Sometimes I hear people explain firewall effectiveness in terms of SPF ratings on sunscreen. I like the concept but it also tempts me to pull out the annual Environmental Working Group (EWG) suncreen hall-of-shame. The EWG offers nuggets of wisdom such as this:
Sky-high SPF products may protect from sunburn, caused primarily by UVB rays, but they leave children vulnerable to skin-damaging UVA rays. Without the warning signal of sunburn, children stay in the sun too long, and UVA damage builds up. Parents who see a high-SPF label on the bottle may think it’s safe to allow their kids hours of sunburn-free beach time, but risks associated with sun exposure begin in childhood and accumulate over a lifetime.
So the next time you tell me the firewall is like 70 SPF, I might ask A or B (e.g. are you just blocking the noise or also the attack). Here's another good example:
Consumers who shell out the bucks for pricey SPF-labeled moisturizers rarely get the sun protection they expect. There are plenty of sun care products that sell for less than $3 per ounce and offer better sun protection than those that cost up to 90 times more.
This quote is probably my favorite:
The front of a Lavera sunscreen box claims the product is “effective immediately” and there is “no need to wait.” But the side panel warns, “apply… 15 minutes before sun exposure.” Which is it?
Buyer beware. Don't judge a firewall by its cover.