to a room with very low ventilation, where you can see and smell the smoke — it would be overwhelming."

Scientists measure ventilation rate via "air changes per hour," or ACPH, which refers to the number of times air exits and enters a room every hour. According to Allen, a typical home gets half an ACPH, so it can take several hours to remove 95 percent of what's in the air.

Allen's team recommends schools get 6 ACPH. "At that rate, you can remove the majority of anything in the air within 30 minutes," he says. (That said, the average school clocks in at 1.5 ACPH.)

Ventilation rates are also variable by season — for example, if the windows are open when the weather is nice.

"We recommend 4 to 6 ACPH for COVID protection, but even buildings with low ventilation rates can be leaky to some extent, so air exchange and dilution is still happening," Allen says.

In other words, if your workplace or your kids' school mists down surfaces at the end of the day, the VOCs will be diluted enough by the following morning that they won't pose a peril to your health — even if the room is poorly ventilated.

But it's a different story if you're the one constantly spritzing on disinfectant.

"It is acute exposure we are worried about," Allen says. "And for workers like janitorial staff who have to apply these chemicals all day at work, it is a particular concern."

Mahboobeh Mahdavinia, MD, PhD, associate professor of allergy and immunology at Rush University, reports that the number of patients she has seen with rashes on their hands has doubled since the pandemic began.

"Contact dermatitis manifests in redness and inflammation, while eczema causes dry, scaly, itchy skin," Dr. Mahdavinia says. "They can both be allergic reactions to frequent disinfectant and hand sanitizer use."

It sounds contradictory, but an overly clean environment can make it harder for your body to fight off infection.

One theory, dubbed the hygiene hypothesis, suggests that children need exposure to germs in order to "educate" their immune systems so they can learn how to defend against infection. A landmark study in the August 2016 issue of ‌The New England Journal of Medicine‌ discovered that children with greater microbial exposure had more robust immunity than those raised in more sanitary households.

"This is particularly important in the first few years of life, when the immune system is developing," Dr. Mahdavinia says. "Research has found that kids who grow up in an overly sterile home are more prone to allergic diseases, such as eczema, asthma, food allergies and allergic rhinitis."

What's more, because "good" bacteria plays a crucial role in fending off infection and keeping people of all ages healthy, even adults' immune function can be affected by excessive hygiene.

"Over-cleaning will destroy the good bacteria as well as the bad," Dr. Mahdavinia says.

When you grab a disinfectant wipe with your bare hands, you'll obliterate the microbiome of helpful bacteria on your skin — which in turn can harm your gut microbiome. For adults, the effects are fleeting, and the good bacteria will begin to grow back within hours of touching disinfectant.

But for small children, the effect can be long-lasting.

"It is hard to redevelop a thriving microbiome after the first three years of life," Dr. Mahdavinia says. "If you have lost some of the good bacteria, it is challenging to reintroduce it into the body."

Young children frequently put their hands and other objects in their mouths. Dogs and cats have a tendency to lick surfaces.

"If some of the toxic chemicals used in disinfectant products are accidentally ingested, it might create GI distress like nausea, diarrhea and vomiting," Dr. Mahdavinia says.

Just imagine your fur baby gnawing on a coaster that has been recently wiped down or your toddler rubbing her hands on a Lysol-coated tabletop and then sucking her thumb.

Certain health issues can make your respiratory system extra sensitive to the toxic irritants in disinfectant sprays.

"It can cause wheezing in people with asthma, vocal-chord dysfunction or hyperosmia, a heightened sense of smell," Dr. Mahdavinia says.

Dr. Déry says other people at heightened risk include those with pulmonary or respiratory disease, such as lung cancer or cryptogenic organizing pneumonia.

In that case, the benefits of disinfecting outweigh the downsides. Frequently wipe down high-touch surfaces, like doorknobs, handles, light switches, countertops, toilets, faucets and sinks using an EPA-approved COVID-fighting disinfectant.

"The person with COVID should isolate as much as possible from the rest of the household," Dr. Déry says. "Everyone should be masked and washing their hands often."

Unless you have an underlying respiratory disease, you're the parent of a small child or you have to perform extensive spraying as part of your job, it's not something you need to worry about.

"We are exposed to these types of chemicals all the time," Dr. Déry says, adding that the greatest risk may well be that this "hygiene theater" creates a false sense of security against COVID.

Mainly, the experts agree that it's simply unnecessary: a waste of time, energy and money that would be better put toward enhanced ventilation and air filtration.

"If this strategy of disinfecting surfaces significantly reduced the risk for COVID transmission, I would be all for it," Allen says. "But we know that is not the case, so why are we focusing so much of our attention on shared surfaces over shared air?"

That said, many other pathogens ‌are‌ spread through fomites (bacteria are a biggie), so it's not a bad idea to disinfect surfaces.

"Just be selective in how you do it," Allen says. "You don't need to deep clean every day in your home, and if cleaning is being used as a rationale for keeping kids out of school, that is not an effective risk-reduction strategy."

According to Dr. Mahdavinia, taking extra cleaning precautions during the pandemic is OK. "But in normal times, these disinfectants should not be used on a regular basis at your home aside from in the bathroom," she says.