Decoding Sunscreen: From the Drug Store to the Beach

With the arrival of the summer season, it's time to soak up the sun and enjoy the outdoors. However, it's essential to prioritize your skin's health and protect it from the harmful effects of the sun's rays. Sunscreen plays a crucial role in safeguarding your skin, but with numerous options available, it can be overwhelming to choose the right one. In this blog post, we'll delve into the world of sun care and explore the difference between chemical and physical sunscreens, discuss what SPF vs. PA ratings mean, and mention application tips, empowering you to make informed choices for optimal skin protection.

Chemical Sunscreens

Sunscreens are topical products designed to shield the skin from harmful ultraviolet (UV) radiation. They work by either absorbing or reflecting UV rays, preventing them from penetrating the skin's deeper layers. Sunscreens come in two primary formulations: chemical and physical. Chemical sunscreens contain organic compounds that create a chemical reaction when exposed to UV rays. These compounds, such as oxybenzone, avobenzone, or octinoxate, absorb the UV radiation and convert it into heat, which is then released from the skin.

Key Features of Chemical Sunscreens:
• Lightweight and often easier to apply evenly
• Can offer broad-spectrum protection against UVA and UVB rays
• May require around 15 minutes to activate after application

Pros of Chemical Sunscreens:
• Offer higher SPF (Sun Protection Factor) values, typically ranging from 15 to 100+.
• Generally more resistant to sweating and water
• Less likely to leave a white cast on the skin
• Formulas tend to be less sticky and overall more cosmetically appealing

Cons of Chemical Sunscreens:
• Some individuals may experience skin sensitivity or allergic reactions to specific chemical ingredients
• Chemical filters may break down when exposed to the sun, necessitating frequent reapplication
• Potential environmental concerns associated with certain chemical ingredients (e.g., oxybenzone) and their impact on coral reefs

Pro Tip:
• Sunscreens that combine chemical AND mineral protection offer broader spectrum coverage from both UVA and UVB radiation. UVA = responsible for skin AGING. UVB = responsible for skin BURNING.

Physical Sunscreens

Physical sunscreens, often referred to as mineral or inorganic sunscreens, contain active mineral ingredients, such as titanium dioxide or zinc oxide. These minerals act as physical barriers, reflecting and scattering both UVA and UVB rays away from the skin's surface.

Key Features of Physical Sunscreens:
• Formulated with naturally-occurring minerals
• Provide immediate protection upon application
• Less likely to cause skin irritation or allergies

Pros of Physical Sunscreens:
• Ideal for individuals with sensitive skin or prone to skin conditions like rosacea or eczema
• Offer excellent broad-spectrum protection against UVA and UVB rays
• Provide immediate protection without the need for pre-application wait times
• Longer shelf life compared to chemical sunscreens

Cons of Physical Sunscreens:
• Can be thicker and leave a white cast on the skin, although newer formulations aim to minimize this effect
• May require more frequent reapplication, especially after sweating or swimming
• Typically offer lower SPF values (between 15 and 50), but still provide effective protection

Pro Tip:
• Nano (vs. non-nano) zinc oxide formulas are usually pastier, but offer great broad-spectrum coverage without being biologically active. This is a great option to use on kids because you can see exactly where the sunscreen has and hasn’t been applied.

Understanding SPF (Sun Protection Factor)

When shopping for sunscreen, you'll often come across the term "SPF," which stands for Sun Protection Factor. SPF is a measure of a sunscreen's effectiveness in protecting the skin from UVB (ultraviolet B) rays, which are responsible for sunburns and contribute to skin cancer. 

Here's what you need to know about SPF:
• Degree of Protection: The SPF number indicates the degree of protection a sunscreen offers against UVB rays. The higher the SPF, the greater the protection. For example, an SPF 30 sunscreen filters out approximately 97% of UVB rays, while an SPF 50 sunscreen filters out about 98%.

• The Calculation: SPF is calculated by comparing the amount of time it takes for skin to burn with and without sunscreen. For instance, if your skin would typically burn in 10 minutes of sun exposure, an SPF 30 sunscreen would theoretically allow you to stay in the sun for 300 minutes (10 minutes multiplied by the SPF factor of 30) before burning.

• Type of Protection: SPF primarily measures the effectiveness of a sunscreen against UVB rays, as before mentioned. However, it does not provide information about protection against UVA rays, which are associated with skin aging and deeper skin damage.

• Factors to Consider: It's important to note that SPF is not a linear scale. The increase in protection between SPF 30 and SPF 50 is relatively small (1%). No sunscreen can provide 100% protection, and it's recommended to combine sunscreen with other sun protection measures like seeking shade and wearing protective clothing.

• Reapplication: Regardless of the SPF level, it's crucial to reapply sunscreen every two hours, or more frequently if you're sweating, swimming, or towel-drying. Reapplication helps maintain the effectiveness of the sunscreen throughout the day.

Understanding PA Ratings

When choosing a sunscreen, you may come across PA ratings. The PA rating system originated in Japan and has become widely adopted across Asian countries. PA stands for "Protection grade of UVA" and indicates the level of protection against UVA rays, which are known to cause skin aging and contribute to skin cancer. The PA rating is represented by a "+" symbol followed by a number of pluses (+++). The more plus signs, the higher the level of UVA protection.

Here's a breakdown of the PA rating system:
• PA+ indicates some UVA protection
• PA++ offers moderate UVA protection
• PA+++ provides high UVA protection
• PA++++ signifies extremely high UVA protection

While the PA rating system focuses on UVA protection, it's important to note that sunscreens with higher SPF values also offer substantial UVA and UVB protection. Therefore, it's advisable to select a broad-spectrum sunscreen with both a high SPF and a high PA rating to ensure comprehensive protection against the sun's harmful rays. Remember that the PA rating system is not commonly used outside of Asian markets, and many sunscreens sold in other regions may not display a PA rating. However, they still undergo rigorous testing to ensure their effectiveness against UVA and UVB radiation.

The Anti-Aging Benefits of Sunscreen

Prolonged and unprotected exposure to the sun's UV radiation can accelerate the aging process of the skin. This is known as photoaging, which manifests as wrinkles, fine lines, age spots, and a loss of skin elasticity. Sunscreen acts as a protective barrier, shielding your skin from harmful UVA and UVB rays that contribute to premature aging. When it comes to skincare and maintaining a youthful appearance, sunscreen plays a crucial role.

Here's how sunscreen acts as an anti-aging ally for your skin:
• Reduces Wrinkles and Fine Lines: Sun damage can lead to the breakdown of collagen and elastin fibers in the skin, resulting in the formation of wrinkles and fine lines. By wearing sunscreen daily, you can help preserve the structural integrity of your skin and minimize the appearance of these signs of aging.

• Maintains Skin Elasticity: UV radiation damages the elastic fibers in the skin, leading to a loss of skin elasticity and sagging. By using sunscreen consistently, you can help preserve the elasticity of your skin, keeping it firm and supple.

• Prevents Hyperpigmentation: Uneven skin tone, dark spots, and hyperpigmentation are common signs of sun damage. UV radiation stimulates the production of melanin, the pigment responsible for skin color. Sunscreen helps to inhibit this process, reducing the risk of developing dark spots and maintaining a more even complexion.

• Minimizes the Risk of Skin Cancer: Somewhat of an anti-aging benefit, sunscreen is vital for protecting against skin cancer. Prolonged and unprotected sun exposure is a significant risk factor for developing various types of skin cancer. Regular use of sunscreen reduces this risk and ensures long-term skin health.

Pro Tip:
• It's important to note that the anti-aging benefits of sunscreen are not limited to sunny days or summer months. UV rays can penetrate clouds and windows, making it essential to incorporate sunscreen into your daily skincare routine year-round.

Applying the Information (& the Sunscreen)

Proper sun care is crucial for maintaining healthy skin and protecting against the damaging effects of UV radiation. Whether you opt for chemical or physical sunscreens, remember to choose a broad-spectrum formula with a suitable SPF, apply it generously, and reapply regularly. Additionally, complement your sun protection routine with protective clothing, seeking shade, and staying hydrated. By prioritizing sun safety, you can enjoy outdoor activities while safeguarding your skin's health for years to come.

General Tips for Proper Sun Care:
• Choose SPF Wisely: Opt for a sunscreen with a broad-spectrum SPF of 30 or higher (50+ for bonus points) to protect against both UVA and UVB rays effectively.

• Apply Generously: Use a sufficient amount of sunscreen to cover all exposed areas of your body. For the face, a teaspoon-sized amount is recommended.

• Reapply Regularly: Regardless of the type of sunscreen you choose, reapplication is essential every two hours, or more frequently if you're swimming, sweating, or towel-drying.

Other Ways to Protect Your Skin from the Sun:
• Wear Protective Clothing: Alongside sunscreen, wearing clothing that covers your skin can provide an additional layer of protection. Opt for lightweight, tightly woven fabrics, long-sleeved shirts, wide-brimmed hats, and UV-blocking sunglasses.

• Seek Shade: Limit your time in direct sunlight, especially during peak hours when the sun's rays are the strongest. Find shade under trees, umbrellas, or canopies to reduce your exposure to UV radiation.

• Be Mindful of Reflective Surfaces: Remember that surfaces like water, sand, snow, and concrete can reflect and intensify UV radiation. Take extra precautions in these environments by increasing your sun protection measures.

• Stay Hydrated: Spending time under the sun can lead to dehydration. Drink plenty of water throughout the day to keep your skin and body hydrated.

• Practice Sun Safety for Children: Children have sensitive skin and are more vulnerable to the sun's harmful effects. Keep infants under six months old out of direct sunlight, dress them in protective clothing, and apply mineral sunscreen to exposed areas. For older children, encourage sun-protective habits and make sure you walk the talk.

Last Pro Tip:
• For effective application, cover two fingers (index & middle finger) each with a line of sunscreen. These lines should extend from the joint where the finger meets the palm, all the way to the tip of that finger. This is about the correct amount you’ll want to apply to your face and neck. I find this useful since I apply sunscreen to these sun-exposed areas almost every day.

Happy sunning!

Author: Emily Howard, ND, BSc

© Copyright 2025 Dr. Emily Howard. All Rights Reserved.