Which medical students pass out in the OR and why?

From a paper in BMC Medical Education:

Of the 630 clinical students surveyed, 77 responded with details of at least one near or actual operating theatre syncope (12%). A statistically significant gender difference
existed for syncopal/near-syncopal episodes (male 12%; female 88%), p less than 0.05. Twenty-two percent of those affected were graduate entry medical course students with the remaining 78% undergraduate. Mean age was 23-years (range 20 - 45). Of the 77 reactors, 44 (57%) reported an intention to pursue a surgical career. Of this group, 7 (9%) reported being discouraged by syncopal episodes in the operating theatre. The most prevalent contributory factors were reported as hot temperature (n= 61, 79%), prolonged standing (n=56, 73%), wearing a surgical mask (n=36, 47%) and the smell of diathermy (n=18, 23%).