P ACEVILLE STAMPEDE – A SCIENTIFIC BACKGROUND TO THE CASE 74 people were injured as a result of a stampede, which occurred last month. The probable causation of the stampede is the sudden overcrowding in a relatively small area, instigated when a man allegedly sprayed pepper or gas spray inside the premises. A stampede is initiated when people push tightly against each other in a confined space. A recent crowd management study suggests that during a stampede, 7 people end up in an area of 10 square feet. It is therefore imperative that in such instances, the individuals involved aim in maintaining the flow of passage. Failure of this will ultimately result in crushes. Crushes typically occur when members at the back of a large crowd continue pushing forward not knowing that those in front or at the sides are impeded by some force of hindrance. It is calculated that a crowd of only 6 to 7 people can exert a force of around 6,900kPa, the equivalent pressure able to cause the collapse of a brick wall. In stampedes shortness of breath is a common consequence, however during this event this was predominantly augmented due to the reported use of pepper spray inside the complex. Pepper spray is commercially available and usually comes in an aerosol can. The active ingredient oleoresin capsicum (OC), is an oily substance extracted from chili peppers which when mixed with a propellant, may be dispersed to target a wide area. Typical pepper sprays measure between 500,000 and 5,000,000 SHU, (Scoville Heat Units, a heat scale used to rate heat levels in peppers.) When relative to the 8,000 SHU of a jalapeùo pepper, the intense irritation may be approximated. Upon exposure to the spray, the immediate burning sensation of the eyes, nose and throat is sensed and once inhaled, the swelling of throat and eyes follows. Consequently, difficulty in breathing and simultaneous temporary blindness is experienced. The instilled physiological effect like the fear of the unknown, panic and anxiety can further lead to hyperventilation and temporary increase in blood pressure.