Is it just me, or is sun-block cream really big business? Until five years ago, SPF 15 was recommended if a person was going to spend more than half an hour in direct sunlight. For a while it was 30 … now we're being told that SPF 45 lotion should be the minimum we use for protection from our sun's UV rays.
The differences in the Sun Protection Factors are often misunderstood. SPF 15 will filter out just a bit more than 93% of all UVB sunlight, whereas an SPF 30 will filter out 97%. So SPF 30 is not "twice as strong" as SPF 15, rather, it will only allow half as much UVB penetration.
Though despite all the warnings we've heard, many of us go without adequate coats of the slippery goop. I've avoided the stuff pretty well over the last decade, only occasionally being forced to apply mixtures of titanium-dioxide and zinc oxide to my skin. But after hearing the recommendation for SPF 45 products for this summer, I started asking myself "has the ozone depleted further?" Oddly enough, no. In fact, the ozone layer has been on the mend for quite some time, albeit slowly. Many sources believe it will be several decades yet before we're naturally protected with pre-1970 levels. Antarctica is the last continent on earth without protection from the sun.
Thinking that the amount of pollution we eject into the atmosphere might offer some protection, I investigated the matter but found no real data to say our greenhouse effect was doing us a favor by obstructing some of these potentially dangerous rays. Perhaps Dr. Roger Angel's title="j2fi.net - Blocking the Sun for $100 Billion a Year">proposed sunshade could act as an artificial buffer ….
2007 is a low point in the Sun's Solar Cycle so the planet will have less chance of being hit by coronal mass ejections, and though the Earth's magnetic field is gearing down to switch polarity for the first time in 780,000 years, it plays little role in UVB protection (but a much bigger role on protecting us from everything else the sun belts out).
So why the SPF 45 minimum?
I've searched through some of the sunscreen manufacturer sites as well as some dermatologist pages, but can't find anything aside from doom and gloom stories about the potential damage to DNA with prolonged exposure to short-wave UVB radiation. While the concerns for genetic damages leading to various forms of cancer is certainly an issue, could this be just another ploy to scare us into buying the (moderately) more expensive product?