I think I asked this before, but looking in search I’m not seeing it.
Anyway, with car interiors reaching 170F or so when its hot out, what forms of anti-tick/mosquito spray as well as sunscreen could a person store in their car, so that the active ingredients do not decompose or become ineffective due to the heat? I like keeping a bottle of each in my car in case I end up driving somewhere to go hiking, but if leaving it in the car for months on end causes the heat to destroy the active ingredients theres no point.
Is DEET stable enough to survive 170F temperatures? I believe someone once said zinc oxide sunscreen could survive that level of heat but I don’t remember exactly.
I’d assume so too. But I had an instance where I bought some sunscreen (forget the SPF, probably 30 or so) that I left in my car for months. When I went to use it, It was totally ineffective. I was only out in the sun for 2 hours but I had a really bad sunburn on the back of my neck where I applied it. I assumed the car heat destroyed the ingredients.
You don’t have to store sunscreen in a refrigerator, but you should try for a cool area. According to the Sun Protection Guide, sunscreen formulas don’t like temperatures beyond 77 degrees, as heat can cause formula instability and cause it to separate.
Sounds like a good question for a pharmacist (among my favorite people, unsung heroes). They know every thing about substances you put on your body as well as the temperature range at which said compounds need to be kept.
As a nurse who has to worry about such things, I will be surprised if there are repellents and sunscreens out there that can retain effectiveness at the temperatures found in cars. You could try reading the fine print on the packaging, it probably states the temperature range. Also note the expiration date, once sunscreen is overage it may look ok but won’t be protective enough. I have learned to write the exp. date in Sharpie on the container, saves wondering “how old is this?”. But still, find a pharmacist, they like a chance to strut their stuff since they studied long and hard.