Association accepted that wages could not be further lowered and other approaches must be tried such as production quotas to manage prices. 25% of the workforce was wholly or temporarily out of work by June 1928. Until the mid-1930s the somewhat isolated anthracite mining district in rural West Glamorgan, Brecon and Carmarthen were not covered by the MSWCOA policies, but the pits in this region had many strikes. The owners here were criticized by other coalowners for failing to apply tougher policies such as reprisal, extended lay-offs, and prosecution of unofficial strikers. Silicosis Compensation for growing numbers of certified silicosis cases was causing severe financial problems at some coal companies by the late 1930s. In 1937 the MSWCOA set up a Coal Dust Research Committee to investigate dust-induced respiratory disease. The committee pioneered ways of sampling mine dust, but at the time there was no device capable of accurately sampling dust in the mines. The committee understood that the main cause of health problems was dust particles less than 5 microns in diameter, but thought silica dust was the main threat, rather than coal dust, and therefore argued that protection was only needed for men exposed to silica dust. The chairman of the MSWCOA stated, Last years The MSWCOA became less relevant after the coal mines were nationalized in 1947 and placed under the National Coal Board. The association ceased activity in 1955. The records of the Coal Owners Association are now held by the National Library of Wales and provide a valuable source of information on the history of coal mining and industrial relations in the South Wales coalfields. Two volumes of surveys by Alexander Dalziel, an early secretary of the association, include reports and personal observations on many aspects of mining including underground workings, lamp lighting, ventilation, wages payment, colliery management, miners' housing and stable arrangements at pits. Notes Sources Coal mining in Wales 1873 establishments in the United Kingdom 1955 disestablishments in the United Kingdom Business organisations based in the United Kingdom