HEALTH AT WORK

Industrial Health

Roofer Developing Skin Rash on Forearms After Laying Bitumen Felt in Summer Heat

19 September 2026 · Health at Work · AI-assisted draft

Photo: Daniel & Hannah Snipes / Pexels

If you are a roofer who has noticed red, itchy or blistered skin on your forearms after a summer of laying bitumen felt, you are not alone and you are not imagining it. What you are experiencing has a name, a mechanism and a trajectory — and the sooner it is taken seriously, the better the outcome. This article explains exactly what is happening to your skin, why summer heat makes it significantly worse, and what both workers and employers must do about it.

What Bitumen Actually Does to Skin — and Why Heat Changes Everything

Bitumen is a dark, viscous petroleum derivative used in roofing felt, waterproof membranes and modified bitumen sheets. At ambient temperatures it is relatively stable, but in summer heat — and especially when torch-applied or hot-poured — it releases volatile polycyclic aromatic hydrocarbons (PAHs). These compounds are the key hazard. They settle on exposed skin, penetrate the outer layers and trigger two distinct types of reaction depending on the individual and the duration of exposure.

The first reaction is phototoxic dermatitis. PAHs absorbed into the skin become chemically activated by ultraviolet radiation — exactly the UV that is most intense during summer roofing work. The result is a burn-like rash that appears on the sun-exposed surfaces of the forearms, the back of the hands, the neck and sometimes the face. It looks like severe sunburn: redness, swelling, blistering and peeling. It is not caused by the sun alone, and it is not caused by bitumen alone — it is the combination, which is why the same worker may have no visible reaction in winter and a serious one in July.

The second reaction is allergic contact dermatitis, which develops after repeated sensitisation. Once the immune system has been primed by bitumen components — and this can take months or years — even brief low-level contact triggers an inflammatory response: intense itching, red papules and vesicles, often spreading beyond the contact area. Unlike phototoxic reactions, this one does not require sunlight and does not go away when exposure stops. It is a permanent change in immune reactivity.

Who Is Most Exposed, and Which Tasks Carry the Greatest Risk

Any roofer handling bitumen felt is at some level of risk, but the exposure is not uniform. Workers who torch-apply modified bitumen sheets face the highest dermal and vapour exposure because heating the material releases far more PAHs than cold application. Those who unroll and cut bitumen felt without gloves — believing it is a minor, short task — accumulate significant skin contact over a working day. Labourers who carry and position rolls, sweep bitumen debris or clean tools contaminated with hot bitumen are also exposed, even if they are not the primary layer.

Summer conditions compound the risk in several ways. Sweating increases skin permeability, allowing PAHs to penetrate more readily. Heat causes workers to remove long sleeves and gloves, dramatically increasing the surface area of exposed skin. Strong UV radiation turns absorbed compounds phototoxic. And the pace of warm-weather construction often means breaks are shorter and PPE compliance drops.

Recognising the Rash — Early Signs That Are Easy to Miss

The earliest signs are easy to attribute to ordinary sunburn or dryness: mild redness across the forearms, slight tightening of the skin, occasional itching at the end of a hot day. Many workers treat these with moisturiser and return to work the next morning without reporting anything. This is where the opportunity for early intervention is lost.

Within days to a few weeks of continued exposure, the picture becomes clearer and more serious. Blisters may form on sun-exposed skin, particularly on the forearms between the glove cuff and the sleeve. The skin may darken — hyperpigmentation is a recognised feature of chronic bitumen-related phototoxic dermatitis and can persist for months after exposure ends. In cases where allergic sensitisation has developed, the rash spreads to areas not in direct contact with bitumen: the inner elbows, the upper arms, even the torso. The itch becomes severe and disrupts sleep.

Later-stage presentation, seen in workers who have continued working through symptoms for months or years, includes chronic thickening and scaling of forearm skin, recurrent infected eczema from broken skin, and in some documented cases, changes that require specialist dermatological investigation given the known carcinogenicity of PAHs. Any non-healing lesion, ulcer or unusual skin change on a roofer's exposed skin warrants prompt medical review.

What Employers Are Required to Do

Under occupational health regulations in most jurisdictions, employers have a legal duty to assess and control exposure to hazardous substances before work begins — not after workers develop symptoms. For bitumen work, this means conducting a formal skin exposure risk assessment that identifies which tasks cause dermal contact, which workers are affected and what controls are in place.

Employers must provide suitable PPE — specifically, nitrile or neoprene chemical-resistant gloves that are long enough to cover the forearm gap, UV-protective long-sleeved workwear and, where vapour exposure is significant, appropriate respiratory protection. They must also ensure that pre-placement and periodic health surveillance is carried out for workers regularly exposed to bitumen, so that early skin changes are identified before they become serious. Health surveillance in this context means more than a tick-box questionnaire: it should include visual skin inspection and a structured interview about symptoms, ideally conducted or overseen by an occupational health professional.

Employers who dismiss a roofer's rash as 'just sunburn' or tell workers to 'toughen up' are not only failing their duty of care — they are allowing a preventable condition to progress to one that may permanently end a worker's ability to do their job.

Practical Controls That Actually Work — and Ones That Do Not

The hierarchy of controls applies here as it does everywhere. Elimination — removing bitumen entirely — is rarely practical in roofing, but substitution is increasingly possible: cold-applied liquid waterproofing membranes and self-adhesive peel-and-stick systems eliminate torch application and dramatically reduce PAH release. Where hot bitumen cannot be substituted, engineering controls should come next: mechanised application equipment that reduces hand contact, portable ventilation to disperse vapours at the point of work, and scheduling hot bitumen work for early morning when UV index is lower.

At the personal protection level, the combination of chemical-resistant gloves with extended cuffs and close-woven UV-protective long sleeves is essential — not optional. Standard cotton work shirts provide almost no UV protection and absorb bitumen splashes against the skin. Workers should apply a barrier cream to exposed skin before work and cleanse thoroughly at the end of the shift using an appropriate skin cleanser, not solvent, to remove bitumen residue. Solvents strip the skin's natural barrier and worsen dermatitis.

What does not work reliably: ordinary nitrile examination gloves, which are too short and too thin for prolonged bitumen contact; sunscreen applied over contaminated skin, which seals PAHs against the surface rather than protecting against them; and verbal reminders to 'keep covered' without providing clothing that workers can actually work in during high temperatures. If PPE is uncomfortable in summer heat, workers will remove it — the answer is breathable UV-rated workwear, not hotter conventional alternatives.

What a Worker Should Do If the Rash Has Already Started

Do not wait for a scheduled appointment if blisters, spreading rash or severe itching have already appeared. Report the symptoms to your employer or line manager the same day, as this creates a record and triggers the employer's duty to respond. Seek medical advice promptly — ideally from a practitioner with occupational health experience who understands bitumen exposure, rather than one who may treat the presentation as ordinary eczema and miss the occupational cause.

Ask specifically for a referral to an occupational skin specialist or dermatologist if symptoms do not resolve within two to three weeks of reduced exposure, if blistering recurs, or if the rash spreads despite PPE improvements. A patch test can identify whether allergic sensitisation has occurred; if it has, this is clinically significant information that affects your ability to continue working with bitumen products and must be documented.

Keep a record of the tasks you were doing in the days before symptoms appeared, the PPE you were wearing and the weather conditions. This information is essential for any occupational health assessment and for any future claim or compensation process if the condition becomes disabling.

The Misunderstanding That Makes This Worse

The most damaging misconception about bitumen rash is that it is the same as sunburn and will resolve on its own. Some cases do — the mild phototoxic reactions that follow a single day of unprotected exposure in a worker who has not yet been sensitised often fade within a week. But returning to work the following week in the same conditions, with the same skin still recovering, accelerates sensitisation and increases the severity of subsequent reactions. Each exposure episode in a sensitised individual is worse than the last, not better.

A second common mistake is attributing the rash to a new brand of sun cream, washing powder or food rather than the occupational exposure. By the time a worker has spent months investigating non-occupational causes, the window for early intervention has closed and the skin change may be permanent. If the rash appears on forearms, worsens in summer, and correlates with days spent laying bitumen felt, the occupational cause should be the first hypothesis investigated — not the last.

Health at Work provides occupational health assessments, skin surveillance programmes and employer risk assessment support for construction and roofing trades. Early referral consistently produces better outcomes than waiting until symptoms become severe.