Airborne Contact Dermatitis

Airborne contact dermatitis is an allergic or irritant dermatitis caused by airborne particles, vapours or aerosols that deposit on exposed skin. It mainly affects the face, neck and forearms, and often mimics photodermatitis.

It is most frequent in agricultural, horticultural, forestry, construction and chemical workers, and in people exposed to plants and household sprays. Many cases are underdiagnosed because the exposure is not obvious.

Causes include plants (Compositae such as ragweed and chrysanthemum, Parthenium hysterophorus, sesquiterpene lactones), pesticides, epoxy resin and acrylate vapour, wood dust, fragrance sprays and rubber chemicals. Drug particles and aerosols from handling medication are an occupational cause in healthcare workers.

Pathophysiology.

Particles settle on exposed skin and mucosa and act as haptens, triggering type IV hypersensitivity in sensitised people. Non-allergic irritant reactions occur at high concentrations. Light exposure can coexist, and Parthenium disease may progress to chronic actinic dermatitis.

• Eczema of the eyelids, face, neck (V area), ears and forearms, with involvement of the submental area and behind the ears, which differs from photodermatitis.
• Periorbital swelling, itch, scaling and lichenification, with worsening at work and improvement on holidays.
• Sometimes accompanied by conjunctivitis or rhinitis.
• Chronic disease can spread widely and become erythrodermic.

Red flags.

• Erythroderma or exfoliation.
• Marked facial oedema with systemic features.
• Chronic seasonal disease with light sensitivity, suggesting chronic actinic dermatitis.

• Occupational and environmental history with exposure timing and the distribution of involved and spared skin.
• Patch testing with the baseline series, sesquiterpene lactone mix, Compositae mix, plant series, epoxy resin, acrylates, fragrance and workplace samples.
• Photopatch testing and phototesting when photosensitivity is suspected.
• Skin biopsy is rarely needed.

Differential diagnosis. Photodermatitis, seborrhoeic dermatitis, atopic dermatitis, rosacea, dermatomyositis, lupus erythematosus and direct contact dermatitis from handled materials.

• Identify and remove the airborne agent. Use enclosed processes, ventilation, protective clothing, face shields and respirators at work.
• Emollients and avoidance of irritants.
• Potent corticosteroid (betamethasone valerate 0.1%) once daily on the body for 1 to 2 weeks, and moderate potency (clobetasone butyrate 0.05%) on the face for up to 2 weeks.
• Tacrolimus 0.1% ointment twice daily on the body, or 0.03% on the face, as maintenance.
• Prednisolone 0.5 mg/kg/day (usually 30 to 40 mg) for 5 to 7 days for severe flares.
• Chronic disease, including Parthenium dermatitis: azathioprine 1 to 3 mg/kg/day after thiopurine methyltransferase testing, or ciclosporin 2.5 to 5 mg/kg/day in two divided doses, with monitoring.

Monitoring. Review at 2 to 4 weeks. Monitor full blood count and liver tests on azathioprine, and blood pressure and creatinine on ciclosporin.

Referral and escalation. Refer for patch testing, occupational medicine input and for chronic or refractory disease.