Nitrogen Dioxide in the Workplace Environment

Concentrations of nitrogen dioxide were measured in shops and car parks over a 19 week period during the winter. For the shops indoor:outdoor ratios varied from 0.34 to 0.54 with an average value of 0.44. NO2 levels ranged from 13 to 38 µg m-3. With little or no contribution from indoor sources, ambient concentrations are the primary factor in determining indoor levels. Concentrations of NO2 in car parks were similar to those measured at the kerb side. Concentrations in the payment booths were higher than those in shops and ranged from 42 to 60 µg m-3. Despite ventilation systems in the payment booths ratios of booth:car park NO2 varied from 0.65 to 0.86.