Have you ever been in this situation? You just got invited over to a relatives house and then you and a buddy get asked to move a used appliance to a nearby house.
When you get to the house where the used appliance is going, you open the door and a pungent odor hits you! You try to breath normally, but your reluctant to breath at all. You thought it looked safe and you were happy about the whole thing, but now your holding your breath or thinking of putting your shirt up around your head to deal with the odor.