We could avoid breathing in dangerous polluting toxins like carbon monoxide by choosing where we walk and cycle more carefully, say researchers.
Researchers from the Faculty of Engineering at the University of Leeds studied carbon monoxide levels over an eight week period at one of the busiest junctions in the UK - the intersection between Marylebone Road and Gloucester Place in West London.
Their findings, published in the journal Atmospheric Environment, found found that air pollution levels change dramatically within small geographical areas like cities due to wind patterns, location of traffic queues and the architecture of surrounding buildings.
They found that pollution hotspots tend to accumulate on the sheltered, leeward side of the street and that carbon monoxide levels were up to four times lower in parallel side streets compared to the main road.
As such, pedestrians and cyclists could reduce their exposure to traffic pollution by simply crossing the street or changing their route slightly.
Researchers said local authorities and other bodies monitoring air quality levels in urban areas may now need to re-think how and where they collect data.
'Monitoring stations tend to be sited in what are expected to be pollution hotspots, but our research has shown that hotspots move depending on meteorological conditions, particularly wind direction,' said lead author Professor Alison Tomlin.
'We need to develop models which take these factors into account, so that the data from monitoring sites can be accurately analysed to provide a true reflection of air quality across the whole of an urban area.'