Elsevier

Atmospheric Environment

Volume 45, Issue 26, August 2011, Pages 4442-4453
Atmospheric Environment

Variation in characteristics of ambient particulate matter at eight locations in the Netherlands – The RAPTES project

https://doi.org/10.1016/j.atmosenv.2011.05.035Get rights and content

Abstract

Numerous epidemiological studies have shown health effects related to short- and long-term exposure to elevated levels of ambient particulate matter (PM). It is not clear however which specific characteristics (e.g., size, components) or sources of PM are responsible for the observed effects.

The aim of RAPTES (Risk of Airborne Particles: a Toxicological–Epidemiological hybrid Study) was to investigate which specific physical, chemical or oxidative characteristics of ambient PM are associated with adverse effects of PM on health. This was done by performing experimental exposure of human volunteers to air pollution at several real-world settings that had high contrast and low correlation between several PM characteristics.

For this goal, eight sites in the Netherlands that differed in local PM emission sources were chosen for extensive air pollution characterization. Measurement sites included an underground train station, three different road traffic sites, an animal farm, a sea harbor, a site located in the vicinity of steelworks, and an urban background site. Five- to six-hours average concentration measurements at each site were made between June 2007 and October 2009. We measured PM10, PM2.5, particle number concentration (PNC), oxidative potential of PM, absorbance, endotoxin content, as well as elemental and chemical composition of PM, and gaseous pollutants concentrations. This paper presents a detailed characterization of particulate air pollution at the sampling sites.

We found significant differences in all PM characteristics between the sites. The underground train station, compared to each outdoor location, had substantially higher concentrations of nearly all PM characteristics. The average PM10 and PM2.5 mass concentrations at the underground train station were 394 μg m−3 and 137 μg m−3, respectively, which was 14.1 and 7.6 times higher than the urban background. The sum of the concentrations of trace metals in fine and coarse PM was nearly 20 times above the outdoor levels. Elemental carbon (EC) was elevated at the underground site in the fine but also in the coarse mode, in contrast to the traffic sites where EC was predominantly found in fine PM. The highest concentrations and contrasts in PNC were at the traffic sites (between 45,000 and 80,000 particles cm−3), which was several times higher than measured at any other site. Correlations of PNC with metals, PM10, PM2.5 and absorbance were low to moderate, while correlations between PM10, PM2.5 and the metals Cu and Fe were high. After excluding the underground train station data, correlations between PM10, EC and metals decreased whereas the correlation between PNC and EC increased.

We conclude that we were able to successfully identify and characterize real-world situations with very different particle characteristics. High contrast and low correlations between PM characteristics, as well as consistency of these differences across sampling campaigns, provide a good basis for identifying health relevant PM characteristics in the upcoming analysis.

Highlights

► We successfully identified and characterized real-world situations with very different PM characteristics. ► Underground train station had the highest concentrations of almost every PM characteristic. ► Correlations between PM characteristics were low enough to investigate their independent health effects.

Introduction

In recent years numerous epidemiological studies have shown health effects related to short- and long-term exposure to elevated levels of ambient particulate matter (PM) (Brunekreef and Holgate, 2002, Pope and Dockery, 2006). These observations are supported by findings from controlled human exposure studies, animal toxicology and mechanistic in vitro studies (Maier et al., 2008, Lippmann and Chen, 2009).

Apart from regulated PM10 and PM2.5 mass concentrations, only a small number of PM characteristics are measured. Health effects have been mostly associated with the PM mass concentration and in few studies with specific PM characteristics such as number concentration, surface area, elemental and chemical composition, or oxidative potential (WHO, 2007, Brunekreef, 2010). Additionally, in epidemiological studies high correlations are typically present between the constituents (particulate as well as gaseous) of the air pollution mixture, which makes it difficult to disentangle their independent effects on human health (Brunekreef and Holgate, 2002).

A recent World Health Organization workshop (WHO, 2007) on the health relevance of PM from various sources suggested that future research should, among other things, (1) explore “the role of various characteristics of ultrafine, fine and coarse thoracic particles that might be responsible for health effects, (2) consider “the contributions of different emissions sources to population exposure”, (3) consider “other biological effects in the studies, beyond classically measured mortality or respiratory function and symptoms”, (4) ensure “that the exposure levels used in toxicological studies correspond to the components and levels of exposure experienced by populations and evaluated by epidemiological studies”, and (5) promote “an integrated study approach, combining detailed characterization of exposure, epidemiological observation of effects in populations and toxicological or clinical evaluation of the effects”.

We attempted to address these recommendations in the RAPTES project (Risk of Airborne Particles: a Toxicological–Epidemiological hybrid Study). The overarching aim of RAPTES was to combine real-world exposure conditions with an experimental exposure design so that health effects could be associated with specific ambient PM characteristics. In order to achieve this, we performed an extensive exposure assessment and characterization of physical, chemical and oxidative properties of PM at sites which were selected to provide high contrast and low correlation between PM characteristics and between contributing sources. At selected sites health effects were investigated in a panel of volunteers. PM samples were also collected for in vivo and in vitro experiments to investigate the mechanisms behind the health effects.

In this paper we present a detailed characterization of air pollution at the selected sites focusing on particulate air pollution and the contrast and correlations between its physical and chemical characteristics. The associated health impacts will be presented in subsequent publications.

Section snippets

Sampling site selection

We selected sites anticipated to provide a large contrast in exposure to specific characteristics of PM as well as a low correlation between PM characteristics, based upon previous studies of specific sources. The characteristics we took into account were mass concentration of particles less than 10 μm and less than 2.5 μm in aerodynamic diameter (PM10 and PM2.5, respectively) as well as the mass concentration of coarse PM fraction (PM2.5−10), particle number concentration (PNC) as a proxy for

Results

We completed 60 visits in total. Data from one day at the truck traffic site were not included in the analysis, due to a sudden weather change which interrupted the sampling. Data from four other sampling days were not included as they did not meet the specific criteria, particularly main wind direction from the source to the site. In total, 55 days were included in the analysis (Table 1).

Distribution of air pollution concentrations across the sampling locations is presented in Table 2 and

Discussion

We performed a detailed characterization of particulate air pollution at eight locations in the Netherlands. We found significant differences in PM characteristics between the sampling sites in a complex set of air pollution concentration measurements. The underground train station, compared to each outdoor location, had substantially higher concentrations of almost every PM characteristic, including PM mass, EC and trace metal concentrations, while the traffic sites had the highest particle

Conclusions

We conclude that we were able to successfully identify and characterize real-world situations with very different particle characteristics. High contrast and low correlations between PM characteristics, as well as consistency of these differences across sampling campaigns, provide a good basis for identifying health relevant PM characteristics in the upcoming analysis.

Acknowledgments

We would like to thank John Boere, Paul Fokkens, Daan Leseman (RIVM), Kees Meliefste (IRAS) and students: Lise van den Burg, Veerle Huijgen, Maartje Kleintjes, Marja Meijerink and Jet Musters for their help with data collection.

The RAPTES project was funded by the RIVM Strategic Research Program (SOR).

References (34)

  • H.-J. Jung et al.

    Source identification of particulate matter collected at underground subway stations in Seoul, Korea using quantitative single-particle analysis

    Atmospheric Environment

    (2010)
  • M.J. Nieuwenhuijsen et al.

    Levels of particulate air pollution, its elemental composition, determinants and health effects in metro systems

    Atmospheric Environment

    (2007)
  • C. Oliveira et al.

    Road traffic impact on urban atmospheric aerosol loading at Oporto, Portugal

    Atmospheric Environment

    (2010)
  • J.-C. Raut et al.

    Link between aerosol optical, microphysical and chemical measurements in an underground railway station in Paris

    Atmospheric Environment

    (2009)
  • I. Salma et al.

    Time-resolved mass concentration, composition and sources of aerosol particles in a metropolitan underground railway station

    Atmospheric Environment

    (2007)
  • D. Westerdahl et al.

    The Los Angeles International Airport as a source of ultrafine particles and other pollutants to nearby communities

    Atmospheric Environment

    (2008)
  • W. Birmili et al.

    Trace metal concentrations and water solubility in size-fractionated atmospheric particles and influence of road traffic

    Environmental Science & Technology

    (2006)
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