Today we went to the Big Pit National Coal Museum in South Wales. From 1880 to 1980,  Big Pit was a working coal mine, but now is considered a National Museum of Wales and dedicated to preserving the Welsh heritage of coal mining. Big Pit has over 20 miles of underground mining paths, but nowadays only about 1 mile of it is open to the public for tours, like the tour we did today. The whole place is not fully open to the public because, due to British regulations, the mine needs to be checked for dangerous gas levels every 4 hours, so it would be impractical to have to check all 20+ miles of underground mines every 4 hours.

The main concerning gases found underground in the coal mine are methane and carbon monoxide and there are various ways in which they check for these gases both in the present and past.

To check for carbon monoxide, miners and/or rescue crews coming underground would carry small bird cages with canary birds in them. The canaries would get affected by carbon monoxide faster than humans would, so if a miner or rescuer noticed their canaries were acting strange or losing consciousness, it would give them enough time to get out of the area with toxic levels of carbon monoxide. The Big Pit still uses canaries and keeps them upstairs to use in walks around the mine to check for gas levels (see picture below). However, nowadays, there is more advanced and specialized electronic equipment that many rescue crews carry that have the ability to detect dangerous levels of carbon monoxide.

All miners in the past as well as tour guides and the general public that go on tours underground carry emergency respirators on their belt in case of carbon monoxide exposure. If carbon monoxide is noticed, people can put on the respirators, which given them enough air for an hour, plenty of time to find their way out of the mine.

Methane is another one of the dangerous gases found in mines. Methane is released in the coal dust when miners dig for coal in the walls or ground. It is an extremely flammable gas, which is why everyone going underground for tours has to leave all electronics and lighters at the entrance so as not to have anything that could possibly cause a spark and ignite any methane in the air particles.

In the past, miners used Davy lamps, which were lanterns with a flame enclosed inside a mesh screen, which acted as a flame arrestor (allowing air to pass through the mesh, but preventing the flame from propagating through and igniting anything outside the mesh). This lamp also was used to detect the presence of gases. If flammable gas, such as methane, was present in the air, the Davy lamp would burn higher with a blue tinge. It was also used to detect levels of carbon dioxide. Many of the tour guides, who were previous miners, still prefer this type of method to check gas levels rather than using electronic detectors.

Thanks for reading!

Bella Calabrese