It's called air conditioning.
Edited to Add:
I had an interesting exchange with Dr. Cicero Coimbra, MD, PhD, on his high dose vitamin D3 protocol for his MS patients. The starting vitamin D3 dose is 1000 IU vitamin D3 per Kg body weight per day. At 80 Kg, I would be taking 80,000 IU/day vitamin D3 if I was on his treatment protocol.
When I asked why so many people had MS in Sao Paulo, Brazil where the Latitude is -23.5º North, about the same distance South of the equator as Key West, FL is North of the equator, so they should be getting lots of cutaneous vitamin D3 from the sun, he replied "They all have the same problem."
When I asked what problem was that? He replied, "Air conditioning."