Mobility Policy and Air Quality. The effect of a new bike lane and community space on air pollution: a real-world experiment in Berlin

Air pollution exposure in urban areas is a threat to human health. One of the largest sources of air pollution in urban areas is vehicles. This is particularly true for nitrogen dioxide (NO2) and underlines the need for a shift away from motorized individual transport toward healthy, sustainable transport. The paradigm shift - the Verkehrswende or Mobilitätswende (Traffic Transition or Mobility Transition) - as it has come to be called, has enjoyed broad support from citizens and decision- makers alike for decades, yet remains largely unrealized. Berlin was the first city to pass a Mobilitätsgesetz (Mobility Act). This law has many provisions to expand infrastructure for sustainable transport, such as supporting more cycling infrastructure, prioritizing cycling, walking, and public transit, and overall a more liveable, accessible city. To understand the effect of mobility policy on air quality, real-world experiments provide an opportunity to quantitatively assess the effect of such infrastructure changes on air quality. Here we found that the implementation of a bike lane reduced the concentrations of nitrogen dioxide that cyclists are exposed to. Furthermore, the small-scale repurposing of street space through a temporary Spielstrasse (community space) which closed a section of a street to vehicles to open the space for the community, also reduced air pollution during the occurrence of the community space. Such quantitative assessments of urban mobility policies can provide valuable information for policy decisions.