Friend of mine is a nurse who is very sensitive. Was driving a convertible when they drove through a cloud of smoke from some guy burning the Poison Oak on his property. Her face and eyes immediately started swelling, by the time she made it to the ER her head looked like a big, ripe pumpkin....
Years ago I had to take a leak in the woods and that little action cause me considerable pain and discomfort for weeks.
Several years ago during a wild fire in northern California, two firefighters down wind from one section of the fire, breathed smoke from a large patch of poison oak and
subsequently died several days later in the hospital.
Some extremely allergic individuals can get it just by
being downwind on a hot summer day as the wind picks up the oil off the leaves.