By law, the two are discussed "with the use of natural gas as a fuel." All that (both in the plant and not the factory.) Need to have "a worker places natural gas" and trained worker ID card.
By law, the second issue to be discussed. "The use of natural gas as a fuel" everywhere (both factory and non-factory) needs to be "workers at gas" trained. And identification operations.
By law, the 2 issues are discussed. "The place is the use of natural gas as fuel." everywhere (the factory and factory) have not needed. "Workers place to use natural gas." Through training and identification study.