Most accidents are preventable.The problem with oilfield accidents it that they can be lethal.Two Barton County men died of asphyxiation Monday from the presence of hydrogen sulfide gas, a by-product from the production of oil and natural gas. Hydrogen sulfide causes respiratory paralysis and is highly toxic.Dave McEndarffer has worked in the gas detection industry for 28 years. He works with RKI Instruments Inc., a gas detection company in Overland Park.