Editor's note: This story is on the 2015 sunscreen report. For information on the 2016 report, click here.

May 14, 2015 -- Nearly a third of sunscreens tested by Consumer Reports fell short of the promised SPF protection, missing the mark by anywhere from 16% to 70%, according to the organization’s annual sunscreen report.

The report also expressed concerns about so-called “natural” sunscreens and claims of broad-spectrum protection against both UVB and UVA rays.

Fifteen of 34 sunscreens tested earned a spot on the “recommended” list.

"We tested more this year than we have in our previous tests," says Trisha Calvo, deputy editor of health and food at Consumer Reports. Last year, 7 out of 20 tested sunscreens were recommended.

The testing is extensive and includes having volunteers soak in water after applying sunscreen, then exposing them to ultraviolet rays to see if their skin reddens. In a statement, the Personal Care Products Council, an industry group that includes sunscreen makers, took exception to some of Consumer Reports’ findings and the testing process.

The full report is published in the July issue of the magazine.