Sunscreen for Dummies

Written by: Tushar Sharma

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When it comes to selecting sunscreen, the options might seem overwhelming. With an array of brands and SPF numbers on the shelves, it's essential to understand what these numbers mean and the importance of using sunscreen. Let's delve into the science behind it.

What is Sunscreen and Why Do We Need It?

Sunscreen is a product designed to protect our skin from the sun's harmful ultraviolet (UV) rays. These UV rays are a type of electromagnetic radiation emitted by the sun. While the visible light that we perceive with our eyes ranges from approximately 400 to 700 nanometers (nm) in wavelength, the sun also emits UV rays which fall outside of this visible spectrum.

Specifically, UV rays are categorized into two primary types based on their wavelengths:

UVA rays: These have wavelengths ranging from 315 to 400 nm. They are known for causing premature skin aging and potentially contributing to skin cancer.
UVB rays: These have wavelengths ranging from 280 to 315 nm. They are primarily responsible for sunburn and play a key role in the development of skin cancer.

Fun Fact: Bees can see ultraviolet light, a capability that humans lack. This ability helps them locate flowers and navigate.

Sunscreen works by incorporating active ingredients that either absorb, reflect, or scatter harmful UV rays, preventing them from penetrating the skin.

Understanding SPF

The term "SPF" stands for "Sun Protection Factor." Contrary to common misconceptions, the SPF number does not represent the percentage of UV protection. Instead, it indicates how much longer you can stay in the sun without getting sunburned compared to not wearing any sunscreen. For example, an SPF 15 sunscreen theoretically allows you to stay in the sun 15 times longer without getting burned.

However, the protection is not linear:

SPF 15 filters out about 93% of UVB rays
SPF 30 filters out about 97% of UVB rays
SPF 50 filters out about 98% of UVB rays

No sunscreen can block 100% of UV rays. While higher SPF sunscreens provide slightly better protection, the increase becomes marginal after a certain point.

Is There a Concern with Using Too Much Sunscreen?

While sunscreen is vital for protecting against UV damage, some concerns have been raised about excessive use:

Vitamin D Deficiency: Sunlight helps our skin produce vitamin D. Over-reliance on sunscreen can potentially reduce vitamin D production, leading to deficiencies. However, it's important to strike a balance – short periods of sun exposure without sunscreen can aid in vitamin D synthesis.
Chemical Exposure: Some sunscreens contain chemicals that may have potential health concerns. For instance, ingredients like oxybenzone and octinoxate, while effective UV filters, have raised concerns due to their potential endocrine-disrupting properties.
Skin Cancer Concerns: There's no direct evidence suggesting that sunscreen use promotes skin cancer. However, relying solely on sunscreen and neglecting other protective measures, like wearing hats and protective clothing, can give a false sense of security and potentially increase sun exposure, raising skin cancer risk.

Reef-Safe Sunscreens

With the increasing awareness of environmental concerns, many sunscreens now tout being "reef-safe." These sunscreens are formulated without oxybenzone and octinoxate, two common sunscreen ingredients that have been found to be harmful to coral reefs. If you're planning a trip to an area with coral reefs or want to make an eco-conscious choice, it's advisable to opt for a reef-safe sunscreen.

Several tourist destinations around the world, particularly those with sensitive marine ecosystems, have started regulating the use of sunscreens. Some places have even gone to the extent of banning sunscreens that aren't labeled as "reef-safe". These regulations are in response to scientific findings that certain chemicals found in many sunscreens, like oxybenzone and octinoxate, can cause coral bleaching and are harmful to marine life.

Hawaii: In 2018, Hawaii became the first US state to pass a bill banning the sale of sunscreens containing the chemicals oxybenzone and octinoxate, effective from January 1, 2021.
Palau: The Pacific island nation of Palau took a similar approach, banning sunscreens with any of the ten key ingredients believed to harm marine life. This regulation took effect in 2020.
Key West, Florida: Following suit, Key West in Florida also voted to ban the sale of sunscreens containing oxybenzone and octinoxate from January 2021.
Mexican Caribbean: Some parts of the Mexican Caribbean, including protected marine areas around Cancun, Cozumel, and Playa del Carmen, have regulations urging tourists to use only biodegradable or reef-safe sunscreens.

Many of these destinations either outright ban non-reef-safe sunscreens or strongly encourage tourists to opt for biodegradable alternatives. Some dive shops, hotels, and tour operators even provide reef-safe sunscreen samples or sell them as part of their commitment to marine conservation.

Conclusion

When selecting a sunscreen, choose one that offers broad-spectrum protection (against both UVA and UVB rays), is water-resistant if you're engaging in water activities, and has an appropriate SPF for your skin type and activity level. Always remember to apply generously and reapply regularly, especially after swimming or sweating.