A doctor has shared why she consistently applies suntan lotion indoors, even during her commute and while at her desk. With a fourth heatwave underway across much of the UK, temperatures are expected to reach up to 35°C today (July 29), especially in the Midlands and southern and eastern England.
Extended periods of sunshine increase the risk of sunburn and skin cancer, making sun cream essential when outdoors. However, experts note that protection matters indoors as well.
UVA Exposure Through Windows
Trisha Pasricha, MD, an instructor in medicine at Harvard Medical School, addressed the topic in a recent column. She explained that wearing sunscreen indoors is necessary despite seeming "counterintuitive."
Pasricha wrote for The Washington Post: "Why do people in the United States tend to get more skin cancers on their left side, while people in Australia appear to get more sun damage on the right? The answer is UVA exposure while driving."
She noted that standard glass in windows blocks UVB rays, which cause sunburn, but offers little protection from UVA or visible light. Both can accelerate skin ageing, according to Pasricha, citing a 2011 study of over 82,000 melanoma cases and about 2,400 Merkel cell carcinoma cases. The study found both cancers were slightly more frequent on the left side, mirroring studies in Australia where drivers sit on the right, showing pre-cancerous patches more often on the right.
Daily Sunscreen Use
Pasricha added: "So, yes, I do wear sunscreen every day despite working indoors. I commute at least 45 minutes to my office each way. I also face a nice, large window behind my computer screen when I'm there." She explained that even without stepping outside, her skin receives UVA rays for much of the day.
NHS Sun Safety Advice
The NHS warns that sunburn increases the risk of skin cancer and notes that sunburn can occur in the UK even on cloudy days. It states there is "no safe or healthy way" to get a tan and recommends staying in shade during peak sunlight. If the UV index is 3 or higher, protection is advised.
The health service advises using at least factor 30 sunscreen, applying enough, and reapplying often. Additional measures include covering skin with clothing, wearing sunglasses, and taking extra care with children and babies. Babies under 6 months should be kept out of direct sunlight.
