Chemical ingredient formulations (most commonly used by sunscreen makers are: avobenzone, oxybenzone, benzophenone, octyl methoxycinnamate, octyl salicylate, para-aminobenzoic acid (PABA), methyl salicylate, padimate A, Padimate O, and homosalate) must be applied 30 minutes prior to going outside because that is how long it takes for those ingredients to become effective.
Don’t be fooled by “waterproof” and “water resistant” – there is NO SUCH THING.
ALL sunscreens must be reapplied every 90-120 minutes while outside or immediately after swimming or intense sweating to keep their efficacy. SPF 15 is said to be enoughfor daily wear for the average person. SPF 30-50 is recommended for people with sun-related medical problems. Or, for those who spend longer hours or days in the sun.
Spray cans are not effective in providing a thorough, precise application as a regular tube of sunsccreen. Spray cans provide an uneven application therefore increasing the likeliness of burning.
Cleanse In Truth 
I have read that several of the sunscreen formulations in this posting can actually break down when exposed to sunlight and be a source of free radicals which can damage the skin, causing premature aging and an increase in the chance of skin cancer development. Because of this I avoid sunscreens with those ingredients. Do you know if there is a place where I can find a list of these unsafe and potentially damaging ingredients?
Hi Kelsey,
Sadly, there are several chemical formulations of sunscreen (just like any other skincare product). If you go to environmentalworkinggroup.org/net? you can view all of the potentially harmful ingredients in sunscreens- there are many unfortunately. On a lighter note, if you find a sunscreen with only physical blocks, i.e. titanium dioxide and zinc oxide, these are non-chemical sunscreens. The best and safest SPF I’ve ever used is by Colorescience. It is a mineral based powder spf only formulated of those two physical sunscreens. It’s genius and very effective – I provide the retail product for my clients. This is our best bet. It is a catch 22 because UV rays alone (the sun) cause free radicals in our body and in our skin which leads to the breakdown of healthy body and skin cells, increasing the possibility for cancer causing cells to develop. You bring up a great point. Sunscreen use has increased astronomically over the last couple decades due to catchy advertising but skin cancer has not decreased in the least. Hmmm.