Birds have very little or no reaction to hot peppers/powders/sprays etc. They have very small olfactory sensors/receptors and are basically immune. Rodents (squirrels, rats, mice etc) are not immune, so hot pepper powder and such works very well on them, we shoot it into our crawlspace via a leafblower and it is a great deterrent. Same for my water heater compartment and other areas. It will keep rodents/raccoons/dogs/cats and many others out of an area like my crawlspace, old cars/trucks/storage buildings/laundry rooms etc. Birds simply have no reaction - everybody else - yes!

It works outside but does degrade quickly in the exposed areas.

Later yesterday afternoon, I put out fresh bird seed and peanuts for the Mourning Doves; sparrows and Snowy Woodpeckers that come to my back yard early each morning. I learned the hard way that I have to buy specially hot pepper treated feed for the birds, or the squirrels come and eat it all, while they chase the birds i want to appear, away. So this morning I got up early to fix my coffee by the kitchen window and looked out to see if the birds have arrived yet. Much to my surprise, there was a squirrel, right in the middle of a tray of bird seed and peanuts, getting ready to take a mouthful of especially treated bird food, guaranteed to be "squirrel proof." After quickly turning on my camera, I looked up in just in time to see the squirrel's mouth hanging open and a look on his face that caused me to burst out laughing. I only had time to expose one frame before he took off like his tail was on fire. When you look at the attached image, please try not to burst out laughing out of respect for the squirrel. He probably wished he had some cold milk to drink. After having the squirrels in my neighborhood consume massive quantities of untreated bird seed from my feeders, I learned that I had to buy specially treated bird seed to keep the squirrels away, in the future. I am having a problem feeling any sympathy for them. Do you feel that placing bird seed covered in hot pepper sauce to keep the squirrels from eating it all is sinful or just a necessary precaution brought on by the squirrels inconsiderate activities? (TEE Hee)

None. No effect on me or family members at all....usage requires a modicum of common sense, you would not put it in a play area, or inside in open areas. I don't spend anytime in my crawlspace, and if a repair requires a visit, a face mask (seem to have a couplle of those) would negate any effects. Obviously, you don't want it in high/regular traffic areas, but in places like crawlspaces/outbuildings/water heater compartments/attics/storage areas/old cars/trucks and other places we don't go, but the critters do. No need for poisons (or smeling the dead critters that ate the poison) just blow in some pepper powder every couple months and NO CRITTERS visit- I call it WIN WIN! A pound of cayenne pepper for $10 goes a long long way....