You will rarely see this report (authored by two of the world's leading scientific authorities on bear attacks) discussed by the heavy-caliber handgun crowd, so here are some numbers from the report to keep in mind:
"In 92% (46 of 50; G1 1⁄4 41.4, P , 0.001) of close-range encounters with brown bears, spray stopped undesirable behavior in which the bear was engaged. In 90% (18 of 20; G1 1⁄4 14.7, P 1⁄4 0.001) of close-range encounters with black bears, spray stopped the bear’s undesirable behavior. All bear-inflicted injuries (n 1⁄4 3) involved brown bears and were relatively minor (i.e., no hospitalization required). During 1985–1995, Herrero and Higgins (1998) found bear spray use in Alaska 94% effective overall (30 of 32 incidents; G1 1⁄4 31.3, P , 0.001); we found that in the decade following bear spray, efficacy was 90% (36 of 41 cases; G1 1⁄4 33.4, P , 0.001)."
Efficacy of Bear Deterrent Spray in Alaska Ah, but what about the wind, you say?
"Wind can influence bear spray’s accuracy and distance; however, our data show that wind rarely affected the outcome of bear–human interactions involving bear spray, which is likely because many close encounters do not occur in open areas, but rather in dense brush or forests where wind is greatly attenuated (T. Smith, Brigham Young University, unpublished data; S. Herrero, University of Calgary, unpublished data). High exit velocities of spray from cans likely compensates for cross-wind effects and may account for the low incidence of wind-related effects reported in Alaska. Of the 72 incidents we studied, 4 (6%) involved persons that had to leave the area to alleviate burning eyes and coughing. No one reported being incapacitated by spray, although one user said he had to move or he would have been overwhelmed."