Fast Facts on Sunscreen - Get the Coverage You Need

Welcome to June gloom on the Central Coast. Did you know that UV rays are stronger when the weather is cloudy and/or overcast? True story (see below). So it really doesn't matter if you're a sun baby or shade lover, it's essential you have the right coverage.  And when I say the right coverage, I'm referring to a good sun screen with physical block, NOT chemicals.  Trust me, trying to decipher which ingredients are chemicals can be daunting with long unfamiliar names. So here are my quick tips on what to look for when buying sunscreen.

1) On the back of your sunscreen, look at the "active ingredients". If it doesn't say Zinc, Titanium, or a combo of the two - THROW IT OUT! 

2) If the percentage of active ingredients isn't a 12% or higher, it's not doing much to help protect you. 

3) If you don't want to think about it, stop by PASC and pick up any of the sunscreens I have for sale.  They've all been pre-approved by me!  

The article excerpt -

Sounds crazy, and many people just ignore the claim entirely believing it to be a myth. It’s no secret that one can certainly get sunburned on cloudy days, but is there any science backing up the claim that UV rays are actually stronger on cloudy days?


UV intensity can vary widely with time of day, time of the year, and a locations latitude. (The equator at noon receives much more UV exposure than noon in Norway, for example). Clouds do usually block UV rays, particularly the more nefarious UV-B. On a really overcast day, they can stop 70 to 90% of the UV-B from reaching the surface.

Under skies that are only partly cloudy, something interesting happens. A phenomenon called the ‘broken-cloud effect‘ can occur, which causes higher UV levels – higher than a completely clear sky would allow. A survey conducted at six U.S. cites in 1994 found cumulus clouds could raise surface UV-B by 25%, and in 2004 Australian researchers reported that the UV-B rays associated with DNA damage were up to 40% stronger under partly cloudy skies.


Scientists don’t have a solid answer, but there seems to be two main causes. The first is UV rays bouncing off, and being reflected off the sides of dense clouds, and the second is UV rays being redirected as they pass through very fine wisp-like clouds. An American Scientist article suggested last year that a combination of these thin refracting clouds high up and thick reflecting clouds down low could result in a significant UV boost at the surface level.

People are also less likely to take precautions against sun when it’s cloudy which adds to that risk. This leaves them open to any UV-amplifying mechanisms taking place.

Broken-Cloud Enhancement of Solar Radiation Absorption (pdf)
Process for Determining Solar Irradiances (pdf)
Hockberger, P. E. (2002). “A history of ultraviolet photobiology for humans, animals and microorganisms“. Photobiol. 76 (6): 561–579.