Low-humidity dermatosis from car heaters

Higher prevalence of dry symptoms in skin, eyes, nose and throat among workers in clean rooms with moderate humidity

OBJECTIVE

To determine whether working under relative humidity (RH) around 55 +/- 5% may lead to dry symptoms among workers in tropical regions.

METHODS

We recruited 3,154 Taiwanese workers who had no history of skin diseases and compared dry symptoms between clean room workers (RH around 55 +/- 5%) and other workers (RH around 65 +/- 5%).

RESULTS

Clean room workers had higher prevalences of dry symptoms of the eye (odds ratio [OR]=1.62, 95% confidence interval [CI]: 1.40 to 1.86), nose and throat (OR=2.15, 95% CI: 1.66 to 2.79), and skin (OR=1.46, 95% CI: 1.23 to 1.73). In clean room workers, however, dry skin symptoms affected the palms (OR=1.72, 95% CI: 1.24 to 2.39), which are covered by gloves, more frequently than the face (OR=0.65, 95% CI: 0.45 to 0.94), which is exposed to the room air. We found working in clean rooms (adjusted OR [AOR]=1.38, 95% CI: 1.08 to 1.77), 24 to 30 yr of age (AOR=0.78, 95% CI: 0.62 to 0.99), family history of atopic diseases (AOR=1.75, 95% CI: 1.37 to 2.25), and skin moisturizer use (AOR=1.64, 95% CI: 1.30 to 2.06) were independent predictors of skin symptoms. In addition, working in clean rooms was an independent predictor of dry eye (AOR=1.30, 95% CI: 1.06 to 1.60) and dry nose and throat (AOR=1.70, 95% CI: 1.28 to 2.26) symptoms.

CONCLUSIONS

Whereas the humidity in such working environments is not very low, for workers living in a high humidity environment, the relatively low humidity may still cause dry symptoms of the eye, nose, and throat.

Irritants in combination with a synergistic or additive effect on the skin response: an overview of tandem irritation studies

Sodium lauryl sulfate (SLS) has often been chosen as a model for irritant contact dermatitis (ICD) to study the effect of irritants in combination (1-14). Recently 'tandem', or sequential, exposures with SLS have been performed to study the mechanism of skin barrier impairment in ICD (1-6, 15). The assessment of reactions have been documented with visual scoring, transepidermal water loss (TEWL), skin colour reflectance measurements, skin blood flow; among which TEWL has been noted as the most sensitive value (16). The matched control groups were treated with either a single exposure to a single irritant or in tandem with the same irritant repeatedly. Synergistic and additive effects have been reported for various tandem pairs of irritants, however, the mechanism for both remains unclear. The results of tandem irritation studies were evaluated to define and investigate the responses produced and deduce a possible mechanism of action. Clinical ramifications, albeit complex, are discussed.

Air flow at different temperatures increases sodium lauryl sulphate-induced barrier disruption and irritation in vivo

BACKGROUND

Combined exposure to dry climatic conditions and local heat sources together with detergents represents a common workplace situation. These conditions may support the induction of chronic barrier disruption leading subsequently to irritant contact dermatitis (ICD).

OBJECTIVES

To test the irritant and barrier disrupting properties of air flow at different temperatures and velocities.

METHODS

Using noninvasive biophysical measurements such as transepidermal water loss (TEWL) (TM 210; Courage & Khazaka, Cologne, Germany) we assessed the effects of short-term exposure to air flow at different temperatures (24 degrees C and 43 degrees C) in combination with sodium lauryl sulphate (SLS) 0.5% on the skin of 20 healthy volunteers in a tandem repeated irritation test. Chromametry was used to control the accuracy of the SLS irritation model.

RESULTS

In our study air flow alone did not lead to a significant increase in TEWL values. Sequential treatment with air flow and SLS led to an impairment of barrier function and irritation stronger than that produced by SLS alone. The two different air flow temperatures led to different skin temperatures but had no influence on permeability barrier function.

CONCLUSIONS

Warm air flow has an additional effect on the SLS-induced barrier disruption in a tandem irritation test with sequential exposure to SLS/air flow. This combination is suspected to promote ICD in workplace and household situations, especially in short-term applications as tested in our model.