Evaluation and application of a statistical model for assessment of long-range transported proportion of PM2.5 in the United Kingdom and in Finland

Abstract

We have developed a simple statistical model for the estimation of the long-range transport (LRT) contribution to PM 2.5 concentrations. The modelling is based on linear regressions of the 'Co-operative programme for monitoring and evaluating the long-range transmission of air pollutants in Europe' (EMEP) background ionic components (SO 4 2À , NO 3 À , NH 4 + ) with the monitored PM 2.5 concentrations. We present an evaluation and application of the model against data measured in the United Kingdom (UK) and in Finland. We have studied the correlation of ion sum values with the PM 2.5 data measured at two EMEP stations in Finland (i.e., a comparison of ionic sum and PM 2.5 at one station). The statistical correlations of the PM 2.5 concentrations with the ion sum values were very high (R 2 varied from 0.77 to 0.83) at both of the stations considered; this provides confidence that the ion sum is a good proxy variable for the LRT PM 2.5 . The comparison of different modelling options using the data measured in the UK showed that the regression model gave systematically substantially better results than the model using merely sulphate concentrations. Similarly, using the distance weighted ion sum based on data from two EMEP stations gave better correlation, compared with the option of using only one EMEP station. The evaluated average LRT contribution accounted for 35-37% of the regional air PM 2.5 concentrations in UK from 1998 to 2000. The corresponding contributions at two urban stations in London were 24-31%. We conclude that the model is a useful and simple tool for the assessment of LRT PM 2.5 that is applicable within a fairly good accuracy. r

The effect of secondary inorganic aerosols, soot and the geographical origin of air mass on acute myocardial infarction hospitalisations in Gothenburg, Sweden during 1985–2010: a case-crossover study

“…PM ion (estimated sum of sulphate (SO 4 2− ), nitrate (NO 3 − ) and ammonium (NH 4 + ) ions) and the three individual ions were used as surrogates for LRT secondary PM [ 21 ].…”

“…where the subscripts S and N denote that the mass has been given as the equivalent mass of sulphur or nitrogen, respectively. In order to treat the particulate concentration variables in a comparable manner, these values were converted to equivalent masses of the SO 4 2− , NO 3 − and NH 4 + ions, using the conversion factors 3.0, 4.4 and 1.3, respectively [ 21 ]. The three ions were measured by IVL Swedish Environmental Research Institute on behalf of the Swedish Environmental Protection Agency, within the national air quality monitoring network at a rural background site located in Råö, 45 km south of the city centre [ 19 , 22 ].…”

Determinants of Personal Exposure to PM2.5, Ultrafine Particle Counts, and CO in a Transport Microenvironment

“…Traffic count was an insignificant determinant of PM 2.5 exposure concentrations in this study. The difference may be due the nature of the source of the pollutant, with long-range transboundary sources playing a greater role for PM 2.5 levels (25). Adams et al (14) found no consistent significant correlation between traffic count and the PM 2.5 exposure levels of road transport users in Central London, UK.…”

A review of operational, regional-scale, chemical weather forecasting models in Europe

“…Due to the extreme complexity of this issue, easy-to-use semi-empirical methods have also been proposed for evaluating the longrange transported fraction of PM 2.5 (e.g. Kukkonen et al, 2008).…”