Afon Meirchion Cave (Lower) - grid ref: SJ 022 694
During trip on Monday 12th July 2010, Gas Alarm went off with O2 level at 19.2% at start of first sand crawl. H2s, CO and H2S were all zero.
2 other individuals who had already passed through the crawl and proceeded approx another 30m returned ok. 1 member reported slight headache, other member had no side effects. No reading were taken further into the cave than the first sand crawl, but general concusses was that the levels were well below 19 further in the system.
Sand had been disturbed and the system was dry at the time.