All of those people were in contact a month after, and we've heard over and over how volatile it is. That chart you posted, if I'm reading it correctly, says for anesthesia it takes a lot (8,000-10,000 ppm). But I also remember the testimony during the trial about the heavier than air stuff, and since what didn't dissipate into the air would quickly vaporize in that heat, the vapors would basically be settled into the lowest area( the tire well) after a short time. The residuals remained but enough gas to affect someone would be gone fairly quickly.
I wasn't talking about CA cleaning the trunk up a bit...FCA evidently used paper towels to wipe off some of the grave wax, so assuming she may have vacuumed a few flies, etc. after she dumped the body isn't such a leap, IMO