Yes, you do need to wear sunscreen indoors – here’s why

We might still be spending a lot of time inside, but that doesn’t mean you should forgo that daily dose of SPF

UVA rays can penetrate windows and clouds, meaning you're not necessarily protected against sun damage when indoors. Unsplash

It is, hopefully for most of us, a daily ritual.

Whether found in your moisturiser, foundation or a separate SPF, slapping on a healthy dollop of sun protection is a must when heading outdoors.

But it’s not only outside where your skin is at risk.

Contrary to popular belief, you’re still susceptible to the sun’s rays, even when indoors.

So, if you’ve been forgoing that necessary skincare step while staying home amid the ongoing pandemic, now’s the time to reintroduce it to your daily routine.

“Glass windows from our houses and cars can filter most of the UVB rays, which is the main ray responsible for the generation of skin cancer,” says Dr Rutsnei Schmitz, a specialist dermatologist at Dubai's Medcare Women and Children Hospital. “But windows will not protect you from other radiation such as UVA and visible light radiation.”

Both UVB and UVA, the two most common ultraviolet rays present in sunlight, can have negative effects on the skin.

UVB has a shorter wavelength, and is predominately responsible for causing sunburn. UVA, however, has a longer wavelength and is associated with causing skin ageing, though both can be responsible for causing more serious conditions.

“UVA rays can also play a role in the development of skin cancer, and lead to ageing of the skin, wrinkles and age spots,” explains Schmitz. “Visible light is related to pigmentation issues like melasma.”

Look for SPFs of at least 30, advises dermatologist Dr Rutsnei Schmitz

UVA rays are actually far more prevalent, accounting for up to 95 per cent of the UV radiation that reaches the Earth, says the Skin Cancer Foundation.

“These rays maintain the same level of strength during daylight hours throughout the year,” the organisation states, unlike UVB, the intensity of which fluctuates throughout the day and seasons.

UVA also penetrates the skin more deeply than UVB – as well as penetrates through clouds – and is the type of ray used in typical suntan beds.

So it doesn’t matter whether you’re behind the supposed protection of your windowpane – you could still be prematurely ageing and damaging your skin by not taking proper precautions, inside or outside.

You do have to reapply as after three hours, even indoors, sweat washes off around 50 per cent of sunscreen

Both UVA and UVB rays negatively impact unprotected skin, meaning you need a broad-spectrum sun cream to combat the two.

(Yes, even though you’re probably only vulnerable to the former indoors, you might as well invest in a good-quality SPF that you can use any day.)

“You should look for a sunscreen that has at least an SPF30 (that indicates the protection level for UVB), and UVA+++,” advises Schmitz, which can be used both indoors and out.

Any parts of your skin exposed to sunlight, whether directly or through windows, should be protected. Skin covered by clothing does not need a pre-application of SPF, however.

And a once-a-day application doesn’t quite cut the mustard, even when inside your home.

“You do have to reapply as after three hours, even indoors, sweat washes off around 50 per cent of sunscreen in that time, even in cooled environments,” explains Schmitz.

Reapply sunscreen every three hours

When it comes to finding the right sunscreen, most bottles you’ll find on supermarket and pharmacy shelves fall into two categories: mineral and chemical. Both are effective, but mineral – which will contain either titanium dioxide, zinc oxide or both – will typically be a thicker cream that could leave a telltale white cast on the skin.

Chemical, meanwhile – made from a longer list of ray-deflecting ingredients, such as oxybenzone or avobenzone – is more common in water-resistant creams, but can occasionally irritate extra-sensitive skin.

“Mineral sunscreens are indicated for people with sensitive skin and for sport practice,” says Schmitz. “Their big disadvantage is that they are less cosmetically pleasing, as they are thicker and whiter. Chemical sunscreens offer effective protection, but can be formulated in light, non-sticky lotion. They are indicated for regular use.”

Some formulations also blend ingredients from both camps.

To check you are not allergic to any sunscreen, Schmitz recommends conducting a patch test before using formulas on sensitive areas.