Does a humidifier help dry eyes?

A humidifier can help when dry indoor air is part of why your eyes feel dry. Moister air slows evaporation from the tear film between blinks. The EPA recommends keeping indoor humidity between 30 and 50 percent, so measure the room with a hygrometer, run the humidifier until you’re in that range, and clean it as its maker directs.

Can low humidity cause dry eyes?

Low humidity makes it easier for eyes to feel dry. The tear film covering the eye has three layers: mucus against the surface, water in the middle and a thin oil layer on top. Between blinks, water evaporates from it. The drier the air, the faster that happens, so in a room at low humidity the film can thin out before the next blink restores it.

Low humidity isn’t the only reason eyes feel dry, and a humidifier won’t change the others, such as long screen sessions that cut down your blink rate. It deals with one part of the picture: the air.

Dry eyes humidity level: what to aim for

The U.S. Environmental Protection Agency’s guide to indoor air quality, “Care for Your Air,” says to keep indoor humidity between 30 and 50 percent. The EPA’s mold guidance gives the same 30 to 50 percent as the ideal and says to keep humidity below 60 percent if possible, because high humidity raises the chance of mold.

That gives you a target from both directions. Below 30 percent, the air is dry enough that you may feel it in your eyes, nose and skin. Above 50 percent, you start trading eye comfort for damp problems in the house. More moisture isn’t always better.

Measuring it with a hygrometer

The EPA suggests a moisture or humidity gauge, available at most hardware stores, to see where your home stands. These hygrometers are small and inexpensive. Put one in the room where you spend the most time, away from the humidifier’s mist, and check it at different times of day.

• Read it first thing in the morning, before the humidifier has run, to see your baseline.
• Read it again after the humidifier has been on for an hour or two.
• Check on a cold, windy day and on a mild one; outdoor weather changes indoor readings.
• If the reading climbs past 50 percent, turn the humidifier down or off for a while.

Does humidity make your eyes dry?

High humidity doesn’t dry the eyes; it slows evaporation. But very humid rooms bring their own problems for the house, and a humidifier pointed straight at your face can feel cold and damp rather than soothing. Set it a few feet away, with the mist directed into the room rather than at you.

Where a humidifier helps most

• The bedroom, where you spend hours with the door shut and furnace air building up.
• A home office, especially with a space heater in it.
• Any room where the hygrometer reads below 30 percent in winter.

Heated air is the usual culprit in winter; winter heating and dry eyes covers the furnace side, and dry eyes from a space heater covers portable heaters.

Keeping the humidifier clean

A humidifier holds standing water, so cleaning matters. Follow the manufacturer’s instructions for how often to empty, rinse and disinfect the tank, what kind of water to use, and when to replace any filter or wick. Don’t leave water sitting in the tank for days, and dry the parts before storing it at the end of the season.

Where eye drops fit alongside it

A humidifier changes the air; a lubricating drop works on the eye itself. Quell’s Uses section reads: For use as a protectant against further irritation or to relieve dryness of the eye. The directions are Apply 1 drop 3 times per day in each eye. Quell is designed to reinforce the tear film’s oil layer to help reduce moisture loss, which works alongside moister air rather than replacing it.

Keep the bottle out of the humidifier’s path, too. Damp air won’t matter to a closed bottle, but the tip should stay clean: Do not touch tip of bottle to any surface to avoid contamination. Store it in its range, Store between 15° to 30°C (59° to 86°F). The full label is on the Drug Facts page.

If the air isn’t the answer

If your eyes still feel dry with the room in the 30 to 50 percent range, the air probably isn’t the whole story. The label says when to stop and see a doctor: Stop use and ask a doctor if you feel eye pain or changes in your vision, if irritation or redness continues, or if the condition worsens or persists for 72 hours.