Some air rifles, side lever or bolt, if the lever or bolt is pulled back sufficiently a pellet can load (spring magazines) but then if your fingers slip from the bolt before the hammer catches the sear they will fire even with the safety on. A sear safety does not lock the hammer. I would like a cross hammer safety, something that can be engaged that would block the hammer from striking the exhaust valve poppet. Such a safety would also prevent unintended discharges from faulty trigger adjustment or sear damage.
Not to get to far into PBs but the Remington 700, one of the most popular bolt hunting rifles ever made uses a sear safety, the firing pin is not locked. This is quite common in numerous popular bolt rifles. The Mauser designs and others, my Kimber Mountain Ascent, there is a three postion safety on the bolt that locks the firing pin. Myself, right or wrong, unless a dangerous animal is about, would never carry a bolt rifle loaded. My Marlin 1895 lever guns have a hammer half cock position (exposed hammer) and there is (post 1983) a CBS (cross bolt safety) that prevents the hammer from being able to strike the firing pin. I will carry a lever rifle loaded with CBS engaged and hammer at half cock (safety). This feature possibly saved my brother when he was using a rope designed for the purposes to pull his Marlin 336 up to the tree stand, the rope slipped, the rifle hit a limb while pointed at him with enough force to shear the half cock notch but the firing pin was blocked by the CBS. I like the CBS and would love to have a CHS (cross hammer safety) for applicable air rifles. We cannot bring a bullet or pellet or slug back.
Edit to add, both me and my father and uncle soundly scolded my brother for attempting to pull a loaded rifle up into a tree stand. His excuse was his fingers were cold and he did not therefore unload the rifle. The best safety of all is the one that exists between the ears.
I know the fellow who sued Airforce after shooting himself in the foot. I forget the details except that it was his fault IMO. He was not fully familiar with the rifle and failed to understand how the mechanism worked. To repeat, the best safety is the one that exists between the ears.
These .22, .25 and .30 plus caliber air rifles are fully capable of killing or seriously wounding a human being.