If you’re not careful, combating dry winter air could put a whole new problem on your plate this winter.

When temperatures drop and cold and flu season kicks in, many turn to humidifiers to soothe symptoms like sore throats, chapped lips and sinus dryness. Humidifiers also offer relief to those suffering from chronic conditions like asthma or COPD, making breathing easier and more comfortable.

But adding moisture to the air comes with a serious risk that could worsen the very symptoms you’re trying to alleviate.

Humidifier lung, also known as hypersensitivity pneumonitis (HP), is an inflammatory lung condition triggered by exposure to contaminated humidifiers.

Standing water in humidifiers can be a hotbed for microorganisms such as bacteria, fungi, and amoebae. When these particles are aerosolized, they can cause symptoms such as cough, shortness of breath, fever, chest tightness, fatigue, chills, and muscle aches.

Symptoms can be acute, developing within hours of exposure and lasting a few hours or days. However, chronic exposure can lead to symptoms that develop slowly and worsen over time.

Chronic symptoms can also include weight loss, bulging and/or discoloration of the fingertips and toes, a persistent dry cough, and worsening fatigue.

Over time, HP can cause lung scarring and hypertension.

Treatment begins with the immediate removal of the contaminated humidifier. In some cases, a course of oral steroids is administered.

Experts caution that even with medication, symptoms will continue if exposure continues — and chronic symptoms can persist and intensify even after exposure stops.

Acute HP typically clears within a few days; for cases with low-level, more long-term exposure, symptoms can persist for months.

But for those with chronic HP, symptoms rarely disappear but can be managed with medications.

Roughly 5% of people with acute HP develop chronic HP. 

The condition is diagnosed based on symptoms, personal history, oxygen levels, and assessment of exposure to allergens in living or working environments.

Additional analyses, such as chest x-rays, allergy blood tests, pulmonary function tests, and/or bronchoscopy, may be performed.

Experts maintain that cleanliness is critical to avoiding HP. Using distilled water rather than tap water when using an ultrasonic humidifier, cleaning humidifiers with vinegar or hydrogen peroxide every 3 days, allowing them to dry completely between uses, and regularly changing the filter are all important.

Manuals for individual humidifiers are typically available online and include specific instructions for care and cleaning.

However, it would seem no one is reading; according to Consumer Reports, 40% of people with humidifiers rarely or never clean them.

Alternative measures to combat dry air without a humidifier include visiting a steam room, staying hydrated, using saline-based nasal sprays, and avoiding scented items in the home.

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