<p>NO2 concentrations were measured during driving, walking and cycling commutes using Earthsense zephyrs. Four routes were taken.</p>
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<p>Measruements were averaged by trip and ratios of NO<sub>2</sub> in car to active commute (i.e NO<sub>2</sub> car/ NO<sub>2</sub> walking or NO<sub>2</sub> car/ NO<sub>2</sub> cycle) were calculated for each trip and route. </p>