| 1. |
- Molnár, Peter, 1967, et al.
(författare)
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Roadside measurements of fine and ultrafine particles at a major road north of Gothenburg
- 2002
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Ingår i: Atmospheric Environment. - 1352-2310 .- 1873-2844. ; 36:25, s. 4115-4123
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Tidskriftsartikel (refereegranskat)abstract
- Particle measurements were conducted at a road site 15 km north of the city of Gothenburg for 3 weeks in June 2000. The size distribution between 10 and 368 nm was measured continuously by using a differential mobility particle sizer (DMPS) system. PM2.5 was sampled on a daily basis with subsequent elemental analysis using EDXRF-spectroscopy. The road is a straight four-lane road with a speed limit of 90 kph. The road passing the site is flat with no elevations where the vehicles run on a steady workload and with constant speed. The traffic intensity is about 20,000 cars per workday and 13,000 vehicles per day during weekends. The diesel fuel used in Sweden is low in sulphur content (< 10 ppm) and therefore the diesel vehicles passing the site contribute less to particle emissions in comparison with other studies. A correlation between PM2.5 and accumulation mode particles (100-368 nm) was observed. However, no significant correlation was found between number concentrations of ultrafine particles (10-100 nm) and PM2.5 or the accumulation mode number concentration. The particle distribution between 10 and 368 nm showed great dependency on wind speed and wind direction, where the wind speed was the dominant factor for ultrafine (10-100nm) particle concentrations. The difference in traffic intensity between workday and weekend together with wind data made it possible to single out the traffic contribution to particle emissions and measure the size distribution. The results presented in combination with previous studies show that both PM2.5 and the mass of accumulation mode particles are bad estimates for ultrafine particles. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 2. |
- Janhäll, Sara, 1965, et al.
(författare)
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Size resolved traffic emission factors of submicrometer particles
- 2004
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 38:26, s. 4331-4340
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Tidskriftsartikel (refereegranskat)abstract
- Size resolved emission factors for submicrometer particles related to trace gases have been obtained from measurement data at a suburban road side, with a traffic intensity of 18,000 vehicles per day. Number of particles with diameter 10-368 nm, trace gases (NO, NOx, O-3 and SO2) traffic and meteorology parameters were measured outside of Goteborg, Sweden. Size distributions of small particles at the site are presented and their relation to meteorological and traffic related variables was evaluated. Wind speed correlated negatively with 10-368 nm particles and temperature correlated negatively with the smaller particles (10-60 nm). Nitric oxide was shown to be a better tracer for traffic related ultrafine particles, than traffic intensity itself. The calculated emission factor, with errors at 95% confidence level, for particles in the range 10-368 nm is presented in relation to nitrogen oxides. The emission factors were 268+/-60 and 176+/-37 particles cm(-3) per ppb NO and NOx, respectively. The particle emission factors for 10-100, 10-50, 50-170 and 170-368 nm were 260+/-70, 228+/-52, 41+/-11 and <1 particle cm(-3) per ppb NO, respectively. The size distribution of the emissions is given by number of particles normalised by the width of the size bin, i.e. in units of dNd log Dp(-1) ppb(-1). The maximum normalised emission factor was 450 cm(-3) per ppb NO for 20 nm particles. The shape of the size distribution of emissions revealed one sharp peak at 20 nm, with a small shoulder at 70 nm. (C) 2004 Elsevier Ltd. All rights reserved.
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| 3. |
- Janhäll, Sara, 1965, et al.
(författare)
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Vertical distribution of air pollutants at the Gustavii Cathedral in Goteborg, Sweden
- 2003
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Ingår i: Atmospheric Environment. - 1352-2310. ; 37:2, s. 209-217
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Tidskriftsartikel (refereegranskat)abstract
- Atmospheric trace gases and particles were measured at two heights at the Gustavii Cathedral in Goteborg, Sweden, during 7 weeks in September and October 1999. The Gustavii Cathedral is situated in the city centre of Goteborg, which is near the harbour area and encircled by heavy traffic some hundred metres away. The main body of the church is as high as the surrounding buildings, while the tower extends well above. The sampling points were placed on the west wall of the tower at 10 and 32 m height, i.e. well below and above the roof top level of surrounding buildings, respectively. Sulphur dioxide and nitric acid were sampled using the denuder technique and analysed by Ion Chromatography, IC. Total suspended particulates (TSP) were sampled using filter cups and subsequently analysed by energy dispersive X-ray fluorescence spectroscopy (EDXRF). In addition to the diurnal sampling of species, nitrogen oxides were measured using chemiluminescence detectors. Additional data from the Environmental Office in Goteborg was used in the analysis. Differences between the concentrations measured at the upper and lower levels were calculated and their variation and dependence on meteorological factors were evaluated. On the average larger concentrations were found at the lower level for soil derived elements and TSP, while nitric acid and nitric oxide showed larger concentrations at the upper level. Sulphur dioxide and nitrogen dioxide, as well as many of the elements in the TSP, showed equal concentrations at the two levels. However, depending on wind direction the measured differences of nitrogen oxides could be both positive and negative. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 4. |
- Molnár, Peter, 1967, et al.
(författare)
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Domestic wood burning and PM2.5 trace elements: Personal exposures, indoor and outdoor levels
- 2005
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 39:14, s. 2643-2653
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Tidskriftsartikel (refereegranskat)abstract
- Personal exposures as well as indoor and outdoor levels of PM2.5 were measured with cyclones and impactors simultaneously in the winter of 2003 in a residential area where wood burning for domestic space heating is common. Twenty-four-hour samples from both wood-burning households ("wood burners") and a reference group were analysed for mass and elemental concentration using energy dispersive X-ray fluorescence (EDXRF) and for black smoke (BS) concentration using an EEL 43 reflectometer. Wood-smoke particles made statistically significant contributions of K, Ca, and Zn for both personal exposure and indoor concentration, the median levels of these elements being 66-80% higher for the wood-burning group. In addition, Cl, Mn, Cu, Rb, and Pb were found to be possible markers of wood smoke, though levels of these were only significantly higher among the wood-burning group for either personal exposure or indoor concentrations. PM2.5 mass and S levels were not significantly elevated in wood burners, probably due to large variations in outdoor concentrations from long-distance transported air pollution. Personal exposure and indoor levels showed high correlations for all species, and the personal exposure levels were usually higher than or equal to the indoor levels. The associations between personal exposure and outdoor levels were generally weak except for outdoor S and PM2.5 levels that were both highly correlated with personal S exposure levels (r(s) > 0.8). (c) 2005 Elsevier Ltd. All rights reserved.
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| 5. |
- Molnár, Peter, 1967, et al.
(författare)
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Residential NOx exposure in a 35-year cohort study. Changes of exposure, and comparison with back extrapolation for historical exposure assessment
- 2015
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 115, s. 62-69
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Tidskriftsartikel (refereegranskat)abstract
- In this study we aimed to investigate the effects on historical NOx estimates on time trends, spatial distributions, exposure contrasts, the effect of relocation patterns and the effects of back extrapolation. Historical levels of nitrogen oxides (NOx) from 1975 to 2009 were modeled with high resolution in Gothenburg, Sweden, using historical emission databases and Gaussian models. Yearly historical addresses were collected and geocoded from a population-based cohort of Swedish men from 1973 to 2007, with a total of 160,568 address years. Of these addresses, 146,675 (91%) were within our modeled area and assigned a NOx level. NOx levels decreased substantially from a maximum median level of 43.9μg/m3 in 1983 to 16.6μg/m3 in 2007, mainly due to lower emissions per vehicle km. There was a considerable variability in concentrations within the cohort, with a ratio of 3.5 between the means in the highest and lowest quartile. About 50% of the participants changed residential address during the study, but the mean NOx exposure was not affected. About half of these moves resulted in a positive or negative change in NOx exposure of >10μg/m3, and thus changed the exposure substantially. Back extrapolation of NOx levels using the time trend of a background monitoring station worked well for 5-7 years back in time, but extrapolation more than ten years back in time resulted in substantial scattering compared to the "true" dispersion models for the corresponding years. These findings are important to take into account since accurate exposure estimates are essential in long term epidemiological studies of health effects of air pollution.
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| 6. |
- Tang, L., et al.
(författare)
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Estimation of the long-range transport contribution from secondary inorganic components to urban background PM10 concentrations in south-western Sweden during 1986-2010
- 2014
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 89, s. 93-101
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Tidskriftsartikel (refereegranskat)abstract
- 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 (C-ion) 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 C-ion 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 C-ion concentrations observed in Gothenburg. For each pathway, multiple linear models based on the C-ion concentrations were used to estimate LRTCion and PM10 at the urban background site. The performances of the multiple linear models were satisfying with R-2 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 mu g/m(3) for 1986-2000 to 5 +/- 1 mu g/m(3) 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. (C) 2014 Elsevier Ltd. All rights reserved.
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