Lots of controversy over the use of pepper spray on protesters, including controversy that led to the UC Davis Police Officers, seen in this incident here, being suspended for what looks to be fairly standard police use of spray:
I’m not going to jump on this particular condemnation bandwagon. If you have a bunch of people blocking access to a public resource, or occupying private property, who refuse to move, the use of force by the police to get them to move is both legally and morally justified. In that situation you have two choices, you can either remove them by forcibly removing them through physical force, which is statistically much more likely to cause lasting injuries, or to use pain compliance.
Pepper spray is highly irritating, but once decontaminated, there are not really lasting effects. It is a compliance tool. If you had a bunch of people blocking access to your house, would you not use force to remove them? In this case the protesters knew what was going to happen if they didn’t move, and volunteered to pay the price.