Urban Background PM10 Research Articles

Monitoring road traffic participants' exposure to PM10 using a low-cost system

The paper presents the application of a low-cost system for monitoring the current level of road traffic participants' exposure to PM10 air pollution. The research was carried out from the end of August 2017 to the beginning of October 2017 on the central section of one of the main roads in Bielsko-Biała, Poland. In the analysed period, significant changes in the daily distribution of road traffic both into and out of the city centre were observed. The average travel time depended on the direction of traffic, and the difference between directions being almost 50%. The PM10 urban background concentration was also subject to daily changes, and in the fifth week of observation, it reached a value more than twice as high as in the first week of observation. The maximum level of road traffic participants' exposure was observed at a relatively low urban background PM10 concentration. It was observed that a significant slowdown in traffic in conditions of acceptable urban air quality led to a comparable level of exposure to that of standard traffic conditions and poor urban air quality. It was also found that the slowdown in traffic increased the exposure time of traffic participants travelling towards the city centre by an average of 24% and, for those travelling in the opposite direction, by as much as 50%. In an extreme case of traffic delay, exposure to PM10 concentration in the vicinity of the road was two and a half times as long.

Comparative study of bulk and partial digestion methods for airborne PM10-bound elements in a high mineral dust urban site in Constantine, Algeria

ABSTRACTWhen high mineral loads in atmospheric particulate matter (PM) are present, particular attention should be paid to the selection of appropriate acidic digestion protocols for wet chemical analysis. We report on a comparative study of elemental recovery yields from five different pre-analytical acid digestion procedures for mineral-rich urban background PM10 samples collected in the city of Constantine (Northeastern Algeria). Five reference materials (NIST 1633b, UPM 1648, NAT-7, SO-2 and SO-4) were also digested according to the same protocols. The selected acidic digestion/extraction procedures are widely used for PM chemical analysis and comprise P1 (HNO3/HF/HCl), P2 (HCl/HNO3), P3 (HCl/H2O2/HNO3), P4 (HNO3/HF/HClO4) and P5 (HNO3/H2O2); the latter assisted with microwave digestion. Elemental recovery yields were compared for major and trace elements typically determined in PM for source apportionment analysis and the results evidenced large differences. For most elements, the bulk extraction procedures (requiring the use of HF) allowed a full elemental recovery, particularly for elements that are associated with aluminium silicate species and oxides that are resistant to mild acid attack. In contrast, in the extraction protocols without HF low recovery yields were obtained for elements such as Al, Ti, Zr, Sc and other aluminium silicate-related elements in PM10 samples with high mineral dust load. We highlight that the European standard digestion method EN-14902:2005 should be applied specifically for the metals for which this method was developed, but caution should be taken when the analysis of other elements in PM is required, especially in urban areas where road and vehicle wear dust is likely to be a major component of ambient PM. When using wet chemistry analysis for PM source apportionment studies, we strongly recommend HF bulk dissolution of samples to ensure the reliability of the geochemical information when coupled with an appropriate analytical tool.

A quantitative estimation of the exhaust, abrasion and resuspension components of particulate traffic emissions using electron microscopy

The contribution of the three traffic-related components exhaust, abrasion, and resuspension to kerbside and urban background PM10 and PM1 levels was quantified based on the analysis of individual particles by scanning electron microscopy. A total of 160 samples was collected on 38 days between February and September 2009 at a kerbside and an urban background station in the urban/industrial Ruhr area (Germany). Based on size, morphology, chemical composition and stability under electron bombardment, the 111,003 particles studied in detail were classified into the following 14 particle classes: traffic/exhaust, traffic/abrasion, traffic/resuspension, carbonaceous/organic, industry/metallurgy, industry/power plants, secondary particles, (aged) sea salt, silicates, Ca sulfates, carbonates, Fe oxides/hydroxides, biological particles, and other particles. The traffic/exhaust component consists predominantly of externally mixed soot particles and soot internally mixed with secondary particles. The traffic/abrasion component contains all particles with characteristic tracer elements (Fe, Cu, Ba, Sb, Zn) for brake and tire abrasion. The traffic/resuspension component is defined by the mixing state and comprises all internally mixed particles with a high proportion of silicates or Fe oxides/hydroxides which contain soot or abrasion particles as minor constituent. In addition, silicates and Fe oxides/hydroxides internally mixed with chlorine and sulphur containing particles were also assigned to the traffic/resuspension component. The total contribution of traffic to PM10 was found to be 27% at the urban background station and 48% at the kerbside station, the corresponding values for PM1 are 15% and 39%. These values lie within the range reported in previous literature. The relative share of the different traffic components for PM10 at the kerbside station was 27% exhaust, 15% abrasion, and 58% resuspension (38%, 8%, 54% for PM1). For the urban background, the following relative shares were obtained for PM10: 22% exhaust, 22% abrasion and 56% resuspension (40%, 27%, 33% for PM1). Compared to previous publications we have observed a significantly lower portion of exhaust particles and a significantly higher portion of resuspension particles. The high abundance of resuspension particles underlines their significance for the observed adverse health effects of traffic emissions and for mitigation measures.

Estimation of the long-range transport contribution from secondary inorganic components to urban background PM10 concentrations in south-western Sweden during 1986–2010

The contribution of long-range transported (LRT) to urban background PM10 concentrations was investigated from a long-term view from 1986 to 2010. Regional air concentrations of sulphate (SO42−), nitrate (NO3−), and ammonium (NH4+) were used as a sum (Cion) to investigate the contribution from these ions to the LRT PM10 concentrations at an urban background site in Gothenburg, Sweden. Utilizing backwards trajectory analysis, the LRT contribution from Cion to the urban background PM10 concentrations (LRTCion) was estimated for six unique transport pathways and related source areas. Air masses transported over eastern Europe, UK/North Sea/Denmark and the vicinity of Scandinavia were associated with high Cion concentrations observed in Gothenburg. For each pathway, multiple linear models based on the Cion concentrations were used to estimate LRTCion and PM10 at the urban background site. The performances of the multiple linear models were satisfying with R2 between estimated and observed annual mean PM10 concentrations of 0.81 during the monitoring years 1990–2010. The models were able to describe the main features of the day-to-day average PM10 concentrations, but underestimated high level values. The annual estimated LRTCion contribution decreased from 7 ± 2 μg/m3 for 1986–2000 to 5 ± 1 μg/m3 for 2001–2010. The higher LRTCion contribution was related to the transport cluster from eastern Europe, UK/North Sea/Denmark and the vicinity of South Scandinavia.

Effects of Local and Saharan Particles on Cardiovascular Disease Mortality

To the Editor: Recent studies suggest that outbreaks of Saharan dust over southern European populations may be harmful, after comparing exposure to particulate matter (PM) fractions during Saharan and non-Saharan dust days. Studies conducted in Barcelona1,2 and Rome3 found that the effects of short-term exposure to coarse fraction during dust days were associated with increased total mortality and, more specifically, cardiovascular mortality. However, the specific contribution of Saharan dust versus other local dust remains to be clarified. If Saharan dust is indeed a risk agent, there is a need to develop a source-specific risk function to guide European legislation on setting standards and acceptable risks. In this study, we estimated the association between daily cardiovascular mortality and PM <10 μm in aerodynamic diameter (PM10) differentiating the effects from Saharan dust and other human-made particulates, during Saharan dust days, in the city of Barcelona between 2003 and 2007. Identification of Saharan dust days was done as in our previous studies.1,2 Additionally, daily PM10 Saharan contributions versus local contributions were calculated from data collected at a regional background site, using a monthly moving 40th percentile to the PM10 time-series after omitting all days with Saharan air mass influence.4 These values were subtracted from the measured daily PM10 concentrations at the regional background site to obtain the amount of African dust brought on any given day under Saharan air-mass influence.4 Finally, the calculated daily African dust was used to distinguish between the urban background PM10 data in Barcelona and daily PM10 Saharan and non-Saharan contributions. We explored the association between daily cardiovascular mortality and PM10 using a time-stratified case-crossover design.5 We used Poisson regression adjusting for temperature, humidity, public holidays, and influenza epidemics, as well as for the 3-way interaction between day of the week, month, and year, to control for seasonality and time trends. This was done to replicate the adjustment made by the case-crossover design with the time-stratified approach for the selection of control days.6 Applying this source apportionment method, 50% of PM10 concentrations on Saharan dust days were due to human-made or local sources (Table). During non-Saharan dust days, the percentage increase of risk (%IR) per 10 μg/m3 at lag 1 due to PM10 was 2.8 (95% confidence interval = 1.6 to 4.1). During Saharan dust days, we found larger estimates, for this same lag, from PM10 attributed to the Saharan contributions (4.0 [−0.4 to 8.7]) and to the local contributions (9.7 [4.3% to 15.3%]) than on non-Saharan dust days.Table: Levels of PM10 and Percentage Increase in Risk of Cardiovascular Mortality 10 μg/m3 During Non-Saharan Dust Days (Contributing Total PM10 Levels) and Saharan Dust Days (Contributing Local and Saharan Contributions to PM10 Levels)Using a novel method to differentiate the Saharan dust contribution from our daily total PM10, our results confirm the role of Saharan dust in triggering negative short-term cardiovascular effects. Intriguingly, however, our results also suggest that human-made particulates on those days have stronger effects than on other days, and that the effects observed in past studies may be driven mostly by the increase in effects of these specific contributions. We have no way of knowing the distribution of particle size of the local distribution, and therefore, we cannot determine whether this increase in effects is driven by the very fine traffic-related particles. However, it may be possible that the local particles become more toxic on Saharan dust days. Saharan dust contains Ca-Mg carbonates and other components that may react with pollutant gases (such as SOx or NOx), thus forming new particles.7 Similarly, there could be chemical reactions with other gases or additional condensation of organic compounds on the particles, enhancing toxicity. While the toxicity of particles remains to be understood, these results reinforce the need to re-evaluate the current exemption during Saharan dust days that the European Union has legislated, because this allows for tolerating an average higher exposure to PMs in population, on the specific days when there are increased effects of both local and exogenous particles. Laura Pérez Swiss Tropical and Public Health Institute University of Basel Basel, Switzerland Aurelio Tobías Jorge Pey Noemí Pérez Andrés Alastuey Institute of Environmental Assessment and Water Research (IDAEA) Spanish Council for Scientific Research (CSIC) Barcelona, Spain [email protected] Jordi Sunyer Centre for Research in Environmental Epidemiology (CREAL) Barcelona, Spain Xavier Querol Institute of Environmental Assessment and Water Research (IDAEA) Spanish Council for Scientific Research (CSIC) Barcelona, Spain.

Ambient particulate pollution and the world-wide prevalence of asthma, rhinoconjunctivitis and eczema in children: Phase One of the International Study of Asthma and Allergies in Childhood (ISAAC)

ObjectivesTo investigate the effect of ambient particulate matter on variation in childhood prevalence of asthma, rhinoconjunctivitis and eczema.MethodsPrevalences of asthma, rhinoconjunctivitis and eczema obtained in Phase One of the International...

Spatial &amp; temporal variations of PM10 and particle number concentrations in urban air

The size of particles in urban air varies over four orders of magnitude (from 0.001 microm to 10 microm in diameter). In many cities only particle mass concentrations (PM10, i.e. particles <10 microm diameter) is measured. In this paper we analyze how differences in emissions, background concentrations and meteorology affect the temporal and spatial distribution of PM10 and total particle number concentrations (PNC) based on measurements and dispersion modeling in Stockholm, Sweden. PNC at densely trafficked kerbside locations are dominated by ultrafine particles (<0.1 microm diameter) due to vehicle exhaust emissions as verified by high correlation with NOx. But PNC contribute only marginally to PM10, due to the small size of exhaust particles. Instead wear of the road surface is an important factor for the highest PM10 concentrations observed. In Stockholm, road wear increases drastically due to the use of studded tires and traction sand on streets during winter; up to 90% of the locally emitted PM10 may be due to road abrasion. PM10 emissions and concentrations, but not PNC, at kerbside are controlled by road moisture. Annual mean urban background PM10 levels are relatively uniformly distributed over the city, due to the importance of long range transport. For PNC local sources often dominate the concentrations resulting in large temporal and spatial gradients in the concentrations. Despite these differences in the origin of PM10 and PNC, the spatial gradients of annual mean concentrations due to local sources are of equal magnitude due to the common source, namely traffic. Thus, people in different areas experiencing a factor of 2 different annual PM10 exposure due to local sources will also experience a factor of 2 different exposure in terms of PNC. This implies that health impact studies based solely on spatial differences in annual exposure to PM10 may not separate differences in health effects due to ultrafine and coarse particles. On the other hand, health effect assessments based on time series exposure analysis of PM10 and PNC, should be able to observe differences in health effects of ultrafine particles versus coarse particles.

Total and water-soluble trace metal content of urban background PM10, PM2.5 and black smoke in Edinburgh, UK

Toxicological studies have implicated trace metals in airborne particles as possible contributors to respiratory and/or cardiovascular inflammation. As part of an epidemiological study, co-located 24 h samples of PM10, PM2.5 and black smoke (BS) were collected for 1 year at an urban background site in Edinburgh, and each sample sequentially extracted with ultra-pure water, then concentrated HNO3/HCl, and analysed for Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd and Pb. This yields a comprehensive data set for UK urban airborne trace metal. The median (n>349) daily water-soluble metal concentration in PM2.5 ranged from 0.05 ng m−3 for Ti to 5.1 ng m−3 for Pb; and in PM10 from 0.18 ng m−3 for Ti to 11.7 ng m−3 for Fe. Median daily total (i.e. water+acid-extractable) metal concentration in PM2.5 ranged from 0.3 ng m−3 for As to 27.6 ng m−3 for Fe; and in PM10 from 0.37 ng m−3 for As to 183 ng m−3 for Fe. The PM2.5:PM10 ratio varied considerably with metal, from <17%, on average, for Ti and Fe, to >70% for V, As, Cd and Pb. The 11 trace metals constituted proportionally more of the PM10–2.5 fraction than of the PM2.5 fraction (0.9%). The proportion of water-soluble metal in each size-fraction varied considerably, from <10% water-soluble Fe and Ti in PM10−2.5, to >50% water-soluble V, Zn, As and Cd in PM2.5. Although Fe generally dominated the trace metal, water-soluble metal also contained significant Zn, Pb and Cu, and for all size and solubility fractions >90% of trace metal was comprised of Fe, Zn, Pb and Cu. Statistical analyses suggested three main sources: traffic; static combustion; and crustal. The association of metals with traffic (Cu, Fe, Mn, Pb, Zn) was consistent with traffic-induced non-exhaust “resuspension” rather than direct exhaust emission. Meteorology contributed to the wide variation in daily trace metal concentration. The proportion of trace metal in particles varied significantly with the air mass source and was highest on days for trajectories traversing over land. For Mn, Fe, Cu, Zn, As and Pb there was greater correlation of metal concentration with BS mass than with either PM10 or PM2.5 mass, suggesting that BS reflectance monitoring could be a cost-effective surrogate measure of particle metal concentration in urban background air.

HEALTH IMPACT ASSESSMENT OF LONG TERM EXPOSURE TO FINE PARTICLES IN FRENCH CITIES

ISEE-567 Abstract: In the framework of the preparation of the National Environment Health Action Plan, a health impact assessment study was conducted in a large number of French metropolitan areas, following the rationale proposed by Künzli et al [2000]. Based on the latest international epidemiological evidence [Pope et al 2002] the number of air pollution attributable cases (lung cancer and cardiopulmonary mortality) was derived, with fine particles as single indicator of urban air pollution. Retrospective urban background PM10 concentration data were retrieved from the Ambient Air Quality National Database covering 76 Urban Units and 15 259 590 adults 30 years old and over. PM10 data were converted into PM2.5 estimates applying a 60 % PM2.5/PM10 ratio. Attributable number of deaths and potentially avoidable cases were computed for year 2002, assuming a 15 year retrospective exposure. The “no risk” baseline exposure level was ranging from 4.5μg/m3 to 9μg/m3, while the average 2002 urban background PM2.5 concentration was 12μg/m3. A set of scenarios was used to forecast ambient air concentrations over the next 20 years. The main results for lung cancer mortality, based on the lowest baseline exposure level (4.5μg/m3), are the following: In 2002, the estimated attributable number of deaths due to the previous 16 years of exposure is 670 [89-1 257]CI95%, which corresponds to an attributable fraction of 6 %. When the target for PM2.5 in year 2020 is set at 4.5μg/m3 (in the “volunteer” scenario), the estimated number of lung cancer attributable cases is 575 [76-1 084] in 2010 and 335 [43-644] in 2020. Under the assumption of a linear reduction of the annual impacts between 2002, 2010 and 2020, the potentially avoidable total number of attributable deaths until 2020 (by comparison with a situation “leave it as it is in 2002”) is 2 698. Results are also available for cardio-pulmonary mortality (figures are about 5 fold greater). A sensitivity analysis was carried out for different exposure reference levels, ambient air quality objectives and RR estimates exposed in the paper by Pope et al. Sources of uncertainty are discussed along with the impact assessment process. Results are put into perspective with a parallel output proposing some action scenarios to reduce urban air pollution levels, and associated exposures.

Some ideas about the sources of PM10

In Berlin, about 50% of the urban background PM10 concentration is due to long range transport—mainly secondary aerosols (ammonium nitrate and ammonium sulphate) and natural sources. At kerbside sites on main streets the PM10-concentration is up to 40% higher than the urban background. Half of this additional pollution is due to motor vehicle exhaust emission and tyre abrasion and the other half is due to resuspended soil particles. On the basis of comparison of the main chemical components at stations in the regional and urban background and a station at the kerbside of a busy street, we estimate the source apportionment for the main source groups. Possible reduction measures are discussed.