Air Pollution: Outdoor Air Quality and Health

A recent report on road-traffic-related air pollution by the UK National Institute for Health and Care Excellence (NICE) urges for urban speed reduction to improve air quality.

Key takeaway:

  • A recent report on road-traffic-related air pollution by the UK National Institute for Health and Care Excellence (NICE) urges for urban speed reduction to improve air quality. NICE issues recommendations in seven areas: planning, development management, clean air zones, reducing emissions from public sector transport services and vehicle fleets, smooth driving and speed reduction, walking and cycling, and awareness raising.
  • Two key relevant recommendations for walking and cycling are: (1) Authorities should establish 20 mph speed limits without physical speed reduction measures and (2) To induce a greater shift from motorized travel to active travel, active travel must be supported.


  • Planning: Local and regional governments as well as transportation authorities should include air pollution in strategic planning processes (i.e., core strategies, local transport plans, environmental strategies, health and wellbeing strategies, etc.), which means incorporating zero- and low-emission transport, such as walking and biking.
  • Development management: New developments should mitigate air pollution induced by road-traffic by incentivizing active travel over motorized travel, supporting the use of zero- and low-emission vehicles, and ensuring ample street trees and vegetation.
  • Clean air zones: Local authorities should consider clean air zones that restrict or charge certain types of vehicles, support zero- and low- emission travel, include targets consistent with World Health Organization air quality guidelines, and reduce exposure to air pollution across the zone instead of just air pollution hotspots.
  • Reducing emissions from public transport services and vehicle fleets: Two important measures can be: (1) Educating drivers on reducing their vehicle emissions and (2) Making low-emission vehicles a criterion for the procurement of public sector vehicles.
  • Smooth driving and speed reduction: Instead of using physical speed reduction measures, smooth driving and speed reduction should be encouraged by using speed limits and average speed technology on the roadside, real-time information to inform drivers what the current optimum driving speed is, 20 mph speed limits, and signs that display a driver’s current speed.
  • Walking and cycling: The built environment should be supportive of walking and cycling to encourage and enable active transport. This includes providing bike route options away from polluted roads and providing as much space as possible between cyclists and motorized vehicles.
  • Awareness raising: Multi-pronged efforts including education, community engagement, and various kinds of outreach are necessary to raise people’s awareness about road-traffic-related air pollution and encourage behavior changes.


  • Those most vulnerable to air pollution include children, the elderly, those with chronic health problems, people of color, and people of lower socioeconomic levels. Therefore, reducing air pollution is an equity issue.
  • Interestingly, NICE does not call for using physical speed reduction measures in urban areas. This suggests that a combination of other approaches should be used, such as speed reduction public education campaigns, changes in street design and the built environment, and technological advances in vehicle safety systems (like Intelligent Speed Assistance). 
  • Changes in the built environment that make walking and cycling safer—from road traffic dangers, air pollution, and personal safety, too—are necessary to catalyze a greater modal shift to active transport.


  • The researchers examined evidence in expert testimony in three areas to formulate recommendations: (1) The epidemiology of air pollution and health, (2) National and local frameworks for action, and (3) The use of Euro Standards to control vehicle emissions.

National Institute for Health and Care Excellence. (2017). Air Pollution: Outdoor Air Quality and Health.

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