The science of sanitizing your home’s air

Germs are everywhere: on you, your dog, in your yogurt. Many of these microorganisms are harmless, but there are some to watch out for — i.e. pathogens, microorganisms that can cause disease. During the pandemic, many of us became hyper aware of infectious diseases that can be transmitted through the air we breathe, especially as we learned that Covid-19 rapidly spreads via airborne particles and droplets.

The good news? “Since illness-causing pathogens are the minority of [most] bacteria and viruses, that means they are also the minority of those you’ll find in your homes,” said Andrea Love, a biomedical scientist with a PhD in Microbiology and Immunology.

Nevertheless, the average person spends 90 percent of their time indoors. Coughing, laughing, sneezing, talking, and even flushing — all of these common household activities can lead to viruses and bacteria becoming airborne in our homes, and contribute to the spread of pathogens. For this reason, maintaining more sanitary air is a practice we can all begin incorporating at home. “Good hygiene practices include good air hygiene,” said Love.

Luckily, just as there are ways to sanitize your bathroom sink and kitchen countertops, there are effective, easy ways to maintain more sanitary air in your home.

Before we get into the science behind sanitizing, it’s helpful to know which germs might be floating around in your air. If you’re worried about infectious diseases, the main ones that might show up fall into two camps: respiratory and gastrointestinal illnesses. You’re most likely to find germs that cause these illnesses in the air because that’s the way they spread.

When someone’s infected with an illness, they can bring those germs into your home. People spread pathogens responsible for respiratory illnesses through tiny droplets of saliva when they sneeze, cough, talk, laugh, sing, and even breathe. Someone infected with a gastrointestinal disease can spread germs into the air if they vomit or flush the toilet.

Common airborne respiratory pathogens include influenza viruses, common cold viruses like rhinoviruses, respiratory syncytial viruses (RSVs), human coronaviruses and enteroviruses.

Airborne bacterial pathogens include Streptococcus pneumoniae, a bacteria behind some forms of pneumonia, ear infections, sinusitis, and bacterial meningitis; Bordetella pertussis, the bacteria behind whooping cough; and Streptococcus pyogene, which causes strep throat. Common gastrointestinal pathogens that can be spread through the air include noroviruses, rotaviruses, and adenoviruses, and the bacteria E. coli.

Airborne transmission is a complex process. Any time you force air out of your nose or mouth, you unknowingly disperse small particles of fluids that can hold microorganisms. Transmission of infectious diseases involves airborne droplets and aerosol particles. A person infected with the flu might sneeze and spew droplets from their mouth, while also releasing smaller aerosol particles into the air. The difference is mainly in the size.

“Droplets typically spread short-range and land in the mouths or noses of people in the immediate vicinity,” said Love. “These aerosolized particles can remain suspended in the air for hours, travel further, and recirculate longer, particularly in poorly ventilated areas because gravity doesn’t pull them to the ground as quickly due to their small size.”

Your environment can also impact how long droplets and aerosolized particles stick around. In general, having a large number of people talking in your space will increase the number of microorganisms floating around.

“High humidity levels can also lead to droplets becoming larger by aggregating with water in the air, and low humidity can cause droplets to fall out of the air as a result of evaporation,” Love said. “Poor ventilation in a room can cause stale air to remain in the room, whereas opening a window or having an air purifier in place can cause the exchange with clean air.”

While ventilation, air circulation, and air filtration can all help get rid of any aerosolized pathogens in your home, there’s another method that should be on your radar: air sanitation. “Sanitizing the air is a tool that is routinely used in healthcare and laboratory settings, for the exact same reason you disinfect surfaces: to remove potentially harmful microorganisms,” said Love.

Lysol Air Sanitizer in particular is the first product approved by the Environmental Protection Agency to kill 99.9 percent of both viruses and bacteria in the air when used as directed.

The key is the product’s active ingredient: dipropylene glycol. This ingredient is hygroscopic, meaning it has the ability to absorb moisture from the surrounding environment. So, when the dipropylene glycol in Lysol Air Sanitizer comes into contact with, say, an airborne bacterium, it increases the osmotic pressure outside the bacteria member. This external increase in osmotic pressure causes water to leave the bacteria member, which becomes dehydrated. The bacterial cell cannot adapt to this stress, and its cell mechanisms cease functionality.

“This leads to cell death of bacteria,” Love said. “Instead of exchanging stale or contaminated air with fresh air, this process uses chemicals to physically inactivate microorganisms that may cause an illness, just like you would do when cleaning a surface with a disinfectant,” Love said.

Ultimately, Love said, using an air sanitizer, alongside ventilation, surface sanitation and other cleaning techniques, can be a part of a “multi-pronged approach” to help remove potentially illness-causing pathogens from your home. “Nothing is perfect,” Love said, “but the reality is, you can decrease your risk with a few proactive measures and reduce the likelihood of getting sick.”