Air pollution monitoring: MARGA Network
The MARGA Network is named after the instrument it uses - the 'monitor for aerosols and gases in ambient air'.
The MARGA Network is part of the UK Eutrophying and Acidifying Atmospheric Pollutants (UKEAP) Network that monitors long-term pollutant trends in rural and remote locations.
It meets UK legal requirements for monitoring the chemicals in fine particulate matter (PM2.5).
PM2.5 are particles of solids or liquids in the air less that are than 2.5 micrometres in diameter. Particulate matter (PM10) are particles of solids or liquids in the air that are less than 10 micrometres in diameter. For context, the width of a human hair is 50 to 70 micrometres.
Data from the MARGA Network helps us:
- identify where air pollution comes from
- understand how air pollution carried over long distances by the wind contributes to PM2.5 in towns and cities
Monitoring stations
The MARGA Network has 2 monitoring stations:
- Auchencorth Moss in Midlothian, Scotland
- Chilbolton Observatory in Hampshire, England
Both these monitoring stations are in rural sites away from significant sources of air pollution.
Pollutants the MARGA Network measures
The MARGA network takes hourly measurements of:
- the major ions in PM10 and PM2.5
- gaseous pollutants
Major ions in PM10
The MARGA Network measures:
- ammonium (NH4+) in PM10
- calcium (Ca2+) in PM10
- chloride (Cl-) in PM10
- magnesium (Mg2+) in PM10
- nitrate (NO3-) in PM10
- potassium (K+) in PM10
- sodium (Na+) in PM10
- sulphate (SO42-) in PM10
Major ions in PM2.5
The MARGA Network measures:
- ammonium (NH4+) in PM2.5
- calcium (Ca2+) in PM2.5
- chloride (Cl-) in PM2.5
- magnesium (Mg2+) in PM2.5
- nitrate (NO3-) in PM2.5
- potassium (K+) in PM2.5
- sodium (Na+) in PM2.5
- sulphate (SO42-) in PM2.5
Gaseous pollutants
The MARGA Network measures:
- gaseous ammonia (NH3)
- gaseous hydrochloric acid (HCl)
- gaseous nitric acid (HNO3)
- gaseous nitrous acid (HNO2)
- gaseous sulphur dioxide (SO2)
- nitric oxide (NO)
- nitrogen dioxide (NO2)
Monitoring instruments and methods
The MARGA Network uses monitoring instruments that sample ambient (outdoor) air through a PM10 size-selective inlet head.
It uses ion chromatography to monitor concentrations of gas and the major ions in PM10 and PM2.5 in near real-time.
Ion chromatography is a laboratory technique used to measure dissolved substances in a liquid by separating them according to their electrical charge.
MARGA Network start date
The MARGA Network started on 17 February 2009.
Latest UKEAP annual report
The UKEAP annual report 2024 provides:
- network operation updates
- annual pollutant concentrations
- interpretation of data and trends
- a summary of scientific research, publications and other activities related to the network