Why You Should Be Wearing Sunscreen Daily

May is Skin Cancer Awareness Month and Melanoma Monday! With COVID-19, our usually free skin cancer screening and other outreach programs are canceled. But spreading awareness is still very important.



  • Just 1 blistering sunburn during childhood can nearly DOUBLE a person’s chance of developing melanoma, the deadliest form of skin cancer, later in life.
  • Unfortunately, 20 Americans die from melanoma daily. 
  • Skin cancer is preventable! As a dermatologist and mom, I cannot stress enough the importance of sunscreen, and developing these habits earlier on in life.
  • Wear sunscreen daily. Yes, UV rays will pass through clouds and windows! Make sure to use broadspectrum SPF 30 or higher, and reapply every 2 hours as needed.
  • Seek shade from the hours of 10am-2pm, when UV rays are the strongest.
  • Don’t forget your sun protective clothing and broad-brim hat.. They make life so much easier, so you only need to apply sunscreen to skin that's not covered. 


When patients come to my office looking for anti-aging options, sun protection is always my starting point.  Aside from skin cancer risks, over 90% of the aging we see on our skin is from the sun (link).  Most sun damage (dermatoheliosis) occurs in our teens and 20’s, which is often a time in our lives we prize glowing tanned skin.


However, dark skin is unfortunately a signal that our skin is trying to protect itself from further sun damage and burns.  The results are not immediate, but I am frequently asked by patients in their 30s and 40s who are astonished by the fact that their “dry skin” is a result of sun exposure from just a decade prior.


The other comment I often hear in Minnesota is: “I’m rarely in the sun”.  Most folks define sun exposure only as being in direct sunlight outdoors, but don’t realize that cloudy days, winter days, and being in our car are all times that we are exposed to UV light.  The average American is exposed to UV light for 101 minutes per day while driving (Harvard Health Watch).  As discussed in my previous post, the UVA light that penetrates windows and clothing is also the spectrum responsible for photo-aging.  

Although we have cosmetic procedures and proclaimed miracle creams that may help with wrinkles or sun spots, nothing can truly reverse the signs of aging. Many of my patients wished that they could tell their younger selves to have added some sunscreen to their daily routines.


Now that you’ve committed to adding sunscreens to your morning regiment, let’s talk more about your options. Sunscreens are divided into 2 varieties: chemical and physical blockers. Chemical sunscreens work by absorbing the UV light and contain active ingredients such as homosalate, octinoxate, oxybenzone, and avobenzone. These chemicals work by breaking down after being in contact with UV light, which is why sunscreen bottles always tell us to re-apply.


Physical blockers on the other hand, are made up of zinc oxide and/or titanium dioxide. They act like a mirror and physically reflect light off of skin without breaking down, therefore have slightly broader UV coverage, and require less frequent reapplication. It is also better suited for sensitive skin individuals. The downside, however, is the consistency of the physical blockers comes as a white chalky paste that’s difficult to spread evenly and contributes to the vampire look. Fortunately, many companies have been able to refine physical sunscreens to micronized particles, giving a much silkier and translucent application.


 Sunscreen’s efficacy against UV radiation, specifically UVB, is measured by SPF, which is followed by a number.  It is determined by the ratio of sunscreen protected skin over unprotected skin. For example, SPF 15 means if it takes 10 minutes for your unprotected skin to start turning red in the sun, using an SPF 15 sunscreen theoretically prevents reddening 15 times longer. Additionally, SPF 15 blocks about 94% of UVB and SPF 30 blocks greater than 97%, which is why you will find most dermatologist recommend using sunscreen of at least SPF 30.


In European and Asian countries, UVA blockage on sunscreens are labeled PA (protection again) + to +++. However, this measurement is not utilized in the US, as we currently do not have a standardized UVA protection measurement available. Therefore, most dermatologist recommend sunscreens labeled “broad spectrum” to ensure both UVA and UVB coverage.


Most people are not applying enough sunscreen to get the adequate SPF coverage. At least one ounce (shot glass) amount is needed for the entire body, including 1 teaspoon applied to the head and neck area. You should never rely on the sunscreen in your foundation or BB cream. If you’re active, swimming, or sweating, then reapplication is needed every 2 hours; also look for sunscreens with designated water resistant on the label for more long-lasting coverage.



Dr. Jenny Liu is a board-certified dermatologist and an assistant professor in the Twin Cities. Her academic interests are complex medical dermatology, ethnic dermatology and medical education. Her platform and blog are intended for education and to share her passion for medicine, skin care, fashion, and motherhood. For more information, be sure to follow her @derm.talk, or email at: dermtalkdocs@gmail.com



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