One of the most frequently asked questions about sunscreen is whether it must be worn inside. The answer is yes and here’s the science, from physiology to psychology we’ve compiled the ultimate case for indoor SPF. 

Even while working indoors, you may be exposed to UV radiation. This exposure primarily results from unfiltered UV radiation that comes in through windows in buildings and cars. Commercial and residential window glass generally filters out UVB rays, but not UVA rays [1]. Depending on the type of glass and its thickness, anywhere from 0.1% to 72% of UV radiation may be transmitted [1]. Studies have shown that drivers have increased prevalence of photo-damage, actinic keratoses, non-melanoma skin cancers and melanoma on the side exposed to UV radiation from the automobile window [2-6]. Given these findings, we recommend all individuals to apply sunscreen as part of their daily mourning routine.

3 steps to implementing Indoor SPF

#1 Find a sunscreen you love

Finding The Perfect Sunscreen that feels amazing to wear, and doesn’t irritate your eyes and skin makes all the difference. If the experience and results of applying a product are positive rather than a burden, you’re going to keep up with it. Make SPF part of your makeup routine by using it as a primer or BB cream.

#2 Do it everyday

Even if you’re not planning on going outside or even seeing sunlight, research shows that adding a practice to your daily routine daily means a significant decrease in forgetting to perform that habit, thus less risk of getting caught outside without your sunscreen on [7].

#3 Measure your results

Daily sunscreen application has cumulative noticeable effects on the skin. If you’re someone who hasn’t been diligent about sunscreen application and you’re starting your journey, snap some before photos or get your skin tested at a dermatologist. Photos and derm UV cameras can show dark spots and sun damage on the skin. With daily application of sunscreen you may notice a decrease in sun spots, dullness, visible aging, and hyperpigmentation. Visible results make great motivation!

The bottom line

Sun exposure accounts for the majority of skin damage, visible aging and is the biggest risk factor leading to skin cancer. Since the impact of UV light exposure is cumulative on the skin small bouts of daily exposure matter. Wearing at least SPF 30 every day not only protects your skin from small, frequent moments of sun exposure but also provides a lasting habit that will protect your skin years into the future. The bottom line, wear your sunscreen. 

 
[1] Tuchinda C, Srivannaboon S, Lim HW. Photoprotection by window glass, automobile glass, and sunglasses. J Am Acad Dermatol. 2006;54(5):845–854.
 
[2] Foley P, Lanzer D, Marks R. Are solar keratoses more common on the driver’s side? Br Med J (Clin Res Ed). 1986; 293(6538):18
 
[3] Foley PA, Marks R, Dorevitch AP. Lentigo maligna is more common on the driver’s side. Arch Dermatol. 1993;129(9): 1211–1212.
 
 
[4] Singer RS, Hamilton TA, Voorhees JJ, et al. Association of asymmetrical facial photodamage with automobile driving. Arch Dermatol. 1994;130(1):121–123.
 
[5] Butler ST, Fosko SW. Increased prevalence of left-sided skin cancers. J Am Acad Dermatol. 2010;63(6):1006–1010.
 
[6] Department of Health and Human Services FDA, USA. Sunscreen drug products for over the counter human use. Fed Regist. 2019;84:6204–6275.
 
[7] Fritz, H.; Cutchin, M. P. (2016). Integrating the Science of Habit: Opportunities for Occupational Therapy. OTJR: Occupation, Participation and Health, 36(2), 92–98. doi:10.1177/1539449216643307