Lars Gidhagen

Model simulation of ultrafine particles inside a road tunnel

A monodispersive aerosol dynamic model, coupled to a 3D hydrodynamical grid model, has been used to study the dynamics of ultrafine particles inside a road tunnel in Stockholm, Sweden. The model results were compared to measured data of particle number concentrations, traffic intensity and tunnel ventilation rate. Coagulation and depositional losses to the tunnel walls were shown to be important processes during traffic peak hours, together contributing to losses of 77% of the particles smaller than 10nm and 41% of the particles of size 10-29nm. Particle growth due to water uptake or the presence of a micron-sized, resuspended particle fraction did not have any significant effect on the number of particles lost due to coagulation. Model simulation of particle number concentration response to temporal variations in traffic flow showed that constant emission factors could be used to reproduce the concentration variations of the particles larger than 29nm, while vehicle-speed-dependent factors are suggested to reproduce the variation of the smallest fractions. The emission factors for particle number concentrations estimated from the model simulation are in general higher and show a larger contribution from light-duty vehicles than what has been reported from a tunnel in California. The model study shows that combined measurements and model simulations in road tunnels can be used to improve the determinations of vehicle emission factors for ultrafine particles under realistic driving conditions

Coastal upwelling in the Baltic Sea—Satellite and in situ measurements of sea-surface temperatures indicating coastal upwelling

Abstract Satellite data (AVHRR) and in situ data of sea-surface temperatures have been used to describe wind-induced upwelling along the Swedish coast of the Baltic. The satellite data, transformed to isotherm charts, points out three sections of the coast where the upwelling is especially intense. The cold upwelled water, normally found within 10–20 km from the coast, sometimes spreads out in finger-like filaments. There are indications of propagation of upwelling fronts and centers, which may be associated with coastal-trapped waves. Ten years of in situ measurements of sea-surface temperature have been used for a statistical compilation of upwelling events. The statistics reveal that upwelling is a common feature along certain sections of the coast, occurring for about one-fourth to one-third of the time. Some information of time scales and temperature anomalies associated with the upwelling events are also given. A wind analysis shows a correlation between upwelling and winds parallel to the shore line, in accordance with the Ekman theory of upwelling generation.

Traffic noise and cardiovascular health in Sweden: The roadside study

Long-term exposure to traffic noise has been suggested to increase the risk of cardiovascular diseases (CVD). However, few studies have been performed in the general population and on railway noise. This study aimed to investigate the cardiovascular effects of living near noisy roads and railways. This cross-sectional study comprised 25,851 men and women, aged 18-80 years, who had resided in Sweden for at least 5 years. All subjects participated in a National Environmental Health Survey, performed in 2007, in which they reported on health, annoyance reactions and environmental factors. Questionnaire data on self-reported doctors diagnosis of hypertension and/or CVD were used as outcomes. Exposure was assessed as Traffic Load (millions of vehicle kilometres per year) within 500 m around each participants residential address. For a sub-population (n = 2498), we also assessed road traffic and railway noise in L(den) at the dwelling façade. Multiple logistic regression models were used to assess Prevalence Odds Ratios (POR) and 95% Confidence Intervals (CI). No statistically significant associations were found between Traffic Load and self-reported hypertension or CVD. In the sub-population, there was no association between road traffic noise and the outcomes; however, an increased risk of CVD was suggested among subjects exposed to railway noise ≥50 dB(A); POR 1.55 (95% CI 1.00-2.40). Neither Traffic Load nor road traffic noise was, in this study, associated with self-reported cardiovascular outcomes. However, there was a borderline-significant association between railway noise and CVD. The lack of association for road traffic may be due to methodological limitations.

Fine and coarse particulate air pollution in relation to respiratory health in Sweden

Health effects have repeatedly been associated with residential levels of air pollution. However, it is difficult to disentangle effects of long-term exposure to locally generated and long-range transported pollutants, as well as to exhaust emissions and wear particles from road traffic. We aimed to investigate effects of exposure to particulate matter fractions on respiratory health in the Swedish adult population, using an integrated assessment of sources at different geographical scales. The study was based on a nationwide environmental health survey performed in 2007, including 25 851 adults aged 18–80 years. Individual exposure to particulate matter at residential addresses was estimated by dispersion modelling of regional, urban and local sources. Associations between different size fractions or source categories and respiratory outcomes were analysed using multiple logistic regression, adjusting for individual and contextual confounding. Exposure to locally generated wear particles showed associations for blocked nose or hay fever, chest tightness or cough, and restricted activity days with odds ratios of 1.5–2 per 10-μg·m−3 increase. Associations were also seen for locally generated combustion particles, which disappeared following adjustment for exposure to wear particles. In conclusion, our data indicate that long-term exposure to locally generated road wear particles increases the risk of respiratory symptoms in adults. Long-term exposure to locally generated road wear particles increases the risk of respiratory symptoms in adults http://ow.ly/nutsB

Long-term effects of total and source-specific particulate air pollution on incident cardiovascular disease in Gothenburg, Sweden

Background and aims Long‐term exposure to air pollution increases cardiopulmonary morbidity and mortality, but it is not clear which components of air pollution are the most harmful, nor which time window of exposure is most relevant. Further studies at low exposure levels have also been called for. We analyzed two Swedish cohorts to investigate the effects of total and source‐specific particulate matter (PM) on incident cardiovascular disease for different time windows of exposure. Methods Two cohorts initially recruited to study predictors of cardiovascular disease (the PPS cohort and the GOT‐MONICA cohort) were followed from 1990 to 2011. We collected data on residential addresses and assigned each individual yearly total and source‐specific PM and Nitrogen Oxides (NOx) exposures based on dispersion models. Using multivariable Cox regression models with time‐dependent exposure, we studied the association between three different time windows (lag 0, lag 1–5, and exposure at study start) of residential PM and NOx exposure, and incidence of ischemic heart disease, stroke, heart failure and atrial fibrillation. Results and discussion During the study period, there were 2266 new‐onset cases of ischemic heart disease, 1391 of stroke, 925 of heart failure and 1712 of atrial fibrillation. The majority of cases were in the PPS cohort, where participants were older. Exposure levels during the study period were moderate (median: 13 &mgr;g/m3 for PM10 and 9 &mgr;g/m3 for PM2.5), and similar in both cohorts. Road traffic and residential heating were the largest local sources of PM air pollution, and long distance transportation the largest PM source in total. In the PPS cohort, there were positive associations between PM in the last five years and both ischemic heart disease (HR: 1.24 [95% CI: 0.98–1.59] per 10 &mgr;g/m3 of PM10, and HR: 1.38 [95% CI: 1.08–1.77] per 5 &mgr;g/m3 of PM2.5) and heart failure. In the GOT‐MONICA cohort, there were positive but generally non‐significant associations between PM and stroke (HR: 1.48 [95% CI: 0.88–2.49] per 10 &mgr;g/m3 of PM10, and HR: 1.50 [95% CI: 0.90–2.51] per 5 &mgr;g/m3 of PM2.5, in the last five years). Effect estimates were stronger for women, non‐smokers, and higher socioeconomic classes. Exposure in the last five years seemed to be more strongly associated with outcomes than other exposure time windows. Associations between source‐specific PM air pollution and outcomes were mixed and generally weak. High correlations between the main pollutants limited the use of multi‐pollutant models. Conclusions The main PM air pollutants were associated with ischemic heart disease and stroke (in women) at the relatively low exposure levels in Gothenburg, Sweden. The associations tended to be stronger for women than for men, for non‐smokers than for smokers, and for higher socioeconomic classes than for lower. The associations could not be attributed to a specific PM source or type, and differed somewhat between the two cohorts. The results of this study confirm that further efforts to reduce air pollution exposure should be undertaken in Sweden to reduce the negative health effects in the general population. HighlightsParticle levels were associated with increased incidence of ischemic heart disease.Particle levels were associated with increased incidence of stroke in women.Associations were stronger in women, non‐smokers, and higher socioeconomic classes.The health effects could not be attributed to a specific PM source or type.

Evaluation of new model tools for meeting the targets of the EU Air Quality Directive: a case study on the studded tyre use in Sweden

Two new model tools have been developed for meeting the EU Air Quality Directive targets: SIMAIRroad (related to traffic emissions) and SIMAIRrwc (rwc standing for residential wood combustion). The models have been evaluated for different traffic situations and for residential areas with wood combustion, with promising results. The models can calculate PM10 statistics, such as mean values and 90 and 98 percentiles, that are well within ±50%. In fact, most of the results are within ±25%. Studded tyres are one important factor causing high PM10 concentrations in Swedish streets, so reducing their use would considerably improve air quality.

Estimates of black carbon and size-resolved particle number emission factors from residential wood burning based on ambient monitoring and model simulations.

Abstract In this paper we derive typical emission factors for coarse particulate matter (PM10), oxides of nitrogen (NOx), black carbon (BC), and number particle size distributions based on a combination of measurements and air quality dispersion modeling. The advantage of this approach is that the emission factors represent integrated emissions from several vehicle types and different types of wood stoves. Normally it is very difficult to estimate the total emissions in cities on the basis of laboratory measurements on single vehicles or stoves because of the large variability in conditions. The measurements were made in Temuco, Chile, between April 18 and June 15, 2005 at two sites. The first one was located in a residential area relatively far from major roads. The second site was located in a busy street in downtown Temuco where wood consumption is low. The measurements support the assumption that the monitoring sites represent the impact of different emission sources, namely traffic and residential wood combustion (RWC). Fitting model results to the available measurements, emission factors were obtained for PM10 (RWC = 2160 ± 100 mg/kg; traffic = 610 ± 51 mg/vehkm), NOx (RWC = 800 ± 100 mg/kg; traffic = 4400 ± 100 mg/veh-km), BC (RWC = 74 ± 6 mg/kg; traffic = 60 ± 3 mg/veh-km) and particle number (N) with size distribution between 25 and 600 nm (N25–600) (RWC = 8.9 ± 1 × 1014 pt/kg; traffic = 6.7 ± 0.5 × 1014 pt/veh-km). The obtained emission factors are comparable to results reported in the literature. The size distribution of the N emission factors for traffic was shown to be different than for RWC. The main difference is that although traffic emissions show a bimodal size distribution with a main mode below 30 nm and a secondary one around 100 nm, RWC emissions show the main mode slightly below 100 nm and a smaller nucleation mode below 50 nm.

High-resolution modeling of residential outdoor particulate levels in Sweden.

Large-scale exposure assessments that include both between- and within-city differences in air pollution levels are lacking. The objective of this study was to model long-term particle exposure for the whole of Sweden, separating long-range transport from local sources, which were further separated into combustion and road dust. Annual regional, urban and local traffic PM exposure contributions were modeled for 26,000 addresses from a national survey, using a European scale model, an urban model and a local traffic model. Total PM10 was overall dominated by the regional contribution, ranging from 3.5 μg/m3 (northernmost) to 13.5 μg/m3 (southernmost). Local traffic and urban sources contributed nationally on average to 16% of total PM10, but for urban populations this contribution was larger (for Stockholm around 30%). Generalized to the Swedish adult population, the average residential exposure contributions from regional, urban and local traffic PM10 were 10.2, 1.3 and 0.2 μg/m3, respectively. Corresponding exposure to PM1 was 5.1, 0.5 and 0.03 μg/m3, respectively. Long-range transport dominates average Swedish residential PM1 and PM10 levels, but for urban populations the contributions from urban and local traffic sources are important and may even dominate for residences close to heavily trafficked roads. The study shows the importance of considering both national and city-scale gradients. The approach to exposure modeling at home addresses of a Swedish cohort includes both the regional scale and the urban and local traffic contributions to total PM exposure. With this we can resolve both between- and within-city gradients in national exposure assessments. The within-city exposure is further divided into a submicron (combustion) and a supermicron (road dust generated by studded tires) part. This gives new possibilities to study health impacts of different particles generated in Scandinavian cities.

A Decision Support System for Urban Climate Change Adaptation

This paper gives an overview of a decision support system for scientists and city planners which shall be suitable to assess climate change effects on urban environments, and which shall enable city planners to investigate different measures to cope with potential effects of climate change. The system named SUDPLAN (Sustainable Urban Development Planner) is currently under development and the first version of the SUDPLAN software will be available when the HICSS conference is held. SUDPLAN is a project funded under the European Framework Program FP7.

Modeling Effects of Climate Change on Air Quality and Population Exposure in Urban Planning Scenarios

We employ a nested system of global and regional climate models, linked to regional and urban air quality chemical transport models utilizing detailed inventories of present and future emissions, to study the relative impact of climate change and changing air pollutant emissions on air quality and population exposure in Stockholm, Sweden. We show that climate change only marginally affects air quality over the 20-year period studied. An exposure assessment reveals that the population of Stockholm can expect considerably lower NO2 exposure in the future, mainly due to reduced local NOx emissions. Ozone exposure will decrease only slightly, due to a combination of increased concentrations in the city centre and decreasing concentrations in the suburban areas. The increase in ozone concentration is a consequence of decreased local NOx emissions, which reduces the titration of the long-range transported ozone. Finally, we evaluate the consequences of a planned road transit project on future air quality in Stockholm. The construction of a very large bypass road (including one of the largest motorway road tunnels in Europe) will only marginally influence total population exposure, this since the improved air quality in the city centre will be complemented by deteriorated air quality in suburban, residential areas.