system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When momentarily walking past fumes (exhaust, tar, etc) is it better to breathe normally or to restrict your breathing for a short period (thus reducing oxygen intake)?

I walk to work and follow a busy road. It's not like walking in a park where the air is 'fresh.' Is it damaging or beneficial to restrict my breathing when beside several lanes of idling vehicles?
gpt
Hold it. There isn't harm in short periods without breathing, so the down side is nil. The stuff you're breathing probably isn't going to hurt you if it's just a whiff, but there's more potential harm from it than from held breath.