An investigation into particulate air pollution in London, at a site on the Archway Road (A1) London

Samples were collected for several fractions of particulate matter (PM) at a roadside site - on The Archway Road (the A1) - in North London over a period of 6 weeks commencing 29/06/1998. Twenty-four hour samples were collected for Total Suspended Particulates (TSP) using a Rotheroe and Mitchell L30 pump. PM₁₀ , PM₂.₅, PM₁ fractions were monitored using a Partisol Starnet 2000 system (USEPA standard method for PM₁₀). Twenty-four hour Black Smoke (BS) samples were collected using an eight port BS sampler. Twenty four hour PM₁₀ was also collected using a portable
AirMetric MiniVol(TM) PM₁₀ monitor for comparison. Data collected for different fractions were analysed and compared. Comparisons were also made for the sub-sets of the data for weekends and weekdays.
The 24-hour PM₁₀ samples from both monitors were compared using regression analysis. Comparison of means suggested that the AirMetric readings were 110% higher than the Partisol readings. Both PM₁₀ data sets were regressed against Partisol PM₂.₅ data, indicating a 4.7% (& a fixed 2.2 μg error) on the part of the AirMetric monitor. Field controls showed that the AirMetric filter housings produced larger filter weight gains than the Partisol filter housings, this was accepted as being partly fixed error. Partisol data showed a PM₁₀: PM₂.₅: PM₁ ratio of 100:76:62, therefore, the equivalent PM₂.₅: PM₁ ratio was found to be 100:81. All PMIO data was found to be below the National Air Quality Standard (NAQS) limit of 50 μg m⁻³ with an average of 21 μg m⁻³. Both PM₁₀ and PM₂.₅ were found to compare well with data from other London roadside sites in terms of trends and concentrations. Rural sites were found to compare less well with consistently lower concentrations.
Twenty-four hour TSP was found to average 23 μg m⁻³, which was found to be low in comparison to published data. Rush hour data showed elevated average concentrations for both morning (RHAM) and evening (RHPM) samples of 40 μg m⁻³ and 42 μg m⁻³ respectively. Week day RHPM concentrations
showed more elevation than week end RHPM, whereas weekend RHAM rush hours showed highest levels with the maximum recorded concentration being a week day evening rush hour. Average BS concentrations were found to be 22 μg m⁻³ with slightly higher concentrations being found during
weekdays in comparison to week-ends. Regression analysis of all 24 hour data sets showed that BS had very weak relationships with all other fractions, whilst TSP displayed no relationships with other fractions and all PMx fractions were well corelated. Partisol errors were determined by regressing colocated PM₂.₅ data sets.

BSc Environmental Science and Technology