21.   At one time, they were used in coal mines to provide early warning of deadly methane gas.

22.   All those animals create methane gas, which leads to global warming.

23.   Borzelleri said it may be possible for an engineering solution to be found to prevent potentially explosive methane gases and dangerous toxics like hydrogen sulfide from reaching the surface.

24.   Easter said it is uncommon, but not impossible, for an explosion of methane gas to occur outdoors, because the gas is easily dispersed.

25.   Eurogas controls concessions in Poland to extract methane gas from coal beds.

26.   Flatulence is methane gas produced by bacteria that help break down food and other organic products.

27.   Gas company inspectors found levels of methane gas so high that they worried an explosion could occur if they went much higher.

28.   High levels of volatile methane gas meant the hunt had to be delayed.

29.   It might be expected that digesting all that fiber would produce large amounts of methane gas.

30.   It remains unclear if the complex will be completed because of explosive methane gas pervading the site and other environmental problems.