The court heard that the workers were asked to remove the asbestos without adequate protection at the Three Crowns pub in Chagford, Dartmoor in January 2010.
The incident occurred when when the refurbishment was being carried out for St Austell Brewery by Cowley's Building and Maintenance and its director, Christopher Reed.
The refurbishment took place without a suitable asbestos survey report, which should have been provided by St Austell Brewery, the magistrates were told.
Asbestos insulation boards
The workers, all employees of Cowley's, uncovered asbestos insulation boards while removing an internal wall.
Reed, the site manager, arranged for a sample of the board to be tested by asbestos specialists. But he also asked the workers to pick-up the debris from the boards.
The workers, who lacked protection, were exposed to the asbestos during the demolition of the wall and the following clean-up operation.
Commenting after the hearing, Health and Safety (HSE) inspector, Barry Trudgian, said: "Multiple failures on site led to significant risks of exposure to asbestos dust to the four workmen.
"Asbestos dust can cause fatal lung diseases and the dangers are well known in the industry. On average, 20 tradesmen die every week from asbestos related diseases.”
20 tradesmen die every week
St Austell Brewery, as the owner of the site, should have provided a full and thorough assessment of the possible presence of asbestos at the Three Crowns.
"Once the asbestos boards were found, the site manager should have stopped the demolition work and reduced the risk of exposure by providing the workmen with a safe system of remedial measures,” said Trudgian.
"All those involved in refurbishment or demolitions must be fully aware of their responsibilities for workers' safety when carrying out their work. This should include following a safe decontamination process, which, depending on severity, could include use of a mask, safe disposal of contaminated clothing and taking a shower."
During the prosecution brought by the HSE, St Austell Brewery Company pleaded guilty to a breach of Regulation 4(3) of the Control of Asbestos Regulations. The firm was fined £5,000 and ordered them to pay £6,295 in costs.
Cowley's Building and Maintenance pleaded guilty to a breach of Regulation 6(1)(a) of the same regulations and was fined £5,000. The company also pleaded guilty to breaching Regulation 11(1)(a) and was fined £7,500.
Reed pleaded guilty to breaching Regulation 11 of the Control of Asbestos Regulations 2006 and was fined £2,500.
To read the HSE guidelines about working safely with asbestos, click here .