Nitrogen Dioxide (NO2) levels, measured using roadside diffusion tubes, are generally well below the UK national target for clean air, set at 40 μg/m3 (micrograms per cubic metre). In 2017, no roadside monitoring site in the Forest of Dean District failed to meet the UK objective. The most polluted site measured was on Lydney High Street, with a 2017 average NO2 concentration of 36.9 μg/m3.
