he is not eating the right foods,try to get him to eat more fruits and fresh veg.the gas is from rotten bacteria in his intestines.he might need a colon cleanse product to end the methane gas.and yes,it is bad for the environment,i read that if people ate better it would be better for the environment.not enough to make you sick.just gross
You need to specify.. gas from a car? or gas from you know where?
Wear an oxygen mask when you are around him.
Find out what causes the gas and go from there. He definitely has irregularity, but it may be reversible. It is not bad for the environment and it will not make you sick unless you're hypersensitive.