Do we really feel the sun more strongly these days? Is the ozone layer truly thinner so I’m exposed to more UV than a few decades ago?

— Stuart Ridgway, senior product manager, The Washington Post

Can you spot the oncoming freight train? We certainly couldn’t. This deceptively innocent query led us down a warren of rabbit holes that left us questioning everything we thought we knew about sun protection.

Stuart’s also right about the sun-protection-factor arms race. In 2000, most sunscreeners used SPF 15 or below. By 2015, more than three-quarters of them reached for SPF 30 or higher.

Meanwhile, the answer to his basic question of whether the sun had become sunnier was reassuringly straightforward — even uplifting. If anything, we’re exposed to less of the sun’s ultraviolet waves than we were a few decades ago, the Environmental Protection Agency told us.

That’s because the UV-blocking, bazillion-SPF ozone layer grows thicker every year thanks to one of the environmental movement’s great success stories: the treaty that phased out chlorofluorocarbons and their ilk starting in 1989. You’re still getting more UV than you did in the 1950s, but the National Oceanic and Atmospheric Administration estimates we’ll be back to full ozone protection by the middle of this century.

Who uses sunscreen? Women are more than twice as likely as men to always wear it when they go out in the sun for over an hour, and White people are almost four times more likely to always wear it than their Black friends. But sunscreen use has risen across the board.

Seemal Desai, president of the American Academy of Dermatology (AAD), attributed the shift to “really good information being put out by organizations like the American Academy of Dermatology that advocate for sun protection, skin cancer education, skin cancer awareness.”

But when we looked to see how American perceptions of solar danger had changed, we spotted a fly in the ointment.

About 19 percent of Americans say that if they avoided the sun for months, then spent an hour basking in direct rays without protection, nothing would happen to them. That figure was 15 percent in 2015 and 12 percent in 2000.

Self-reported sun resistance has risen fastest among Black and Hispanic Americans as well as young men in general. But even White and older Americans have become slightly more likely to report that they’re impervious to insolation.

Are they right? Uh, for the most part, no, said Rebecca Hartman, chief of dermatology at VA Boston Healthcare System and assistant professor of dermatology at Harvard Medical School and the affiliated Brigham and Women’s Hospital.

Hartman explained that it’s a stretch to say “nothing” will happen if you go out into the sun. Unless you happen to have the darkest skin type (which applied to just 9 percent of Americans, according to an analysis of photos of 2,691 people’s skin taken in 2003 and 2004 as part of the National Health and Nutrition Examination Survey).

“For most people, something happens,” Hartman said. “It’s not necessarily sunburn, but they get darker, more tan, like even someone with naturally darker skin.”

So why do a growing number of people seem to think they’re immune to the sun?

Hartman suggested we call Adewole “Ade” Adamson, a University of Texas at Austin dermatologist and professor prone to disarmingly straight talk in a medical world where people tend to wrap every answer in the cautious vernacular of public health. Adamson said he hadn’t noticed a surge in denialism of the sun’s effects, but such an attitude might be justified among his Black, Asian and Hispanic patients.

“Melanoma is primarily a White person disease,” Adamson told us. “It is not very common in people with darker skin types, period. Period!”

And just like that, our fun little column about sunscreen transmogrified into a bigger mystery with reams of new data to consider.

Of the 39 cancers tracked by the National Cancer Institute, melanoma is the 35th most common among Black Americans. It’s the fifth most common among White folks. Put differently: White Americans have a 3 percent chance of being diagnosed with melanoma in their lifetimes, compared with 0.1 percent for Black Americans, 0.2 percent for Asian Americans and Pacific Islanders, 0.5 percent for Hispanic Americans, and 0.7 percent for Native Americans.

A melanoma forms when cells producing the dark-brown UV-protecting pigment melanin go rogue, sometimes because they were hammered by the very DNA-damaging UV rays they’re designed to block. (You darken or tan in the sun because incoming UV rays signal to your cells that they should probably churn out more melanin.)

To be sure, Americans of non-European descent aren’t immune to melanoma, Adamson said. Their rates are low, not zero. That’s partly because, despite the focus on sun exposure, you can also get non-sun-related melanoma, often in your nails, the palms of your hands or the soles of your feet. (This kind of melanoma, beginning in the toe, felled Robert Nesta Marley in 1981.)

Furthermore, people of color are also more likely to die of melanoma once they’re diagnosed with it. Part of that may have to do with overdiagnosis in White people, Adamson said, but it’s also because people in low-risk groups may not be expecting a melanoma, so they don’t always catch it before it’s too late.

Still, about 95 percent of Americans killed by melanoma from 2008 to 2020 were White, according to the Centers for Disease Control and Prevention. Among 117 causes of death tracked by the CDC, melanoma ranked 91st for Black Americans over that time. That’s below malnutrition, drowning, fire, complications of medical care, hernias, pregnancy and childbirth, and a category called “legal intervention,” which includes police shootings and executions.

Does that mean you can skip the sunscreen if your forebears weren’t White Europeans?

“I don’t have all the answers,” Hartman told us. “But as a scientist, I want to be data-driven. If someone has a really low risk of skin cancer, I don’t really want to hound them to wear sunscreen all day to prevent skin cancer. It doesn’t really make sense. Maybe they should instead take that energy and time and money and focus on eating healthy and exercising.”

Adamson agrees, of course, but the AAD takes a harder line. It clearly advises that all Americans, regardless of skin tone, should wear broad-spectrum SPF 30-plus sunscreen, seek shade and wear protective clothing.

“No one is immune. Melanoma can affect any skin type,” said Desai, who has devoted his career to skin diseases in people of color. “People are dying and we’ve got to work together … to educate the public.”

In some places, melanoma doesn’t look like such a public health crisis. African and Asian nations have some of the lowest melanoma rates in the world, according to the World Health Organization. Northern Europe has some of the highest. And the cancer really runs amok in those places where European colonists have dragged their genes far from the cloudy continent to which they adapted — such as Australia, melanoma capital of the world.

Even on that sunburned continent, top dermatology groups in February endorsed a new sun-safety position statement that says people with the darkest skin colors don’t need sunscreen if they’re going out for less than two hours and the UV index isn’t too high.

The new advice comes in response to concerns about the cost of sunscreen, environmental and otherwise, and about the higher risk of vitamin D deficiencies in people of color, said Rachel Neale, the Queensland professor behind the new effort. Your body needs vitamin D to absorb calcium, move muscles, communicate with the brain and respond to infection. Extra melanin in our epidermis protects us from the sun, but also makes it harder to produce the vitamin.

“If I’m Black … and I’m getting the possible downside of not getting enough vitamin D, that is not a winning public health strategy,” Adamson told us. “That is actually harming. There’s no benefit and clear possible harms.”

(AAD’s Desai counters that “the truth is that there is no level of sun exposure that enables the body to produce ample vitamin D without increasing the risk of skin cancer,” and he questions evidence for the vitamin’s value beyond its crucial role in bone health.)

How do we reconcile the big-picture data with the more dire situation that dermatologists — some of the most elite specialists in the most elite profession in the country — see on the ground?

The answer seems to lie in the fact that these aren’t abstract statistics for the men and women in the trenches. Because of their specialization, dermatologists see a disproportionate share of the small minority of people of color who develop melanoma. And to these patients and their doctors, every melanoma is a tragedy.

“Some people with very dark skin may think they don’t need to protect their skin from the sun because they are not at risk for UV-induced skin cancer,” said Oma Agbai, professor and director of multicultural dermatology at the University of California at Davis Medical Center. “This is a myth, as I’ve seen patients of all skin tones develop skin cancers like squamous cell carcinoma, basal cell carcinoma and melanoma on areas of the skin with high UV exposure.”

She also reminded us, as did many dermatologists, that sun protection isn’t just about avoiding melanoma.

“Everyone can benefit from regular sunscreen application, even those with dark skin and a lower risk of sunburn and skin cancer,” Agbai said, noting that routine sunscreen application can also reduce the risk of other UV-related skin problems, including hyperpigmentation and premature aging.

Hi! The Department of Data craves questions. What are you curious about: Really, why do a growing number of Americans say nothing will happen to them if they spend an hour in the sun? We’ll have more data on this about a year from now; what possible reasons should we test? What parts of the United States are exposed to the most UV? Just ask!

If your question inspires a column, we’ll send you an official Department of Data button and ID card. This week’s envelope goes — via interdepartmental mail — to Stuart.