The seat belt is one of the most effective ways to protect occupants in car crashes. Unfortunately, the average seat belt use in Europe (2018) was 83% for drivers and 81% for front seat passengers, where teenagers often have the lowest rate. The study aimed to use real-world car crashes to analyze the seat belt use among 0 to 18 year old children and teenagers as occupants and 18 to 20 year old drivers in Sweden 2011-2018. An additional aim was to analyze the effectiveness of seat belt reminders for both the front and the rear seats for the same age groups.

The Swedish Traffic Accident Data Acquisition was used, which is the Swedish national system for road traffic injury data collection. The data included 26 270 car crashes involving 30 447 car occupants in passenger cars. Regarding passengers, 5% were children aged 0 to 18 years and 12% of the drivers were aged 18 to 20 years.

Occupants aged 14 to 18 years had a lowest seat belt usage rate (89%), where the rate was even lower when these passengers had a young driver, 86% if the driver was aged 18 to 20 years and 93% if the driver was aged 30 years or above. And male passengers had a higher seat belt usage rate if they had a female driver, 94% if they had a female driver and 87% if they had a male driver. In the rear seat, children and teenagers aged 12 to 18 had a lowest seat belt usage rate and 18 year olds had the lowest (79%). The usage rate was lower when the passengers were sitting in the rear seat and when the driver was young.

For children above 8 years, seat belt use was higher in cars with an SBR. This was also the case for adults (over 30 years). There was a clear difference for the rear seat, especially for teenagers 14 to 18 years, among whom 100% used the seat belt in a seat with an SBR.

Young drivers had a higher risk to be involved in a road traffic accident compared to other age groups. Unfortunately, teenage passengers to these young drivers also have the lowest seat belt usage rate in the data. And there was indications that male teenage passengers have lower seat belt usage rate if their drivers also were male. One conclusion may be that the seat belt usage for a teenage passenger can depend on the driver. Therefore, it is important to put extra focus on this age group of drivers to increase seat belt use for their passengers

The present study clearly shows the need of actions aimed to increasing the seat belt use for rear seat passengers. The seat belt use in the rear seat is lower compared to the front seat, especially when the driver is young. The SBR has been shown to be effective in the front seat, and should therefore have the same specifications in the rear seat.