The NZ Transport Agency (NZTA) Air Quality Screening Model for estimating air quality near roadways combines the contribution of the road together with the background air quality to arrive at a cumulative concentration. The model is designed to provide a conservative (worst-case) assessment of air quality risk from a single road for two key transport-related air pollutants – particulate matter (PM10) and nitrogen dioxide (NO2). For more complex situations, specialist advice may be required.
The road contribution to PM10 and NO2 concentrations are calculated using Vehicle Emission Prediction Model (VEPM) emission factors, which take into consideration the assessment year, the average speed, the amount of traffic and the proportion of heavy vehicles. Background air quality data (excluding nearby roads) are available for every location in New Zealand (by census area unit). The background air quality data is provided on our website as an Excel spreadsheet.
Vehicle Emission Prediction Model
The screening model outputs which are used in a preliminary technical assessment are 24-hour PM10 and annual NO2 in line with the NZTA Guide to assessing air quality impacts from road transport projects (2019). The screening model can also be used to predict concentrations of annual PM10, 24-hour PM2.5 and annual PM2.5, however only annual NO2 and 24-hour PM10 are required within the preliminary technical assessment.
Guide to assessing air quality impacts from road transport projects [PDF, 1.9 MB]
The screening model is an Excel spreadsheet. The current version of the screening model is version 3.0.
Air Quality Screening Model [ZIP, 2.6 MB]
Additional user guidance is available in the Air Quality Screening Model user notes.
Air Quality Screening Model user notes [PDF, 1.3 MB]
For further information contact environment@nzta.govt.nz.
