Pepper Spray

Pepper Spray is an inflammatory agent. The effects are immediate and will normally last 30 to forty-five minutes depending on the strength of the spray. Independent tests have confirmed that pepper spray is harmless unless you are exposed to it frequently. Frequent exposure to pepper spray may result in sensitivity of the cornea but with no long term loss of visual acuity.

The Scoville Content is the best way to determine the strength of the spray.

When looking for a suitable pepper spray you should not just look at the percentage of OC in a spray to determine its strength. A percentage can be misleading because OC comes in different strengths (up to 2,000,000 SHU). It is the strength of the OC in a spray that tells how effective it will be and not the percentage in volume in the canister. Scoville Heat Units or SHU's is used to measure the strength of the OC before it is diluted with active ingredients. Therefore a pepper spray that has a 10% 2,000,000 SHU formulation means that 10% of the pepper spray in that canister has an OC rating of 2,000,000. Now that 2,000,000 SHU OC has been diluted by 90% active ingredients (propellant and carrier). So the entire forumlation does not have a SHU of 2,000,000, but 200,000.
In the above example 200,000 would be the Scoville Content of the Pepper Spray. Scoville Content measures the strength of the OC after is has been diluted.