how strong is pepper spray?

My Mum had it once to protect our dog from other dogs. My older brother thought it'd be a good idea to spray it, I said "not in the house." So he sprayed it outside the backdoor, it stunk out the entire house from him spraying just outside the house, the dogs were choking my younger sister upstairs was choking.. The birds were fine for some reason, didn't affect them. But that stuff was potent.