title: Killer smog of London, 50 years on: particle properties and oxidative capacity.
abstract: Total suspended particulate (TSP) samples collected on glass fibre filters in London before (1955) and after (1958-1974) the Clean Air Act was examined for physicochemical characteristics and oxidative capacity. High-resolution microscopy identified most of the material as soot with smelter spheres, fly ash (FA), sodium chloride and calcium sulphate particles. Image analysis (IA) was used to show that most of the soot aggregates were less than 1 microm in size and contained chains of individual particles of 10-50 nm. Speed mapping of large agglomerates of the historic particles confirmed that the samples were enriched with soot probably derived from a sulphur-rich coal called nutty slack which was used extensively at this time. Inductively coupled plasma-mass spectrometry (ICP-MS) was used to examine elemental composition. Meaningful quantitation of certain elements (Mg, Al and Zn) proved impossible because they were in high quantities in the glass fibre filters. However, high quantities of Fe>Pb>Cu>Mn>V>As were detected which may explain in part the bioreactivity of the samples. Using a simple in vitro test of oxidative capacity (plasmid assay), one historic particulate sample (1958) showed three times the activity of a modern-day diesel exhaust particle (DEP) sample but ten times less activity than a modern-day urban ambient particle collection. Such studies are continuing to link particle physicochemical properties and bioreactivity with a wider range of the samples collected between 1955 and 74 and how such historic samples compare with present-day London ambient particles.
authors.affiliation: School of Biosciences, Cardiff University, Cardiff CF10 3US, Wales, UK.
authors.forename: Andy
authors.initials: A
authors.lastname: Whittaker
authors.forename: Kelly
authors.initials: K
authors.lastname: BéruBé
authors.forename: Tim
authors.initials: T
authors.lastname: Jones
authors.forename: Robert
authors.initials: R
authors.lastname: Maynard
authors.forename: Roy
authors.initials: R
authors.lastname: Richards
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects* / Q000266:history; D001681:Biological Assay; D049673:History, 20th Century; D006801:Humans; D008131:London; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010316:Particle Size; D010777:Photochemistry; D010957:Plasmids; D012905:Smog / Q000009:adverse effects*; D013048:Specimen Handling; D013054:Spectrophotometry, Atomic; D001335:Vehicle Emissions / Q000009:adverse effects* / Q000032:analysis
chemical_list: D000393:Air Pollutants; D012905:Smog; D001335:Vehicle Emissions