The skin's outermost layer, the stratum corneum, acts as a barrier that regulates water loss to the surrounding air. In low-humidity environments—common in Australian homes during winter heating season—this barrier loses water faster than it can be replenished from deeper skin layers, a process called transepidermal water loss. For people with eczema, psoriasis, or simply dry skin, low indoor humidity is a significant and often underestimated aggravating factor.

How Low Humidity Worsens Skin Conditions

Relative humidity below 30 percent increases the rate of transepidermal water loss substantially compared to the 40-60 percent range considered comfortable for skin health. For healthy skin, this manifests as tightness, flaking, and general dryness. For eczema (atopic dermatitis) specifically, an already-compromised skin barrier loses water even faster in dry conditions, and the resulting dryness and cracking can trigger the itch-scratch cycle that leads to flare-ups. Psoriasis plaques similarly become more prone to cracking and irritation in low-humidity conditions.

Central heating, reverse-cycle air conditioning, and wood fires—all common in Victorian, Tasmanian, and South Australian winters—actively lower indoor relative humidity while raising temperature, a combination that is particularly harsh on skin. A room heated from 10°C to 22°C without adding moisture can see relative humidity drop from around 60 percent to under 30 percent, described in detail in our winter indoor air quality guide.

What the Research Shows

Dermatology research consistently associates low ambient humidity with increased skin barrier dysfunction, worsened eczema symptom scores, and higher rates of flare-ups during winter months. Maintaining indoor relative humidity at 40-60 percent is a commonly recommended supportive measure alongside moisturiser use and, where prescribed, topical treatment.

Using a Humidifier as Part of a Skin Care Routine

A humidifier is a supportive environmental measure, not a standalone treatment. It works by slowing the rate at which skin loses moisture to dry air, giving topical moisturisers and any prescribed treatments a better chance to work effectively rather than being undermined by an environment that is constantly drawing moisture back out of the skin.

Place a humidifier in the bedroom, since skin barrier repair happens significantly during sleep and bedrooms are typically where people spend the most consistent hours in a low-airflow, heated or air-conditioned environment. A cool mist ultrasonic or evaporative unit sized for the room (see our sizing guide) running overnight at 40-50 percent target humidity is a reasonable starting point. For children with eczema, follow the same nursery safety guidelines covered in our babies and nurseries guide—cool mist only, positioned away from the cot, with daily cleaning.

What a Humidifier Cannot Replace

  • Moisturiser: A humidifier reduces the rate of water loss from skin but does not replace the barrier function that emollients and moisturisers provide directly on the skin surface.
  • Medical treatment: Prescribed topical corticosteroids, calcineurin inhibitors, or other dermatologist-directed treatments for eczema and psoriasis remain necessary; a humidifier is a supportive environmental measure alongside these, not a substitute.
  • Trigger avoidance: Humidity does not address other eczema triggers such as certain fabrics, soaps, allergens, or stress.

Consistent use matters more than intensity—running a humidifier for a few hours occasionally provides far less benefit than maintaining stable 40-60 percent humidity every night through the dry season. Pair it with daily humidifier cleaning since a poorly maintained unit can disperse mould or bacteria that may aggravate sensitive skin or respiratory conditions rather than helping them.