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Automatic Hydrocarbon Network 

Introduction

Automatic hourly measurements of speciated hydrocarbons, made using an advanced automatic gas chromatograph (VOCAIR), started in the UK in 1992. By 1995, monitoring had expanded considerably with the formation of a 13-site dedicated network measuring 26 species continuously at urban, industrial and rural locations.  Currently there are 4 sites measuring 29 species continuously at urban and rural locations using an advanced automatic Perkin Elmer gas chromatograph.

What is measured?

Parameters Measured Monitoring sites and data
1,2,3-trimethylbenzene
1,2,4-trimethylbenzene
1,3,5-trimethylbenzene
1,3-butadiene
1-butene
1-pentene
2+3-methylpentane
2-methylpentane
3-methylpentane
benzene
cis-2-butene
cis-2-pentene
ethane
ethene
ethylbenzene
ethyne
iso-butane
iso-octane
iso-pentane
isoprene
m+p-xylene
n-butane
n-heptane
n-hexane
n-octane
n-pentane
o-xylene
propane
propene
toluene
trans-2-butene
trans-2-pentene
Current sites: 4
Total sites: 17
Data availability: 01/01/1993 to 22/11/2017

What is the purpose of the network?

The focus in this measurement programme is two-fold: firstly to assess ambient concentrations of a range of Volatile Organic Compounds (VOCs) with significant photochemical oxidant forming potential, and secondly to measure benzene for comparison with the Ambient Air Quality Objectives and 1-3 butadiene for comparison with UK Objective.

How is the network run?

The automatic hydrocarbon monitoring network, as originally constituted, used state-of-the-art measurement techniques, combined with advanced software techniques for signal processing and validation. It was the first network of its kind in the world. The Automatic Hydrocarbon Network operated successfully for 10 years before the programme was re-focussed, re-designed and simplified in 2002.

By 2008, the UK Automatic Hydrocarbon Network consisted of five sites, located at Glasgow, Harwell, London Eltham, London Marylebone Road and Auchencorth Moss. In 2011, the analyser at Glasgow was replaced with a non-automatic sampler reducing the number of sites to 4.  The Harwell instrument was relocated at the start of 2016.

Monitoring methods

The four monitoring stations are fitted with automatic Perkin Elmer gas chromatographs measuring a wide range of VOCs, equivalent to that studied under the original measurement programme. These instruments are capable of measuring and reporting at least 29 hydrocarbons.

Measurements from all four sites are reported to the European Commission, satisfying requirements under the Ozone Daughter Directive for monitoring photochemical ozone precursors. Corresponding benzene and the 1,3-butadiene data are used for comparison with the UK Air Quality Objectives, whilst benzene data are reported to the European Commission to fulfil requirements of the Air Quality Directive.

Hourly benzene and 1,3-butadiene data from all sites continue to be reported to the public through a range of web, electronic, text and broadcast media.

View data for sites in this network

Data can be downloaded from the Data Selector section of this website.

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Page last modified: 25 January 2017