It's a good read, providing a nice historical overview of how the helmet evolved and what it is designed to do and not to do. They also point out the "blame the victim" mentality of much media coverage of bicycle fatalities. Here's a nice little snippet, but read the whole thing, it isn't long.
I have been a bike commuter in every city I’ve lived in as an adult, including Minneapolis, Milwaukee, Chicago, Columbus, and New York City. I travel on two wheels for the exercise and fresh air, for environmental reasons, and for independent, efficient mobility.
In exchange, I feel unsafe, always, on my bicycle—and for sound reason. I’ve gotten doored in Times Square. I’m forced to weave in and out of bike lanes to avoid the vehicles that constantly park and loiter there. I hold my breath when a passing truck leaves only a few inches between my shivery flesh and its metal flanks.
I do what I can to protect myself. I use front and rear lights. I gravitate toward roads with designated bike lanes. I signal turns with my arms and ding my handlebar bells to attract the attention of inattentive drivers. And I never, ever leave home without my neon yellow helmet.
But as with many cyclists and lawmakers, I’ve increasingly found myself wondering: How much does my helmet help me, really? Are there costs to our single-minded devotion to it?
In the past 50 years, as helmet designs have become more sophisticated, adult cycling deaths in the United States have not declined—they’ve quadrupled. As I dug into the history of these humble foam-and-plastic shells, I learned that helmets have a far more complicated relationship to bike safety than many seem ready to admit.