woodchippings - gas product

hello

not sure if this is the right part of the forum but here goes...

just shovelled a large pile of conifer woodchippings which had been standing for a week or so and once below the surface, the warm pile started to give off thick clouds of whitish gas. i've since felt quesy. is it toxic? i read that such gas can be ammonia / nitrogen etc but need some hard facts.

quesy feeling could always be down to something else. any help appreciated.