Everyone’s favorite frustrating, hard-to-clean, potentially dangerous household device

It’s winter, which means it’s humidifier season. If you struggle with dry skin, allergies, or you’re currently dealing with a cold, you might be leaving yours on all the time — or you’re scrolling through yet another humidifier review roundup to choose a model to purchase. Should you buy an ultrasonic or evaporative? Warm mist or cool? Should it be a top-fill design? Are all the parts dishwasher safe? How big of a tank should you look for?

In a marketplace full of new-fangled, hyperspecific home gadgets, the humidifier is a classic appliance with modern(ish) incarnations available since the 1960s. Over 20 million were sold in the US in 2019, according to Statista, but they’ve only grown more popular and sleeker in the last few years, as people have become more concerned with the quality of the air in their homes. According to Amazon, over 100,000 units of this popular humidifier were purchased in the past month.

But while most of the sleek gizmos we love to buy during Black Friday sales exist to, in theory, optimize our lives, the humidifier adds a bunch of hassle — taking care of it becomes another irritating chore in the never-ending wrangling of your household, requiring a thorough scouring every few days to ensure no mold or bacteria is growing. There’s no shortage of humidifier models on the market, but you might be hard-pressed to find one you genuinely love rather than merely tolerate. Those looking for buying advice online often qualify their query: How do I not only wade through the options to find a humidifier that works well for my space, but also one that isn’t a complete pain to clean?

The short answer is that there isn’t a magical way to avoid humidifier maintenance. A humidifier is supposed to be full of liquid, and where there’s moisture, mold and bacteria will grow.

What’s more, there are real dangers to misusing a humidifier. More research is needed on the long-term health impacts of using them, which is a little disturbing considering how commonplace it is as a household object. The worst mishap that might occur with a robot vacuum is that it runs over an unpleasant surprise your dog left on the floor. With humidifiers, you could be breathing in particulate matter that causes more serious health issues than the device purports to solve. Yet for how risky and frustrating they are, consumers remain obsessed with looking for, testing out, and debating what the least worst humidifiers on the market. 

Why we love to hate humidifiers

The humidifier, in its basic form, is extremely simple — you can increase humidity simply by setting out a bowl of water near a radiator. (Whether this will make a meaningful difference is another matter.) Dry air can worsen any congestion you’re dealing with, sap moisture from your skin, exacerbate your asthma, and even hurt your house plants. Humidity falls in the winter because the colder the air, the less water vapor it can hold. But it’s not just the frigid conditions outside that contribute to unbearably dry air in the winter. “It’s the heat that you’re using in your domicile that ends up often reducing the humidity,” says Allen St. John, senior tech editor at Consumer Reports, noting that he sometimes turns down the heat to bump up the humidity rather than using a separate machine to do so. (If you don’t control your own heat, this may not be an option.)

Older humidifiers often looked like terrifying contraptions and were used mostly in hospital settings to help people with respiratory conditions. In the latter half of the 20th century, they started being advertised as consumer-grade products to use at home. Today there are three types available: the ultrasonic, which uses vibrations to turn water into mist; evaporative, which uses a fan to help evaporate water into the air; and the warm mist humidifier, which boils water to produce steam. 

“Most of the stuff that’s on the market tends to be ultrasonic at this point,” St. John says. They’re generally easier to use, and typically quieter.

But all kinds of humidifiers come with trade-offs. Ultrasonics appear to emit a lot more particulate matter than evaporatives do (more on that later); evaporatives can not only be louder, but might also require you to buy and replace a filter or wick. With warm mist models, you run the risk of scalding yourself (or a pet or child in the house) if you knock over the humidifier. None are particularly easy to maintain: The Environmental Protection Agency advises cleaning a humidifier every three days, which requires taking it apart and getting into every little crevice to remove grime, and emptying the tank daily to reduce the growth of microorganisms.

“You don’t want to leave a humidifier around that’s just kind of wet,” St. John says. The area around the machine should be wiped down if there’s moisture around it. It’s also important, though, to be careful about what cleaning agents you use and how well you rinse the humidifier before turning it on again — you don’t want to inhale any harmful chemicals. In South Korea, humidifier disinfectants that were widely available until 2011 have been linked to the deaths of over 1,800 people.

Given how frustrating they can be to own, people often have impassioned opinions on humidifiers, according to Thom Dunn, who writes Wirecutter’s humidifier guide. “It’s a perennial thing — I’m always hearing reader feedback about it,” he tells Vox. 

A few years ago, there was a considerable amount of reader complaints and discourse around the fact that Wirecutter had named the Honeywell HCM-350 humidifier, currently $67.99 on Amazon at time of publication, their top pick for several years. The humidifier guide is “easily one of the most volatile reader comment sections,” Dunn says. The team eventually removed the HCM-350 from their recommendations. The top pick now is the $109.99 Levoit LV600S. Unsurprisingly, several recent comments disagree with the choice. One of the latest comment reads: “I think it’s crazy the Honeywell HCM 350 is no longer the top pick.” (McSweeney’s even lampooned how even the most recommended humidifier will inevitably disappoint.)

This constant debate about the least-annoying humidifier may also be fueled by the fact that it’s a product some replace every few years. Many models are relatively inexpensive, and “it’s easy to get to the point of, ‘I didn’t really clean it, now this thing looks like a science experiment,’” St. John says.

In the “introvert economy,” humidifiers are becoming more popular (and slightly less ugly)

There’s another obvious reason humidifiers cause so much consumer disdain: Many of them are big, clunky, and frankly, ugly. The good news is that the age of marginally more attractive design may be upon us. We’ve already seen the premiumization of kitchen gadgets, from toaster ovens to espresso machines, and a few years back, window air conditioners started getting the minimalist edit too. Now, more brands are giving the humidifier the millennial-sleek update thanks to a broader “air care” wellness trend — which includes not just humidifiers, but candles, diffusers, air purifiers — that’s turning anything that treats your indoor air into a premium product that should also blend into your home decor.

Some consumers are shelling out a lot of money for these prettier, more expensive models that can cost upward of $150 while not holding as much water or humidifying as well as experts’ recommended picks. “It does go along with a certain influencer wellness aesthetic,” Dunn says.

Consumers with discretionary income are investing more money into creature comforts for the home in general. “One of the things we’ve seen that sort of started with the pandemic — and that I don’t think has completely disappeared — is something we refer to as the introvert economy,” says Amy Eisinger, head of content at the wellness digital publication Well+Good. People are “investing in really making their space feel like a sanctuary.” Some are even installing infrared saunas in their homes, Eisinger notes. 

Even if you’re not quite bed rotting, chances are you’re spending more time at home these days than, say, a decade ago — and what we spend money on may be shifting alongside that fact. There’s a whole TikTok genre advertisements featuring a woman coming home from work and embarking on a convoluted ritual using niche smart home gadgets: She sanitizes her clothes with a UV light wand in the foyer, runs her earrings through a jewelry cleaner, washes vegetables for dinner with some kind of ultrasonic device, gives herself a foot bath while watching a show on her phone, and pours herself a glass of something stiff from a rotating decanter. Everything is clean and nothing hurts. Presumably, in such a world of ultra-modern optimization, your indoor air is always the perfect humidity, too.

The potential danger of humidifiers may not outweigh its benefits

The real issue with humidifiers isn’t just the annoyance of taking care of them, though, it’s that they can be a serious health hazard.

“What most people don’t know about ultrasonic humidifiers is that they will create a lot of small particulate matter,” says Jonathan Jarry, a science communicator at McGill University’s Office for Science and Society. They “aerosolize minerals that are present in the water,” which means the purity of the water you’re using in a humidifier can drastically impact your home’s air quality.

A few years ago, University of Alberta scientists published research showing that ultrasonic humidifiers using both filtered and unfiltered tap water released high concentrations of particulate matter seen “during extreme air pollution events in major metropolises.” A 2023 paper published in the journal Science of the Total Environment found that safe-to-drink tap water used in ultrasonic humidifiers could spew out dangerous levels of metals that are more harmful inhaled than when ingested, such as manganese. In short, using anything but distilled water in your humidifier means you could be inhaling a lot of stuff you probably don’t want in your lungs. (Evaporative humidifiers can also emit particulate matter, but to a lesser extent.)

The EPA recommends using only distilled water in humidifiers, but acquiring large enough quantities of it cheaply is easier said than done. To be clear, boiling water is not the same as distilling it, and bottled drinking water isn’t usually distilled either. Distillation requires boiling water “into a vapor and leaving behind any impurities, and then taking that vapor and recondensing it back into a liquid,” Jarry says.

How much distilled water you’ll need depends on how dry the air currently is and the size of the room you’re humidifying: A small space under 400 square feet might need a machine with a 1.5 gallon tank, according to CNET, while a bigger space over 1,000 square feet could require a 3-gallon one. Two five-gallon barrels of distilled water sell for $42.99 on Amazon at time of publication; a much cheaper option might be to buy a water distiller for your home, or signing up for a distilled water delivery service, but that still adds another step and expense to using your humidifier.

It’s unclear how much public awareness there is about the harm of particulates released by humidifiers. According to a recent Centers for Disease Control and Prevention report, many Americans have misperceptions about the purity of tap water. A third of respondents to a survey thought that tap water was sterile, and a quarter said they used it for humidifiers. (An unscientific Reddit poll on r/NewParents a few years ago shows the majority of 228 respondents saying they used tap water in humidifiers as well.)

The big question mark around the safety of these popular products adds yet another hurdle for consumers half-heartedly trawling the market for a humidifier that won’t make them miserable. The perfect all-in-one portable humidifier that distills water for you, cleans itself, and sings a lullaby for you at night does not yet exist. (The Dyson air purifier and humidifier combo does, but its regular price is $999.) If you’re not prepared for the commitment of bringing a humidifier into your home, the healthiest option — for both your lungs and your sanity — might just be to opt out.