I received the following email inquiry this morning:

____________

Mr Krizek,

Here is a response, fresh off the press from the book recently edited by John Parkin of the UK:

Kevin J. Krizek (2012). Cycling, Urban Form and Cities: What Do We Know and How Should We Respond? Cycling and Sustainability; Transport and Sustainability, Volume 1. John Parkin, editor. Chapter 5; 111-130. Emerald Group Publishing, UK.

…from page 121

“Some recent research on cycling aims to better understand unintended consequences linked with increased exposure to air pollution (Panis, 2011; Zuurbier et al., 2010). Despite the many virtues of cities for cycling, including relatively high land use densities, a drawback to cycle use is related to air quality and this becomes more important when the activity in question requires significant amounts of oxygen intake. Air pollution can affect the respiratory system because of the deep draw down of air into the lungs and may even lead to heart rate variability (Weichenthal et al., 2011). Of particular concern are ultrafine particulates. Hazards from air pollution are extremely localized and require close proximity (a very few metres), which is just the position of cycle traffic in relation to localized air pollution problems caused by motor traffic. Various treatments have been proposed such as separating cycle traffic from motor traffic by more than the requisite distance, allowing and encouraging bicycles to wait for a traffic signal green light in front of the queue of motor traffic (in so-called bicycle boxes or behind so-called advanced stop lines, which also then have the advantage that they allow cycle traffic a head start before motor traffic accelerates from a stop), or, through appropriate area wide traffic management to create a tiered system of routes with cycle traffic and motor traffic encouraged to use adjacent parallel routes. Overall, however, the evidence suggests that there are potential consequences to cycling in urban areas dominated by motor traffic that need to be addressed in order to avert the potential for cycling in cities being increasingly associated with health risks (Zuurbier et al., 2010).”