Silicosis and Welsh Slate Quarrymen: The Hidden Cost

What caused silicosis in Welsh slate quarrymen?

Slate work was not one single job. Stone was extracted, moved, cut, sawn, split, trimmed and finished. Drilling and blasting disturbed the rock at the working face. Saws and dressing machinery could release more dust as blocks became usable slabs and roofing slates.

The Welsh word chwarel means quarry. A quarryman is a chwarelwr, with chwarelwyr as the plural. These words are useful because not every slate worker was a miner. Open quarries and underground slate mines had different layouts and ventilation, although dusty tasks could exist in both.

Workers could see much of the coarse dust that settled on surfaces and clothing. The most dangerous respirable particles are much smaller. They can remain airborne and travel deep into the lungs. A clean-looking area is therefore not proof that exposure is controlled.

Slate itself is not chemically identical from one site or layer to another. The Health and Safety Executive's guidance on silicosis says slate can contain up to 40 percent silica. That is an upper figure, not a fixed composition for every Welsh quarry.

The phrase llwch llechi means slate dust. It sounds simple, but it covers particles of different sizes and compositions. For occupational health, the critical questions are which particles a worker breathes, how concentrated they are and how long exposure continues.

What could slate dust do to the lungs?

Respirable crystalline silica can reach the smallest parts of the lungs. The body's response can produce inflammation and scarring. As that damage accumulates, the lungs become less able to transfer oxygen and a worker may experience cough, breathlessness and reduced physical capacity.

The Health and Safety Executive identifies silicosis, chronic obstructive pulmonary disease and lung cancer among the risks linked with respirable crystalline silica. People who have silicosis are also at increased risk of tuberculosis, although tuberculosis remains a separate infectious disease.

Disease may become apparent after years of work or after a worker has left the industry. This delay made compensation particularly difficult when a former employer had closed, records were limited, or a diagnosis did not fit the rules then in force.

What did medical studies of north Wales slate workers find?

One early investigation was published by T. W. Davies in 1939. It examined 117 slate quarry miners in the Blaenau Ffestiniog area and reported radiographic signs in one of three stages in 62.4 percent of the group. It also identified a serious relationship with tuberculosis and called for wider environmental and radiological investigation.

That percentage must be handled carefully. The study involved a selected group of 117 workers, not every slate worker in north Wales. Its X-ray categories and diagnostic practice belong to the medicine of the 1930s. It is evidence of a major problem within the group studied, not a valid prevalence estimate for an entire industry across all periods.

A much larger study, Effects of exposure to slate dust in North Wales, was published in 1980. Researchers examined 725 exposed workers and former workers and compared them with 530 unexposed men from the same broad area. Pneumoconiosis was found in about one-third of the exposed group. Ten percent had category 2 disease or higher, the level then relevant to compensation.

The researchers also reported more respiratory symptoms and reduced lung function among exposed men. Radiological changes suggesting healed tuberculosis were particularly common among older workers. Again, these figures describe the study cohort and the diagnostic system used at the time. They should not be converted into a claim that one-third of every Welsh slate workforce had the same disease.

The long-term picture became clearer through a later follow-up. A 24-year cohort study published in 2005 followed 726 slate workers and 529 age-matched controls from 1975 to 1998. After adjustment, the hazard ratio was 1.24 for death from all causes and 1.85 for respiratory death among the slate workers. The authors considered slate-dust exposure the likely explanation for the excess, while also warning that death certificates did not always record pneumoconiosis accurately.

Why did recognition take so long?

The history was not a simple march from ignorance to discovery. Workers' experience, medical interpretation, industry interests and compensation rules did not always point in the same direction. Diagnostic technology was changing, and specialists disagreed about what an X-ray showed and how dust-related disease should be classified.

A revealing example appears in a 1939 parliamentary debate on north Wales slate quarrymen. The responsible minister said an expert inquiry had found no evidence of silicosis in open quarries, while investigations in underground slate mines were continuing. That statement records the government's position at that moment. Later studies found substantial pneumoconiosis among slate workers, so the 1939 statement cannot be treated as the final medical answer.

The open-quarry distinction also affected the possible scope of official recognition and compensation. A finding confined to underground conditions or particular jobs would have narrowed the workers covered. Yet workers moved between tasks, and the production process included dusty mills and dressing sheds as well as extraction sites.

It is still too broad to say that every quarry owner or doctor denied the danger. Responses differed across people and periods. Documented official claims sometimes minimised the risk, while later research demonstrated a serious occupational-health problem.

How did quarry communities campaign for recognition?

By the 1970s, the issue had become a community campaign as well as a medical debate. A silicosis campaign banner preserved by Museum Wales records organising by slate communities on behalf of affected workers and widows. The campaign intensified from 1974, and a dedicated committee was operating by the middle of the decade.

Families experienced the disease through reduced earning capacity, practical care and bereavement. Widows were central because compensation rules affected dependants as well as living workers. The campaign therefore challenged more than a medical definition. It asked who should bear the cost when an occupational disease appeared slowly and the company connected with an exposure was no longer available to sue.

The Pearson Commission reported in 1978 but did not recommend the special scheme campaigners wanted. Protest continued, including a demonstration at Llanberis in July 1978. The eventual legislation covered several dusty industries, but the long campaign in the slate communities of north Wales formed an important part of the political pressure behind it.

The surviving banner is valuable evidence of that collective action. Its online image is available by permission rather than under an open reuse licence, so it is linked here as a museum record rather than reproduced in the article.

What did the 1979 compensation law change?

The Pneumoconiosis etc. (Workers' Compensation) Act 1979 created government-funded lump-sum payments for eligible sufferers and certain dependants. For a living claimant, the original conditions included payable disablement benefit, every relevant employer having ceased business, and no damages action or compromised claim.

This was important for slate workers whose disease might emerge years after exposure. It offered a route where an ordinary damages claim was no longer practical. The scheme was not unlimited, and eligibility depended on the statutory rules, but it addressed a gap that had left seriously ill workers and families without an effective defendant.

The Act did not recognise silicosis for the first time. British compensation arrangements for pneumoconiosis had developed over earlier decades. Its specific contribution was the lump-sum scheme for eligible sufferers and dependants who could not recover civil damages. That distinction prevents a powerful campaign history from being attached to an inaccurate legal claim.

Current Industrial Injuries Disablement Benefit guidance still lists the sawing, splitting or dressing of slate under prescribed disease D1. The wording connects modern administration to the particular tasks that created dust in the historical industry.

Why does this history still matter?

Silicosis is not only a disease of museum displays and old quarries. The Health and Safety Executive continues to identify work with stone, rock and slate among activities where respirable crystalline silica must be controlled. Modern prevention depends on suppressing dust at source, isolating processes, using effective extraction and respiratory protection where required, and monitoring workers' health.

Those controls belong to today's regulatory system and should not be projected backwards as if historical quarries were measured by the same methods. Their value lies in showing that the hazard is now understood well enough to prevent exposure, not in supplying false precision about conditions a century ago.

The history also changes how we look at Welsh slate. The material remains an extraordinary part of Wales's landscape, architecture and industrial heritage. Respecting that achievement means remembering the chwarelwyr whose skill produced it and the families who carried the consequences when dust damaged their health.

Taken together, the three studies document radiographic disease, pneumoconiosis and excess respiratory mortality among the workers examined. Campaigners then helped secure a compensation route for people who could not obtain damages from employers that had ceased business. Those findings reveal the hidden cost behind the finished slate.