.Use of PPE is a mitigation strategy and is less prominent or even absent where cycling risk is low (Pucher and Buehler 2008). Correspondingly, at population level helmet wearing is inversely associated with cycling safety; worn by fewer than 1% of adult cyclists and 3-5% of children in the safest country, The Netherlands (Pucher and Buehler 2008: 509). This does not mean helmets increase the risk of injury: there is broad scientific consensus that wearing a helmet may reduce the risk or severity of a head injury in certain collisions (Hagel and Pless 2006). Rather it signals a potential difference between individual level PPE-focused strategies, and population level approaches (for example, infrastructure that separates cyclists from heavy motor vehicles, reduced speed limits). Wearing a helmet may well confer some protection against head injury on the individual concerned. However, there is a lack of evidence that population increases in helmet use have led to reductions in population injury rates. Alternative population-level strategies are likely to provide much greater reductions in individual risk (Goldacre and Spiegelhalter 2013).
For high-visibility clothing, evidence of safety benefit has not been established at either the individual or population level. Although such clothing appears to increase visibility in artificial test situations (Kwan and Mapstone 2004), a systematic review did not identify ‘real world’ evidence that the use of ‘conspicuity aids’ is associated with reduced injury risk (Kwan and Mapstone 2009). Subsequent work has not provided clear evidence of benefit (Miller 2012, Tin Tin et al 2014, Walker et al 2014).