Sunscreen shelves are full of confident promises. The simplest belief they encourage is that picking the right bottle is the whole job. This article tests that belief against what the American Academy of Dermatology says. Start with the day itself, since the EPA's UV Index page is where the daily forecast number lives.
What the American Academy of Dermatology asks about sunscreen
The American Academy of Dermatology puts it as a question: "Do you know that some sunscreens can prevent sunburn, reduce your risk of getting skin cancer, and help prevent early signs of skin aging?"
The key word is "some." The question does not say every sunscreen does all three things. That makes the bottle in your hand worth reading rather than trusting.
Where heat and outdoor work enter the picture
A sunscreen is one part of a day outside. For readers who work outdoors, in Madera where this guide is written or elsewhere in the county, the CDC's page on heat stress and workers covers the other part, which is heat. Neither page replaces the other.
Three benefits to look for on your bottle
The American Academy of Dermatology's sentence names three benefits: sunburn, skin cancer risk and early signs of skin aging. Read the front and the back of the bottle for each of the three. A benefit the bottle never mentions is one it has not claimed.
A second outside source to hold the bottle against
Hold the same bottle against The Skin Cancer Foundation's sunscreen guidance. Two sources reading the same way is a stronger sign than one bottle talking about itself.
Promises on the bottle that no source backs
They agree when the bottle claims what the sources above describe. They part when the bottle promises something none of those sources mentions. Treat that extra promise as unverified until you find a source for it.
What a sunscreen cannot tell you about your skin
A sunscreen does not say what a mark on your skin is. DermNet's page on solar lentigo describes one kind of spot. Whether a spot of yours is that kind is for a clinician to judge, whether you are in Merced, Parksdale or Madera itself.