In regards to the proper care and feeding of chemical agents.

Don't store it in direct sunlight.  Check the canister for damage and leaks.  And take it out of service by the listed expiration date.  

That being said. let's mosy on to a similar topic.  

Oleoresin Capsicum.  O. C.  Pepper Spray.  Basically this is the "weaponized" version of a hot pepper.  The oils of the peppers converted by modern science into a pressurized agent used to disorient a subject.  It's almost as au-natural and hippie friendly as a hickory shampoo.  Ha ha, I kid, I kid.  

It is known as "less than lethal" due to the fact that it sits lower on the use of force chart.  However, "less than lethal" can be lethal at times without intent.  (See studies on positional asphyxiation in conjunction with use of chemical agents.)  Nothing is 100% safe.  (Remember that radio contestant who died from drinking water?)  

On that note, pepper spray is a bit of an area-of-affect tool.  Let's say that you are going hands on with an inmate.  Unless the situation goes pear shaped, you should not deploy pepper spray.  Not only are you hitting the inmate with the chemical, you are hitting the officers also.  Not every one is affected by O. C. the same way.  Take me for example.  I've had a lot of exposure to it and I can work through it.  Also, it makes me very angry.  And my anger is not directed at the inmate, but he officer who made a very poor decision.