UK air pollution hits the headlines
Friday, 4 April 2014 at 3:15:PM
The smog in parts of the UK has been receiving a good deal of coverage in recent days, with southern and eastern England being particularly badly hit – see for example these items from the BBC and Sky News.
Saharan dust has been a component of this pollution, and has largely been the focus of attention – partly because it’s a tangible manifestation of what’s happening in the atmosphere, but probably also because of its relative unfamiliarity to many people. This dust, however, is just one of many components of the pollution, which includes combustion-derived particulates, carbon monoxide, ozone and nitrogen dioxide. A range of sources are responsible for these, with home-grown and imported emissions from the continent being the major culprits on this occasion.
With all this focus on dust, particulates and permanent gases, one might think that thermal desorption–gas chromatography – which with a few exceptions deals with volatile organic compounds containing at least two carbon atoms – doesn’t have much of a role to play. That would be to misunderstand the complexity of the situation.
For a start, particulate matter (PM) in the atmosphere is not all the same. As well as primary PM, which mostly arises from combustion of fuels and industrial processes, so-called secondary PM can arise because of the reactions of gases such as nitrogen oxides and sulfur dioxide with volatile organic compounds, especially in forested areas. Understanding the reactions that take place continues to be an important field of research in the atmospheric sciences, particularly because of its influence on cloud formation and the production of low-level ozone.
There has also been a lot of attention given to the VOC content of particulate matter itself. Polycyclic aromatic hydrocarbons (PAHs) are the biggest concern here, due to their known toxicity and cancer-causing properties. It turns out that the component of particulate matter that is derived from combustion of fuels (‘black carbon’) contains the largest amounts of PAHs. Inhaled directly into the lungs, these particles have both a physical effect on the body (lung function), and more insidious effects resulting from the chemical action of the PAHs, including lung cancer.
So although the headline of this pollution episode is the dust, look more closely and you find that a range of pollutants – including VOCs – are contributing to the poor air quality, both directly and indirectly.
David Barden received his Ph.D. in Organic Chemistry from Cambridge University in 2004, and during his time as an editor at the RSC wrote news pieces for Chemistry World on various scientific topics. He is now Technical Copywriter at Markes International, where he draws on the expertise of his colleagues to explain how new thermal desorption and mass spectrometry technologies can be applied to analyse volatile organic compounds in a wide variety of situations.
- For the use of thermal desorption to identify PAHs in vehicle exhaust particulate matter, see our Application Note 097.
- For an overview of the role of gas-phase VOCs in the atmosphere, take a look at this article by Dr Jonathan Williams at the Max Planck Institute for Chemistry in Mainz, Germany.
- For a brief overview of PM and its health effects, see this article published by the World Health Organisation.