Seasonal variation in cutaneous seat belt markings in fatal vehicle crashes

A retrospective review of autopsy reports of adult (>= 18 years old) vehicle occupants was undertaken at Forensic Science SSA (FSSA) over a five-year-period from January 2014 to December 2018 to correlate seat belt wearing with cutaneous seat belt injuries and season of the year. Out of 185 cases included in the study 134 vehicle occupants were wearing seat belts (72.4%) and, of these, 44 (32.8%) had seat belt markings across either the chest, the abdomen, or both. No significant differences were found in the incidence of seat belt wearing over the seasons: summer N = 37 (28%), autumn N = 28 (21%), winter N = 32 (24%) and spring N = 37 (28%); however, there was a significantly lower number of cases with markings in the colder months: summer N = 16 (36%), autumn N = 9 (20%), winter N = 4 (9.1%) and spring N = 15 (34%) (p = 0.027). It is unclear why there are fewer cutaneous markings from seat belts in the colder months of the year; however, it is possible that this may be related to reduced impact forces due to lower vehicle speeds during inclement weather, or to the wearing of more clothing during colder months which coincidentally acts as padding.