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Ambient air

The air outside buildings and structures. This does not refer to indoor air, air in the workplace, or contaminated air discharged from a source.

Critical level

The concentration in ambient air above which adverse effects may occur to vegetation.

Critical load

An exposure, in the form of deposition, to one or more pollutants, below which significant harmful effects on specified sensitive elements of the environment do not occur according to present knowledge.

Dispersion modelling

A computer modelling technique used to predict downwind concentrations of air contaminants from a known discharge rate, height and temperature.


The discharge of contaminants into the air.

Guideline value

Aconcentration value, and averaging period over which it applies, for assessing and managing ambient air quality.


Gathering to speak and share ideas and thoughts.


A contaminant that can be used as an indicator of other contaminants.


Home area, including dwelling and gardens.


Means the exercise of guardianship; and, in relation to a resource includes the ethic of stewardship based on the nature of the resource itself (section 2 RMA).

Mahinga kai

Food gathering, processing or preparation site.


Significant gathering area of whanua, hapu or Iwi-connected usually with an Ancestor

Maximum Design Concentration

A value specifying a concentration and averaging time that is used to assess the results of atmospheric dispersion modelling.


A statistical value that represents a distribution of data - in this case of ambient air concentrations. For example, the 99.9 percentile represents the ninth-highest result from a years worth of one-hour monitoring data.

Reduction strategy

One or more measures implemented through: regional air plans, policy statements, education programmes, incentive schemes, national regulations or national policies, to reduce emissions and manage air quality.

Reduction target

A percentage reduction in emissions required from different sources to achieve a guideline value or regional criteria.

Regional criteria

Region- or air shed-specific, concentration-based criteria specified in regional air quality plans or policy statements.


Geographical boundary and the land, features and people within it.

Target date

Date by which a council or other agency aims to achieve a specific regional criterion or guideline value.


Prized possession, treasure.

Waahi tapu

Sacred or significant site applying to various types of area. Iwi determines the use of the word.