In early 2022 the King County (Washington State) Board of Health voted to repeal their all-ages bicycle helmet law. This was a rare law requiring the use of bicycle helmets for all riders. One of the arguments in favor of repeal was that the law not a top reason that most people choose to wear a helmet. To test this assertion, Public Health-Seattle and King County conducted an observational study to assess helmet use 1 year after the repeal went into effect. Their count revealed that helmet use remains high across King County, especially for people riding their own bicycles. See full report.
Decades of research have repeatedly concluded that bicycle helmets are highly effective at preventing injuries and death.