Airborne formaldehyde causes skin barrier dysfunction in atopic dermatitis

It remains to be elucidated whether exposure to air pollutants aggravates atopic dermatitis (AD).

This study aimed to evaluate the effects of exposure to formaldehyde for 1 h and 2 h on skin barrier function in both the control and the AD groups.

In 41 patients with AD and 34 healthy children, a provocation test was performed in which two different areas of normal-appearing skin on the forearm were stimulated with airborne formaldehyde at 500 μg m(-3) or placebo for 2 h. We measured transepidermal water loss (TEWL) and skin pH, and calculated the percentage change from baseline.

Exposure to formaldehyde increased TEWL in the control group [P < 0·001; median of difference 1·4; interquartile range (IQR) 0·9-1·6] and in the AD group (P < 0·001; median of difference 2·5; IQR 2·0-3·6). The percentage change of TEWL after formaldehyde exposure in the AD group was higher than in the control group (P < 0·001), whereas exposure to placebo showed no differences between both groups. The AD group also demonstrated a higher percentage increase in skin pH after exposure to formaldehyde than the control group (P < 0·001).

Short-term exposure to formaldehyde causes skin barrier dysfunction in both healthy children and children with AD, and this effect is more prominent in children with AD.