Skip to main content

Is SPF 60 twice as good as SPF 30? What is SPF anyway?

 


SPF stands for Sun Protection Factor, and it measures the level of protection that a sunscreen offers against the sun's harmful ultraviolet (UV) rays. The higher the SPF number, the more protection the sunscreen provides.... kind of....

It is important to note that SPF is a logarithmic scale, which means that the level of protection does not increase linearly with the SPF number. Since this is not a math lesson, lets look at a few examples instead. For example, an SPF 15 sunscreen filters out about 93% of UVB rays, while an SPF 30 sunscreen filters out about 97% of UVB rays. Or said another way, Going from SPF 15 to SPF 30 increases the protection by only 4%.

Here are some examples of the level of protection provided by different SPF numbers:

  • SPF 15: This sunscreen filters out about 93% of UVB rays. It is a good option for everyday use and is suitable for people who spend limited time in the sun.

  • SPF 30: This sunscreen filters out about 97% of UVB rays. It is a good choice for people who spend more time in the sun, such as those who work outdoors or participate in outdoor activities.

  • SPF 60: This sunscreen filters out about 98% of UVB rays, while SPF 90 filters out about 98.9% of UVB rays. They sound impressive... but practically speaking they are about the same as SPF 30.

It is important to remember that no sunscreen provides 100% protection against the sun's rays, and it is still possible to get sunburned even when wearing sunscreen. To achieve the listed SPF values, it is also critical to use the sunscreen correctly. Typically 1oz (or a shot glass full) of sunscreen is needed for a full body. Most sunscreen is sold in 4oz bottles, and it is recommended to re-apply sunscreen every 2 hours. A typical family of 4 at the beach should anticipate going through a few bottles of sunscreen on their trip. In reality - a single bottle will likely last that family multiple outings. This is one of many reasons why protective clothing, such as hats, sunglasses and long-sleeved shirts, and avoiding too much time in the sun, especially during peak hours (10am-4pm) may be even more important than the SPF # on your bottle.

Labels:

Comments

Post a Comment

Popular posts from this blog

Dermatologist's Insight: The Significance of Waterproof Bandages in Infection Prevention

As dermatologists, we understand the importance of protecting wounds from infection. Even seemingly minor cuts, scrapes, or surgical incisions can become a gateway for harmful bacteria when exposed to moisture during activities like showering. In this article, we will highlight the crucial role of waterproof bandages in reducing the risk of infection. By keeping wounds covered with a waterproof barrier, we can significantly safeguard against potentially harmful pathogens. Understanding the Showering Process and Infection Risk: Showering is an essential part of our daily hygiene routine, but it can introduce a variety of germs and bacteria to our skin. When water flows over our body, it carries bacteria, fungi, and other microorganisms that naturally reside on the skin's surface. If there is an open wound, these microorganisms can enter and cause an infection. The Role of Waterproof Bandages in Infection Prevention: Waterproof bandages act as an effective barrier, preventing water...
Post a Comment
Read more

Dermatologist's Guide: Seat Cushions for Pressure Ulcer Prevention on the Buttocks

  As a dermatologist, I often encounter patients who suffer from pressure ulcers, particularly on the buttocks. Pressure ulcers, also known as bedsores, can be debilitating and challenging to treat. They primarily affect individuals who are bedridden or spend prolonged periods seated, such as the elderly. In this article, we will discuss the importance of seat cushions, specifically donut cushions, in protecting the skin and preventing pressure ulcers, especially among the elderly who may have reduced protective fat and lead sedentary lifestyles. Understanding Pressure Ulcers on the Buttocks: Pressure ulcers develop due to prolonged pressure and inadequate blood flow to specific areas of the body. The buttocks are particularly vulnerable to these sores as they bear much of our body weight during sitting or lying down. Factors contributing to pressure ulcer development include prolonged immobility, reduced protective fat padding, poor nutrition, and friction or shear forces against ...
Post a Comment
Read more

A Clever Trick - Try Frozen Milk Cubes For Bug Bites.

As a dermatologist, I often have patients who come in complaining of itchy bug bites. While scratching may provide temporary relief, it can actually cause more harm than good, leading to skin irritation, infection, and scarring. That's why I'm always on the lookout for safe and effective alternatives to scratching. Here is a trick that I often recommend to my patients: freezing whole milk into ice cubes ( here is a perfect tray for it ) and using them to soothe bug bites or itchy areas of the skin. While it may sound unconventional, there is actually some scientific evidence to support the use of milk as a natural anti-inflammatory agent. Milk contains contains proteins and fats that can help to soothe irritated skin and reduce inflammation. When milk is frozen into ice cubes, it provides a cooling sensation that can further help to relieve itching and discomfort. To use milk ice cubes for bug bites or itchy skin, simply freeze whole milk in an ice cube tray and apply the cubes...
Post a Comment
Read more