No abstract

The results indicate that relatively low levels of wood smoke exposure induce effects on airways. Effects on airway epithelial permeability was shown for the start-up phase of wood burning, while FENO increased after the burn-out session. CC16 seems to be a sensitive marker of effects of air pollution both in serum and urine, but its function and the significance need to be clarified.

Personal exposure to PM 2.5 and PM 1 , together with indoor and residential outdoor levels, was measured in the general adult population (30 subjects, 23-51 years of age) of Gothenburg, Sweden. Simultaneously, urban background concentrations of PM 2.5 were monitored with an EPA WINS impactor. The 24-h samples were gravimetrically analyzed for mass concentration and black smoke (BS) using a smokestain reflectometer. Median levels of PM 2.5 were 8.4 mg/m 3 (personal), 8.6 mg/m 3 (indoor), 6.4 mg/m 3 (residential outdoor), and 5.6 mg/m 3 (urban background). Personal exposure to PM 1 was 5.4 mg/m 3 , while PM 1 indoor and outdoor levels were 6.2 and 5.2 mg/m 3 , respectively. In non-smokers, personal exposure to PM 2.5 was significantly higher than were residential outdoor levels. BS absorption coefficients were fairly similar for all microenvironments (0.4-0.5 10 À5 m À1 ). Personal exposure to particulate matter (PM) and BS was well correlated with indoor levels, and there was an acceptable agreement between personal exposure and urban background concentrations for PM 2.5 and BS 2.5 (r s ¼ 0.61 and 0.65, respectively). PM 1 made up a considerable amount (70-80%) of PM 2.5 in all microenvironments. Levels of BS were higher outdoors than indoors and higher during the fall compared with spring. The correlations between particle mass and BS for both PM 2.5 vs. BS 2.5 and PM 1 versus BS 1 were weak for all microenvironments including personal exposure. The urban background station provided a good estimate of residential outdoor levels of PM 2.5 and BS 2.5 within the city (r s ¼ 0.90 and 0.77, respectively). Outdoor levels were considerably affected by long-range transported air pollution, which was not found for personal exposure or indoor levels. The within-individual (day-today) variability dominated for personal exposure to both PM 2.5 and BS 2.5 in non-smokers. IntroductionEpidemiological studies have shown associations between exposure to fine particles and health effects, such as increased mortality, cardiovascular diseases, and respiratory illness (Samet et al., 2000;Pope et al., 2002;Brunekreef and Holgate, 2002). In terms of the overall health burden, a significant reduction in the life expectancy of the average population has been linked to long-term exposure to high levels of particulate air pollution. A systematic review by the World Health Organization (WHO) has confirmed that longterm effects of exposure to particulate matter (PM) outweigh short-term effects when it comes to matters of public health significance, and should consequently be the main concern; however, acute effects are also considerable (World Health Organization, 2004). The risk of various health effects following exposure to PM has been shown to increase with exposure, and there is today no evidence of a threshold level regarding the relation between exposure and health outcomes (World Health Organization, 2005). The air quality guidelines for PM 2.5 suggested by the WHO expert group are 10 mg/m 3 as an annual mean and 25 mg/m 3 as a 2...

The general population is exposed to particulate air pollution from many different local and regional sources. Examples of local sources are traffic, biomass burning and resuspended dust, while regional sources are dominated by combustion processes from heating, traffic and industries. The overall aim of this thesis was to characterise the personal exposure to trace elements in fine particles, mainly PM 2.5 and investigate how the exposure is related to indoor and outdoor levels. Particulate matter was collected on filters and analysed for elemental content by X-ray fluorescence (XRF) spectroscopy.In the general population in Göteborg, personal exposures to Cl, Ca, Ti and Fe were significantly higher compared with indoor, residential outdoor and urban background levels. Significant correlations were also found between urban background PM mass and personal exposure to elements related to both combustion (S, V and Pb) and resuspended dust (Ti, Fe and Zn), indicating that both sources could be relevant for health effects from urban background PM. In a community where wood burning for domestic heating is common, significantly (66-80%) higher personal exposures and indoor levels were found for K, Ca and Zn compared with a reference group living in the same area, indicating that these elements could be good markers for wood smoke. In a study in Stockholm concerning children's environments (home, school and preschool), higher indoor than outdoor levels of Ti were found, while long-range-transported (LRT) elements (S, Ni, Br and Pb) were higher outdoors. A community located 25 km from the city centre had significantly lower outdoor levels of crustal and traffic-related elements compared with both the city centre and a suburban area. The levels of Fe and Cu were four times higher in the central communities. Outdoors, Cu levels were found to correlate well with the traffic marker NO 2 , making it a possible elemental marker for traffic-related aerosols in health studies. Roadside measurements of fine and ultrafine (<100 nm) particles were performed along a major approach road to Göteborg and the levels of ultrafine particles were influenced not only by traffic intensity, but also, by wind speed and direction, as well as boundary layer height. No correlation was found between PM 2.5 and ultrafine particles or traffic, but there was a correlation between PM 2.5 and particles sized 100-368 nm. In all environments studied, the origin of LRT air masses had a strong effect on exposure and levels of PM elements.In conclusion, this thesis demonstrates that elemental analysis is a useful method for better characterising human exposure to fine particles. For several elements, the personal exposure is often higher than corresponding indoor levels. The origin of LRT elements affected not only outdoor levels, but also, the personal exposure and indoor levels, and should be taken into account in time series studies of air pollution and health.

Experimental studies are used to evaluate effects of human exposure to diesel exhaust and concentrated ambient particles. This article describes a system for studying exposure of humans to wood smoke. Wood smoke was generated using a wood stove placed outside an exposure chamber that can hold at least 10 subjects. A partial flow of the generated wood smoke from the stove was mixed with filtered indoor air. Personal and stationary measurements were performed of PM2.5 and PM1 mass concentrations and various volatile organic compounds (VOCs): 1,3-butadiene, benzene, and aldehydes. In addition, particulate matter (PM) mass, number concentrations, and size distributions of particles (0.007-6.7 microm), as well as nitrous oxides, CO2, and CO, were measured online. Filters were analyzed for trace elements and black smoke. Polycyclic aromatic compounds, toluene, and xylenes were determined in stationary samples. Results of the first experiment showed no differences between personal and stationary measurements for particles or VOCs. Consequently, stationary measurements can be used to predict personal exposure. All PM mass (about 250 microg/m3) was in the PM1 fraction. Subjective symptoms were generally weak, while clear objective signs were found, for example, in biomarkers of inflammation. With careful control of the combustion process, relatively constant mass and number concentrations were obtained over each exposure session. By varying the combustion and dilution of the wood smoke, different exposure scenarios can be achieved and thus, knowledge about which of the properties of particles and gaseous compounds are crucial for the effects.

Background Short-term controlled exposure to diesel exhaust (DE) in chamber studies have shown mixed results on lung and systemic effects. There is a paucity of studies on well-characterized real-life DE exposure in humans. In the present study, 29 healthy volunteers were exposed to DE while sitting as passengers in diesel-powered trains. Exposure in electric trains was used as control scenario. Each train scenario consisted of three consecutive days (6 h/day) ending with biomarker samplings. Results Combustion-derived air pollutants were considerably higher in the passenger carriages of diesel trains compared with electric trains. The concentrations of black carbon and ultrafine particles were 8.5 μg/m 3 and 1.2–1.8 × 10 5 particles/cm 3 higher, respectively, in diesel as compared to electric trains. Net increases of NOx and NO 2 concentrations were 317 μg/m 3 and 36 μg/m 3 . Exposure to DE was associated with reduced lung function and increased levels of DNA strand breaks in peripheral blood mononuclear cells (PBMCs), whereas there were unaltered levels of oxidatively damaged DNA, soluble cell adhesion molecules, acute phase proteins in blood and urinary excretion of metabolites of polycyclic aromatic hydrocarbons. Also the microvascular function was unaltered. An increase in the low frequency of heart rate variability measures was observed, whereas time-domain measures were unaltered. Conclusion Exposure to DE inside diesel-powered trains for 3 days was associated with reduced lung function and systemic effects in terms of altered heart rate variability and increased levels of DNA strand breaks in PBMCs compared with electric trains. Trial registration ClinicalTrials.Gov ( NCT03104387 ). Registered on March 23rd 2017

Diesel-powered trains are used worldwide for passenger transport. The present study aimed to assess air pollution concentrations in passenger cars from diesel and electric trains. Personal exposure monitoring (6-7 hours per day) was carried out for 49 days on diesel and 22 days on electric trains. Diesel trains had higher concentrations of all the assessed air pollution components. Average increases (and fold differences) in passenger cars of diesel trains compared with electric trains were for ultrafine particles 212,000 particles/cm 3 (35-fold), black carbon 8.3 µg/m 3 (6-fold), NO X 316 µg/m 3 (8-fold), NO 2 38 µg/m 3 (3-fold), PM 2.5 34 µg/m 3 (2-fold) and benzo(a)pyrene 0.14 ng/m 3 (6-fold). From time-series data, the pull and push movement modes, the engine in use and the distance to the locomotive influenced the concentrations inside the diesel trains. In conclusion, concentrations of all air pollutants were significantly elevated in passenger cars in diesel trains compared to electric trains.

Mixed-effects models were used to estimate within-person and between-person variance components, and some determinants of environmental exposure to particulate matter (PM 2.5 ), black smoke (BS) and trace elements (Cl, K, Ca, Ti, Fe, Ni, Cu, Zn, and Pb) for personal measurements from 30 adult subjects in Gothenburg, Sweden. The within-person variance component dominated the total variability for all investigated compounds except for PM 2.5 and Zn (in which the variance components were about equal). Expressed as fold ranges containing 95% of the underlying distributions, the within-person variance component ranged between 5-fold and 39-fold (median: sixfold), whereas the between-person variance component was always osixfold (median: threefold). The relatively large within-person variance components can lead to attenuation bias in exposure-response relationships and point to the importance of obtaining repeated samples of PM exposure from study subjects in epidemiological investigations of urban air pollution. On the basis of the variance components estimated for the various particulate species, between 3 and 39 repeated measurements per subject would be required to limit attenuation bias to 20%. Significant determinants for personal exposure levels were urban background air concentrations (PM 2.5 , BS, Cl, Zn, and Pb), cigarette smoking (PM 2.5 , BS, K, and Ti), season (PM 2.5 , Fe, and Pb), and the time spent outdoors or in traffic (Fe).