The sun, our skin and our sunscreen

Protecting yourself when you venture outdoors

Posted 7/3/24

The outdoor life has blossomed in our region, inviting us to embrace nature’s splendor. Usually, I grab whatever sunscreen is left over from previous years and run outside. I know I need to …

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The sun, our skin and our sunscreen

Protecting yourself when you venture outdoors


The outdoor life has blossomed in our region, inviting us to embrace nature’s splendor. Usually, I grab whatever sunscreen is left over from previous years and run outside. I know I need to apply at least an SPF of 30 and reapply regularly. That, dear reader, is where I was when I started my research for this article.

The warm weather and long days hold many challenges for skin, from prolonged exposure to sunlight to unpredictable shifts in weather conditions. Protecting our skin is not merely about preserving its outward appearance but also about safeguarding its health and reducing the risk of long-term damage and potential skin cancer.

The benefits of sunlight

Sunlight offers numerous benefits, including the synthesis of vitamin D, an essential nutrient involved in many of our body’s systems. It also possesses antibacterial properties and has been shown to enhance mood and improve sleep quality. 

The optimal duration of sun exposure varies based on skin type, with approximately 10-15 minutes recommended for lighter skin tones and 25-40 minutes for darker skin tones to reap these benefits. However, it’s crucial to remember that even during this beneficial sun exposure, sunscreen is still necessary to protect your skin from harmful UV radiation.

 Sunscreen: Organic compounds vs. inorganic

One of the first lines of defense against harmful UV radiation is sunscreen. Sunscreens come in two main types: organic (chemical) and inorganic (physical or mineral) filters. Organic sunscreens contain carbon-based compounds that absorb UV radiation and convert it into heat, while inorganic sunscreens contain minerals like zinc oxide or titanium dioxide that form a physical barrier on the skin, reflecting and scattering UV rays.

 UV radiation types and effects

UV radiation consists of three main types: UVA, UVB and UVC. Each type differs in wavelength, penetration depth, and effects on the skin.

  1. UVA radiation:

Wavelength: UVA radiation has the longest wavelength (320-400 nanometers) among UV radiation types.

Penetration depth: UVA rays penetrate the skin more deeply than UVB rays, reaching the dermis, the skin’s middle layer.

Effects on skin: UVA radiation contributes to premature skin aging by causing wrinkles, fine lines and loss of elasticity. It also plays a significant role in the development of skin cancer, particularly melanoma.

  1. UVB radiation:

Wavelength: UVB radiation has a medium wavelength (290-320 nanometers) compared to UVA and UVC.

Penetration depth: UVB rays primarily affect the skin’s outer layer, the epidermis.

Effects on skin: UVB radiation is the primary cause of sunburn and directly damages DNA in skin cells, increasing the risk of skin cancer, including basal cell carcinoma and squamous cell carcinoma.

  1. UVC radiation:

UVC radiation has the shortest wavelength (100-290 nanometers) and is mostly absorbed by the Earth’s atmosphere, so it does not reach the skin’s surface in significant amounts.

Nanoparticles in sunscreen

Nanoparticles, particularly those used in mineral sunscreens like zinc oxide and titanium dioxide, have raised concerns regarding their potential to penetrate the skin barrier and enter the bloodstream. Nano-sized mineral particles are used because they offer advantages such as improved cosmetic elegance and a reduced whitening effect on the skin. But their small size raises questions about their safety and long-term effects. 

Recent research indicates that nanoparticles in sunscreen formulations, particularly those containing zinc oxide and titanium dioxide, may indeed penetrate the outermost layers of the skin, but their ability to reach the bloodstream and have systemic effects remains a topic of debate and ongoing study.

Factors such as particle size, surface coating, sunscreen formulation, and method of application (e.g., spray vs. cream) can influence the skin penetration of nanoparticles. For instance, nanoparticles in spray sunscreen may be more likely to be inhaled and enter the respiratory system, raising concerns about potential lung toxicity, whereas creams or lotions can have lower inhalation risks but could still lead to skin absorption. Overall, while nanoparticles in sunscreen formulations have the potential to penetrate the skin’s outer layers, current evidence suggests that their systemic absorption and distribution throughout the body are limited.

Why application matters

The method of sunscreen application can also influence its effectiveness and safety, especially concerning nanoparticle-containing formulations. Spray sunscreens, for example, can pose inhalation risks, as nanoparticles can become            airborne during application and can potentially be inhaled into the lungs. Additionally, spray sunscreens might provide uneven coverage and require careful application to ensure adequate protection.

In contrast, cream or lotion-based sunscreens allow for more controlled and uniform application, minimizing the risk of missed spots or insufficient coverage. Cream formulations also provide the opportunity for thorough spreading and massaging into the skin, ensuring better adherence and efficacy, particularly for mineral sunscreens containing nanoparticles.

Sunscreen and small business

For small-scale producers of sunscreen, ensuring consistent SPF function in each batch can be a significant challenge. Lab testing for SPF efficacy requires specialized equipment and expertise, which can be costly and impractical for small businesses with limited resources. As a result, some small producers can face difficulties in conducting regular batch testing to verify the SPF levels of their products. 

Furthermore, regulatory requirements for sunscreen testing and labeling add another layer of complexity for small producers, as compliance with stringent standards is necessary to ensure product safety and efficacy. Because this is an issue of relatively high risk, it’s a serious question whether small producers can adequately protect their consumers.

Natural alternatives to sunscreen

Recent claims that plant oils confer SPF are complicated. They might be helpful depending on the selection of fixed oil during the formulation of sunscreens. But if used alone, the oils offer minimal benefit and the risk of cancer far outweighs the potential benefit.

Sunscreen cost

Why do some sunscreens cost more than others? The answer lies in the added ingredients that high-end brands include in their formulations. These could include hyaluronic acid, peptides or antioxidants. They do not protect the skin better, but might feel lighter on your skin.

Organic sunscreen

A certified organic sunscreen is petrochemical-free and typically uses zinc oxide as the active ingredient.

Last words on being sun smart

When it comes to overexposure to UV radiation, the Australian Council says there are five S’s to keep in mind: “slip, slop, slap, seek and slide.” This means:

- Slipping on sun-protective clothing

- Slopping on sunscreen

- Slapping on a broad-brimmed hat

- Seeking shade when and where possible

- Sliding on sunglasses

In addition to sunscreen,  consider garments made from fabrics specifically designed for sun protection and moisture management.

UPF (Ultraviolet Protection Factor) clothing and arm sleeves: UPF clothing is specially treated or woven with materials that block UV radiation, providing enhanced sun protection for exposed skin. Brands such as Coolibar, Columbia and REI offer a wide range of UPF-rated clothing, including shirts, pants, hats and arm sleeves, designed specifically for outdoor activities like gardening and hiking.

By following these guidelines, you’ll be well on your way to enjoying the great outdoors without turning into a human raisin. Happy adventuring!

Hedy Schneller is the founder of Illumia, a local skincare company that focuses on quality, transparency and natural self-care. The products, crafted with local, fresh, and healthy ingredients, embody a commitment to therapeutic skincare with a minimal carbon footprint. Learn more at

sunlight, sunscreen, SPF, summer, UV, radiation


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