Air Quality Monitoring Station

The North Sydney air quality monitoring station (AQMS) is located in the grounds of St Leonards Park, North Sydney .

Access the AQMS online here


The station is operated by SLR consulting on behalf of North Sydney Council. This location was selected as:

  • It is open enough to achieve compliance with the relevant siting criteria;

  • It is located in close proximity of the proposed Western Harbour Tunnel stack;

  • A high frequency of winds (approximately 28% based on meteorological modelling) blows from the location of the proposed Western Harbour Tunnel stack towards the site; and

  • It has sufficient space available for the AQMS without significantly impacting on other site uses.

The following air pollutants and meteorological parameters are currently measured by the AQMS:

  • Oxides of nitrogen (NO, NO2 and NOx)

  • Particulate matter less than 10 micron is size (PM10)

  • Particulate matter less than 2.5 micron is size (PM2.5)

  • Wind speed and wind direction

  • Ambient temperature

  • Relative humidity

  • Barometric Pressure

  • Solar radiation


A brief description of the measured parameters and how the data are presented on the North Sydney AQMS public dashboard is provided below.


Oxides of Nitrogen

NOX is a general term used to describe any mixture of nitrogen oxides formed during combustion.

In atmospheric chemistry, NOX generally refers to the total concentration of nitric oxide (NO) and nitrogen dioxide (NO2). NO is a colourless and odourless gas that does not significantly affect human health. However, in the presence of oxygen NO can be oxidised to NO2­, which can have significant health effects, including damage to the respiratory tract and increased susceptibility to respiratory infections and asthma. The atmospheric chemistry of NO to NO2 conversion is very complex and involves multiple chemical reactions, with the individual reaction rates varying depending on a range of factors such as background pollutant concentrations and the amount of sunlight. 

The ambient air quality standards for NO2 established by the National Environment Protection Measure for Ambient Air (NEPM) and adopted by the NSW EPA are as follows:

  • 1-hour average concentration: 12 pphm (120 ppb)

  • Annual average concentration: 3 pphm (30 ppb)

NO, NO2 and NOx are currently measured continuously by the North Sydney AQMS using a Chemiluminescence monitor in accordance with Australian Standard AS 3580.5.1-2011. The hourly data captured by the monitor is presented on the public dashboard as a line graph and table.


Particulate Matter

Particulate matter with an aerodynamic diameter of 10 microns or less is referred to as PM10.  The PM10 size fraction is sufficiently small to penetrate the large airways of the lungs, while PM2.5 (2.5 microns or less) particulates are generally small enough to be drawn in and deposited into the deepest portions of the lungs.  Potential adverse health impacts associated with exposure to PM10 and PM2.5 include increased mortality from cardiovascular and respiratory diseases, chronic obstructive pulmonary disease and heart disease, and reduced lung capacity in asthmatic children. 

The majority of particulate matter emitted from combustion processes, including bush fires and emissions from vehicle exhausts, is the PM2.5 fraction, while mechanically-generated dust from brake and tyre wear and dust storms have a higher proportion of particles in the PM2.5 – PM10 range.

The ambient air quality standards for PM10 and PM2.5 established by the NEPM and adopted by the NSW EPA are as follows:

  • 24-hour average PM10 concentration: 50 µg/m3

  • Annual average PM10 concentration: 25 µg/m3

  • 24-hour average PM2.5  concentration: 25 µg/m3

  • Annual average PM2.5 concentration: 8 µg/m3

PM10 and PM2.5 are currently measured continuously by the North Sydney AQMS using Tapered Element Oscillating Microbalance (TEOM) instruments in accordance with Australian Standards AS 3580.9.8-2008 and AS 3580.9.13-20013 respectively. The 24-hour average data captured by the monitor is presented on the public dashboard as a bar graph and rolling 24-hour average data is presented as a table.


Wind Speed and Wind Direction

Wind speed and wind direction are currently measured continuously. The hourly data is presented on the public dashboard as a table and a daily summary of wind speed and wind direction measurements for the last 24-hours is presented as a wind rose.

Wind roses show the frequency of occurrence of winds by direction and strength.  The bars correspond to the 16 compass points.  The bar at the top of each wind rose diagram represents winds blowing from the north (i.e. northerly winds), and so on.  The length of the bar represents the frequency of occurrence of winds from that direction, and the widths of the bar sections correspond to wind speed categories, the narrowest representing the lightest winds.  Thus, it is possible to visualise how often winds of a certain direction and strength occur over the 24-hour period.


Ambient Temperature, Relative Humidity, Barometric Pressure and Solar Radiation

Ambient temperature, relative humidity, barometric pressure and solar radiation are also currently measured continuously. The hourly data is presented on the public dashboard as line graphs and a table.



% percent
°C degrees Celsius
µg/m3 microgram per cubic metre
AQMS Air Quality Monitoring Station
hPa hectopascal, a meteorological unit of pressure
km/hr kilometres per hour
NEPM National Environment Protection Measure
NO nitric oxide
NO2 nitrogen dioxide
NOX oxides of nitrogen
PM10 particular matter with an equivalent aerodynamic diameter of 10 microns or less
PM2.5 particular matter with an equivalent aerodynamic diameter of 2.5 microns or less
pphm parts per hundred million (108)
ppb parts per billion (109)
W/m² Watts per square metre



absolute humidity The mass of water vapor divided by the mass of dry air in a volume of air at a given temperature.
ambient Pertaining to the surrounding environment or prevailing conditions.
ambient air quality standard The prescribed level of a pollutant in the outside air that should not be exceeded during a specific time period to protect public health.
atmosphere A gaseous mass surrounding the planet that is retained by Earth's gravity. It is divided into five layers, with most of the weather and clouds found in the first layer.
atmospheric Relating to the atmosphere
barometric pressure The pressure within the atmosphere of Earth
combustion The process of burning. A chemical change, especially oxidation, accompanied by the production of heat and light.
meteorological The science that deals with the phenomena of the atmosphere, especially weather and weather conditions.
particulate Of, relating to, or formed of minute separate particles. A minute separate particle, as of a granular substance or powder.
pollutant A substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource.
relative humidity The ratio of the current absolute humidity to the highest possible absolute humidity
solar radiation The power per unit area (watt per square metre), received from the sun in the form of electromagnetic radiation
wind direction The direction from which the wind is blowing.
wind rose A meteorological diagram depicting the distribution of wind direction and speed at a location over a period of time.



Posted on 1 April 2020

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