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The following is a list of commonly used transport and air quality terms.

A printable version [PDF, 114 KB] of these terms and definitions is also available.

A Definition
AQ Air quality
Air quality guidelines Minimum requirements that outdoor air quality should meet in order to protect human health and ecosystems
Airshed An area designated by a regional council or unitary authority for the purposes of managing air quality and gazetted by the Minister for the Environment
Ambient air The air outside buildings and structures
Annual average daily traffic (AADT)

The average daily vehicle count over a year in vehicles per day

B Definition
Background air quality

The level of a contaminant across the airshed from all sources. This includes contributions from natural sources (eg volcanoes, forest fires, wind-blown dust, etc) and from human-generated sources (eg industry, domestic heating and ‘remote’ roads).

For roading projects, background air quality excludes the contribution of nearby roads

Board of Inquiry (BoI) An independent body appointed to make a decision on a project of national significance
Busy local roads Roads with an AADT greater than 20,000 vehicles per day
C Definition
Carbon monoxide (CO) A colourless and odourless gas resulting from the incomplete combustion of fuels, eg petrol
Census area unit (CAU) An area classified by Statistics New Zealand for the purpose of the census. These areas are usually developed through the aggregation of smaller areas (meshblocks) to match suburbs and other local boundaries and areas
Certificate of fitness (CoF) A mandatory check to establish whether a commercial motor vehicle is road worthy
Comprehensive air quality technical assessment

A comprehensive assessment of the likely air quality impacts associated with the final design of the project.

This assessment may also be referred to a Tier 3 assessment, and follows earlier less detailed or generic assessments

Concentration The mass (weight) of a substance per unit volume, eg parts per million or milligrams per cubic metre
CAQMP Construction air quality management plan
Continuous monitoring Air quality monitoring undertaken by continuously collecting airborne gases or particles using a vacuum source in order to (usually) demonstrate compliance with an applicable regulation (eg a chemiluminescent NO2 analyser)
D Definition
Design year 10 to 20 years after the opening of a new or improved road
Designation A form of 'spot zoning ' over a site or route, provided in a district plan, for a project or public work
Diffusion tube A simple air quality monitoring device that absorbs pollutants over a period of exposure and is then analysed at a laboratory to determine pollution levels
Dust Fine, dry powder consisting of tiny particles of earth or waste matter lying on the ground or on surfaces or carried in the air
E Definition
Emission The release of a substance to air (eg the discharge of a pollutant from vehicle exhaust)
ESR Environmental and social responsibility
ESR screen

The screen is a tool that has been developed by the Transport Agency to identify potential environmental and social risks (including air quality) associated with roading project options.

The ESR screen is a high-level desktop assessment and is the first level of assessment in the development of a project. The ESR screen is equivalent to what is sometimes referred to as a Tier 1 assessment

EUD Environment and urban design
Exceedance A concentration of an air pollutant that exceeds a standard or criteria
Existing air quality The air quality prior to implementation of the project being assessed. It is generally considered the sum of background air quality and the nearby road contribution
Exposure The concentration of air pollution experienced by a person for a defined time period
Extinction coefficient (K) A measure of the ability of light to pass through air (opacity). The higher the extinction coefficient (expressed as m-1) the less light that will pass through air
G Definition
Government Policy Statement on Land Transport Funding (GPS) Sets out the government’s priorities for expenditure from the National Land Transport Fund over the next 10 years
Guideline value A concentration value against which air quality is assessed and managed
H Definition
Highly sensitive receptor (HSR) A location where people or surroundings may be particularly sensitive to the effects of air pollution, eg houses, hospitals, schools, childcare facilities, rest homes, and marae
%HV Percentage of heavy duty vehicles (ie vehicles with a gross vehicle mass of over 3.5 tonnes) as part of the overall traffic volume
L Definition
Land Transport Management Act 2003 (LTMA) The planning and funding framework that central government funding into roading construction and maintenance and public transport
Link A portion of a road between two intersections, junctions, interchanges or nodes. Its basic characteristics are length, vehicle speeds, travel times and the number of lanes
Local authority A regional council, unitary authority, local council or territorial authority
M Definition
Micrograms per cubic metre (µg/m3) A unit of concentration
Milligrams per cubic metre (mg/m3) A unit of concentration
Ministry for the Environment (MfE) The agency responsible for advising central government on stewardship of the New Zealand environment
Ministry of Transport (MoT) The government’s principal transport adviser, providing policy advice and support to Ministers
N Definition
National environmental standards for air quality (NES) Regulations made under the Resource Management Act 1991 which aim to set a guaranteed minimum level of health protection for all New Zealanders
Nearby roads Any state highways within 100 metres and any busy local roads within 50 metres of the area or project under consideration
Nearest equivalent roadside monitoring site A roadside monitoring site with comparable traffic flow and dispersion characteristics
Nitrogen dioxide (NO2) An air pollutant produced from the combustion of fuels, eg diesel
Nitrogen oxides (NOX) Collective term for the oxides of nitrogen, including NO2
Notice of Requirement (NoR) A notice given by a requiring authority (eg the Transport Agency) to a territorial authority (eg a city or district council) of the requirement for a designation for a public project or work. A proposed designation is referred to as a requirement for a designation
O Definition
Opening year The year in which the state highway improvement is completed and opened for public use
P Definition

Particulate matter (PM)



An air pollutant produced from the combustion of fuels, eg diesel, road dust and other human and other human and naturally-generated sources.

PM2.5 - particulate matter less than 2.5µm in diameter.

PM10 - particulate matter less than 10µm in diameter

Passive monitoring A method of air quality monitoring that does not use a mechanical method (eg a vacuum) for collection of an air sample. Diffusion tube monitoring is a common passive monitoring method
Preliminary air quality technical assessment

An assessment of the likely air quality impacts associated with a project or project options. This assessment is undertaken to indicate whether an air quality guideline or standard is likely to be exceeded and to scope the requirements for Comprehensive air quality technical assessment.

This assessment is equivalent to what is sometimes referred to as a Tier 2 assessment

R Definition
Receptor A location where any person (not just sensitive people) may be exposed to pollution from the road
Regional standards, targets and guidelines Limits set to maintain and enhance a particular level of air quality in a region
Resource Management Act 1991 (RMA) New Zealand's main piece of legislation that sets out how we should manage our environment
Reverse sensitivity The legal vulnerability of an established activity (eg a road) to complaint from a new land use or activity (eg a new residential development)
Roads of national significance (RoNS) Essential state highways identified by the Government as being linked to New Zealand’s economic prosperity
S Definition
Significance criteria Thresholds or triggers set to indicate whether it is likely that the project option under consideration will cause adverse air quality effects
T Definition
Total suspended particulate (TSP) A measure of likely dust nuisance that can arise from road construction activities

The Transport Agency classifies a fully enclosed roadway greater than 80m in length as a tunnel

W Definition
WHO World Health Organisation, a United Nations agency that is concerned with  public health
Warrant of fitness (WoF) A mandatory check to establish whether a private motor vehicle is road worthy

For further information contact