How Bear Spray Works

Bear spray isn't unlike pepper spray that humans use to protect themselves from other humans. The main difference is that bear spray can shoot farther and casts a wider effective area. There are three main ingredients in bear spray:

These ingredients are packed into a canister with a trigger and safety to make sure that no unwanted sprays occur. There are six bear sprays currently registered with the Environmental Protection Agency (EPA), and they each have variations depending on what you're looking for. There are four such variations for you to consider when picking out your spray:

When choosing your spray, you need to decide what's most important for you. A blast that shoots 40 feet (12 meters) might make you feel safer from a fast-charging black bear, but it will run out sooner than one that only shoots 25 feet (7.6 meters). There's a group of bear experts called the Interagency Grizzly Bear Committee (IGBC) that made some recommendations for purchasing bear spray in 1999. They believe that a spray that reaches 25 feet (7.6 meters) or more and that lasts for at least six seconds at a minimum of 7.9 ounces is the way to go. Who are we to argue? Out of the six approved brands, only three met these recommended standards, so be sure to read up on brand specifications before you buy some spray and hike fearlessly into the woods.

It's also a pretty good idea that you buy a canister holster to wear on your person. What good is a $45 shot of "Counter-Assault" spray if it's stuck in the bottom of your backpack when Yogi and Boo Boo arrive? You might as well just cover yourself in gravy and lie down on the trail.

Let's say a bear approaches you in the woods. You should make a lot of noise -- blow a whistle if you have one or bang on some pots and pans. Wave your arms above your head to appear larger and more intimidating and back away slowly while avoiding eye contact. Under no circumstances should you ever run from a bear. This will inspire it to run after you and even though they're large, they can hit speeds of up to 30 plus miles per hour (48 kph). When all else fails, reach for the spray, flip the safety off, take aim and fire away. A yellowish cloud will shoot out, and ideally the bear will either get hit straight in the face or run into the cloud. Try and account for wind as best you can -- this is really the only variable unless you're being attacked by multiple bears. If that's the case, try your best to hit both of them.

If you're able to hit the bear in the face, you're in business. Most likely the bear will make an instant, confused retreat. It won't knock a bear out, but it will definitely make it forget it wants to eat you. Capsaicin has the same effect on bears that it does on humans. They'll feel an instant burning sensation wherever you hit them, so just like humans, it's best to get them in the face. The eyes, nose and lungs will all burn like fire, causing the mucous membrane tissues to swell.

A face hit almost guarantees temporary blindness and big-time breathing problems. But the good news is that the sting will eventually subside and by that time, either you or the bear are long gone. You have all your limbs in tact, and the bear suffers no permanent damage. The same can't be said about bullets.

What can be said for bullets? They don't always thwart an attack. The U.S. Fish and Wildlife Service investigated human and bear encounters from 1992 to 2005 and found that people who defended themselves with firearms were injured about 50 percent of the time by the bear. People who used the bear spray escaped injury 98 percent of the time, and the few injuries they suffered were far less severe than those in the gun-toting realm. Why? Because it's difficult to stop a bear with a gun and wounded bears are more likely to become even more aggressive.

Another study was performed by Thomas Smith, a bear biologist from Brigham Young University. After analyzing 20 years of bear incidents, he found that bear spray was effective 92 percent of the time, compared to 67 percent for guns. Add to this that you can't bring guns into many national parks, and it seems like the spray is the best way to go.

Research has shown that it takes an average of four direct hits with a bullet to stop a bear [source: Science Daily]. Do you feel like you're a good enough shot to pull this off when a 600-pound (272-kg) grizzly is coming at you at 35 miles per hour (56 kph)? Accuracy isn't nearly as important with bear spray since you're shooting a wide cloud of smoke at your threat. Wind may be an issue, but the Wildlife Service study found that it only affected the shot 7 percent of the time and in each case, the spray still reached the bear. If you happen to shoot yourself or a friend as well, the effect of the bear spray will be the same as human pepper spray and will wear off after a few hours of discomfort.