With the summer almost here, people will be heading to the beach with their SPF 30 sunscreen in hand, and completely unaware of the dangers that face them.

Sunscreens aren’t all they’re cracked up to be. For one thing, many of them don’t protect you from ultraviolet A light, which is a significant cause of skin cancer, and Consumer Reports has found that yet again, many of them don’t live up to the SPF claims on their labels.

Many times, when we don’t get the protection we need from sunscreen, it’s our fault because we fail to use enough sunscreen, we don’t apply it correctly or evenly on our bodies, or we don’t reapply it after it’s washed off. But many times it’s because sunscreen manufacturers are falsely claiming how much SPF a sunscreen has, and Consumer Reports said that it recent tests, 43 percent of sunscreens didn’t have the SPF their label claims.

And Consumer Reports has noticed this pattern for the past four years. About half of sunscreens each of those years didn’t reach the SPF advertised on their label.

“We crunched the data from four years of our sunscreen testing—104 products in all—to see how well sunscreens in general protect you against the sun’s UVB rays,” the statement reads. “Our findings were troubling, especially when it came to mineral products, often called “natural” sunscreens—those that contain only titanium dioxide, zinc oxide, or both as active ingredients. The Food and Drug Administration (FDA) doesn’t routinely test sunscreens; it requires the manufacturers to test their products. But in most cases the companies don’t have to submit their results, just keep them on hand in case the FDA asks to see them. What’s more, companies only have to test a sunscreen on people when a product rolls out or is reformulated.”