Research by a community group worried about air quality has found that pollution levels are 30% higher at pushchair level than official recorded levels.
The group called hfcyclists worked with Healthy Air London and ClientEarth to monitor pollution levels at different heights. They attached pollution monitors at a variety of heights around two areas of west London.
Official readings are recorded three metres in the air but the study found levels of nitrogen dioxide (NO2) were higher at pushchair level.
NO2 is a noxious gas given out by petrol and diesel engines, but particularly diesel engines. It aggravates asthma, can stunt lung development and contributes to many deaths.
Recent research by Kings College London found air pollution caused the equivalent of 9,500 premature deaths in 2010. 5,900 of these were attributed to dangerously high levels of NO2.
Andrea Lee, Healthy Air London coordinator at ClientEarth, said: