Contact dermatitis occurs when a sensitive person comes into contact with a particular substance. It is the most common work-related skin condition in the UK, affecting nine per cent of the population, according to the NES. Symptoms can appear anywhere, but commonly develop on the hands and face. Skin that is directly exposed to a particular substance may become red, inflamed, swollen, blistered, dry, thick or cracked. Sufferers may also experience burning or stinging.

There are two types of contact dermatitis:

Irritant contact dermatitis:

Irritant contact dermatitis is the more common type, making up 80 per cent of cases, according to NHS Choices. It occurs when an irritant damages the outer layer of the skin. Symptoms usually appear within 48 hours of exposure, although strong irritants may cause an immediate reaction, while milder irritants may require repeated exposure. Symptoms range from mild dryness and redness to burns and blisters.

Common irritants include:

• Soaps and detergents
• Disinfectants, antiseptics and antibacterials
• Fragrances and preservatives
• Solvents
• Acidic and alkaline substances
• Machine oil
• Cement and powders
• Dust and soil.

People who work in certain occupations are more susceptible than others, including agricultural workers, hairdressers, chemical and construction workers, cleaners, chefs, machine operators and healthcare workers.

Allergic contact dermatitis:

Allergic contact dermatitis occurs when an individual comes into contact with a substance that triggers an allergic reaction. These are called allergens and vary between sufferers. The first time a person comes into contact with an allergen, the body becomes sensitised but produces no obvious reaction. It is only once the exposure to that allergen is repeated that the skin reacts with a red, itchy rash.

Common allergens include:

• Cosmetic ingredients, e.g. preservatives and fragrances
• Metals, particularly nickel and cobalt. Nickel sensitivity is common among people who wear inexpensive, metal jewellery
• Rubber, including latex
• Strong glues, e.g. epoxy resins
• Certain plants, e.g. chrysanthemums.