How is Air Pollution Measured?

In 1997, the National Air Quality Strategy was implemented in the UK, encouraging local authorities to conduct comprehensive monitoring of air pollution in their areas. However, it might surprise you to know that air quality monitoring stretches back much further than that.

Coordinated efforts to track and assess quality levels of air across Britain have been in place in some shape or form since the early 1960s. In the 50 years that have passed, an evolution in environmental monitoring (with particular regard to the value of wireless data transmission) has occurred, meaning that we now have a more comprehensive overview of British air quality than ever before.

Types of Air Quality Monitoring

Currently, there are 1,565 sites measuring air quality through a variety of different criteria. Nine networks manage and collate this data, allowing us a valuable insight into the state of the air we breathe. These networks are as follows:

• Automatic urban monitoring network. With 104 sites measuring nitrogen dioxide (NO2), ozone (O3) and sulphur dioxide (SO3), this network continually measures air pollution in an urban setting and makes this information readily available to the public.
• Automatic rural monitoring network. Similar to the above network, the rural framework only has 18 sites, all of which measure O3 but only three of which measure SO2 and nitrogen oxides (NOx).
• Automatic hydrocarbon monitoring network. Also placed in urban settings, these sensor measure 25 hydrocarbons with a high potential for photochemical oxidant composition. Furthermore, the carcinogens 1.3-butadiene and benzene are monitored.
• SO2 and smoke monitoring network. A direct result of the Clean Air Act of 1956, this network was set up in the 1960s and now contains a total of 165 sites.
• NO2 diffusion tube monitoring network. NETCEN (formerly known as Warren Spring Laboratory) added diffusion tube monitoring equipment to 360 existing SO2 sites (mentioned above) throughout the UK in 1986 and 1991. In 1993, this figure was increased to 1,200.
• Acid deposition monitoring network. 32 sites around Britain currently monitor rain and other forms of precipitation to test for acidity and pollution. Precipitation is assessed for its pH levels, conductivity, anions and cations.
• Lead and multi-element monitoring network. From 1976, the volume of lead in the air is monitored through the joint efforts of four discrete networks. These are a) five multi-element monitoring sites in urban environments b) eight petrol-monitoring sites in various environs c) hotspot monitoring at nine industrial sites and d) four long-term rural sites. Meanwhile, the trace elements of cadmium, chromium, copper, iron, manganese, nickel and zinc are also measured at five more sites, which also offer secondary data on lead levels.
• Rural SO2 monitoring network. 38 sites in rural settings offer volumetric measurements of SO2 levels across the UK.
• Toxic organic micropollutants (TOMPS) monitoring network. 17 sites (15 of which are in an urban environment) deliver information on polycyclic aromatic hydrocarbons (PAHs) and dioxins.

All of this information together offers a comprehensive overview of the quality of air around the British Isles. Furthermore, the advent of open source, wearable monitors (such as those developed for the 2012 London Olympics) mean that citizens themselves can contribute to our understanding of air quality. As a result, we now have a better picture of the state of the air we breathe than ever before.