by Nicola HeathABC Lifestyle
photograph: 123RF / Konstantin Yuganov
A warm spot near a sunny window is an ideal place for them to survive the cold winter months.
But getting sunlight through your windows can affect your health. Here’s what you need to know.
First, what effect does sunlight have on the skin? Damage and Vitamin D
Sunlight is the main source of ultraviolet (UV) radiation. UV radiation, which consists of UVA and UVB rays, can penetrate the skin and cause sunburn, skin cancer, skin aging, and eye damage.
Professor Anne Cust, chair of the Cancer Society’s national skin cancer committee, said ultraviolet light was often confused with infrared light, which we feel as heat from the sun.
“Temperature does not affect UV levels. In fact, cool days can have just as high UV levels as hot days.”
Both long-wavelength UVA and short-wavelength UVB rays can cause sunburn and skin cancer.
UVA rays are the main cause of photoaging, penetrating deep into the dermis and breaking down collagen and elastin, damaging cells.
“UVB has a shorter wavelength than UVA, so it penetrates deeper into the skin,” says dermatologist Leona Yip.
Our bodies also need UVB rays for the synthesis of Vitamin D, which occurs in the epidermis of the skin and is essential for calcium absorption and bone health.
Can you get a sunburn through a window?
Yes, it depends on the type of window glass.
“All types of commercial and auto glass block most of the UVB (vitamin D-producing) radiation, but the amount of UVA radiation that penetrates varies depending on the type of glass,” Professor Kast said.
“Laminated glass used in automobile windshields offers better UV protection than tempered glass, blocking 98% of UVA radiation compared to 79%. Similarly, laminated glass used in buildings blocks UVA radiation completely, while tempered building glass transmits about 70% of UVA.”
“Untinted glass can reduce the penetration of UV rays, but it doesn’t block them completely, which means if you spend a lot of time near an untinted window when UV rays are strong, you could get sunburn. [Index] “Over 3 years old” (this is the usual number in Australia).
The Cancer Society recommends that people who spend long periods of time in a car or near a window take precautions against sunburn, such as wearing long-sleeved shirts, sunglasses, and sunscreen with an SPF of 30 or higher.
Dr. Yip recommends applying sunscreen every morning, even if you spend most of the day indoors.
“If you’re working from home, you’re sitting a few feet away from a glass window or door, and UVA rays can filter through there,” she says.
“Or you go outside to get the mail, walk the dog or hang out the laundry, and that might take 10 to 15 minutes, but for many fair-skinned people, it takes 10 to 15 minutes for them to start burning.”
The Cancer Society recommends that people who spend long periods of time in cars or near windows take precautions against sunburn, such as wearing long-sleeved shirts, sunglasses and sunscreen with an SPF of 30 or higher. (File image)
photograph: Jean Babolak (Unsplash)
Can you get Vitamin D from the sun through a window?
The short answer is no.
Glass blocks 95 percent of UVB rays, so sunlight through a window doesn’t boost vitamin D production.
This is important for your health: Vitamin D is a prohormone, a molecule that your body converts into a hormone needed for calcium absorption.
Vitamin D deficiency can lead to rickets, osteoporosis and osteomalacia, which affects more than one in three Australian adults.
So what’s a safe way to get enough sunlight to meet your vitamin D needs?
Dr Yip says supplements are an option for people with vitamin D deficiency, especially those with very fair skin or a family history of skin cancer. (File image)
photograph: 1234rf
Vitamin D is also found in small amounts in foods such as oily fish and eggs, but the best source is sunlight.
How much time you need to spend in the sun to produce vitamin D depends on several factors, including your skin color, what you’re wearing, where you live, the season, and the UV index.
“Despite UV levels exceeding 3 degrees Celsius almost every day during the summer, most Australians can maintain adequate vitamin D levels by spending a few minutes outdoors most days of the week,” Professor Casto said.
“In parts of southern Australia, during the cooler months, when UV levels are below 3, it is safe to go outside without sunscreen in the early morning or late evening, but once UV levels reach 3 or above we recommend applying sunscreen.”
Dr Yip says supplements are an option for people who are deficient in vitamin D, especially those with very fair skin or a family history of skin cancer.
However, a study published in 2019 found that the majority of healthy adults Australian Medical Journalthey bring little benefit.
– A.B.C.
