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The indoor and outdoor concentrations of particulate air-pollution and PAHs in different size fractions and assessment of exposure and health impacts in the Copenhagen population 2 Experimental methods
2.1 Sampling conditionsOne-week samples of PM1, PM2.5, PMinh (inhalable dust) and PAH's were collected from three locations at two fieLD sites (Fig. 2.1): Indoors and immediately outside the living room window of a 4th floor uninhabited apartment at Jagtvej, 2200 Nørrebro, Copenhagen, Denmark and at the 4th floor-high roof-top of the National Institute of Occupational Health (NIOH), Lersø Parkallé, DK-2100 Copenhagen, Denmark. Figure 2.1: Map showing the location of the fieLD sites in the study and placement of city train tracks and crematories, which are potential local particle and/or PAH near the fieLD sites. All samples were collected during three fieLD campaigns in 2002 covering winter (Jan 9 – Febr 13), spring (March 27 – May 8) and early summer (May 29 – June 26). The first two fieLD campaigns were conducted contemporaneously with the last two multi-instrumental fieLD campaigns in the national research project called TRIP (http://www.akf.dk/trip/index.htm). It was not possible to obtain samples during fall as the sublet contract of the apartment ended June 2002. 2.2 Description of fieLD sites2.2.1 The Jagtvej apartment (Jagtvej_IN)Indoor particulate and PAH air-pollution were sampled in a furnished uninhabited 35.3 net m2 apartment. The apartment was located at the fourth floor (3. sal, tv.) in a residential Building at Jagtvej 83, in the central part of Copenhagen, Denmark (Fig. 2.1).
Figure 2.1: a) Picture of the apartment façade at Jagtvej. The encircled living-room window indicates the apartment used for the study. b) Image of the PM samplers mounted 1.5 m above the floor in the living-room, ~1.5 m from the living-room window. The CIS sampler is seen in the middle between the two Triplex cyclones for collection of PM1 and PM2.5. Tenax tubes are mounted in line after the PM2.5 sampler on the right hand side. The Building was erected around 1900 and has five stories with dwellings. The basement contains shops and storage rooms. The outer walls were masonry and ~32 cm thick story-partitions were made of wood with a layer of clay in between floor planks and underlying basal floor planks. In 1984 the Building was renovated with mechanical exhaust-only ventilation connected to kitchens and bathrooms. The centralized heating system connected to municipality district heating is from the same period. Heating was maintained using radiators with thermostats placed under the windows. New double glazed windows had been installed in well-sealed new frames around 1995. During the fieLD campaigns, the apartment and mechanical ventilation was modified by inserting a false door, sealing of the kitchen area, where all pumps and computer equipment were stored (Fig. 2.2). Tubes and wires were led through drilled and sealed holes in the false door structure. Taping door-cracks, keyholes and the mail slit in the entrance hall with gaffa tape minimized ventilation through the entrance door to the hallway. Owing to the construction type with wooden floors and the recent replacement of pipes for the central heating system, story-partitions could not be expected to be airtight. The new windows, on the hand other were very airtight. Therefore ventilation slits were inserted in the street-ward window to allow higher fresh-air ventilation rates to levels closer to of at least 0.5 h1 satisfying the Danish Building regulations. Despite this modification, results from the TRIP-project suggest that a significant amount of replacement air may enter the studied apartment through neighboring dwellings. Less than 20% of the replacement air entered directly from the street through the designated ventilation slits). Therefore, there is a high risk of contamination of especially volatile compounds from neighbour activities.
Figure 2.2: Sketch of the Jagtvej apartment with location of the indoor and outdoor sampling locations. The kitchen was sealed of by inserting an air-tight false door between the hallway and the kitchen. Air-exchange through the front door was sought eliminated by taping of the mail-slit, key-hole and the edges around the door. 2.2.2 The Jagtvej street canyon (Jagtvej_EXT)Outdoor particulate and PAH air-pollution were sampled in the Jagtvej street canyon at 4th floor height immediately outside the living room window of the uninhabited apartment (Fig. 2.2). Jagtvej is a NW-SE oriented two-way street with a traffic load on the order of 26,000 vehicles per working day of which approximately 6 % of the traffic is heavy traffic. In the monitoring area, the street canyon is partially open owing to the presence of a small street perpendicular to Jagtvej and a lower Building opposite of the apartment complex. The samplers were mounted outside the living room window, placed next to each other appr. 10-15 cm apart shielded from direct sunlight at rain by a white hard-plastic bucket. Great care was taken to ensure that the sample inlet was well free of the shelter. There was no apparent risk of sample contamination from proximate outdoor particles or PAH point sources at the 4th floor sampling height. However, at ground level, a bus stop was located on both sides of the street in front of the monitored Building complex. Additionally, the near-by intersection between Jagtvej and Nørreallé (Fig. 2.1), which is another densely trafficked city road in Copenhagen, also may play a role on the local air-pollution levels. At 4th floor height, however, these local effects are thought to be highly diluted and be of negligible importance as compared to the general traffic-load on Jagtvej senso stricto. 2.2.3 The National Institute of Occupational Health, Denmark (NIOH)Urban background particulate and PAH air-pollution were sampled at the 4th floor roof-top height of the National Institute of Occupational Health (NIOH) lecture hall (Fig. 2.3). The NIOH is located at the NW-SE oriented Lersø Parkallé 105, DK-2100 Copenhagen (Fig. 2.1).
Figure 2.3: Photo of the National Institute of Occupational Health, Denmark showing where the roof-top was selected for urban background measurements. The samplers were placed at the arrow. The NIOH Buildings are placed in a relatively open-Build area of Copenhagen dominated by two-to-three story office-Buildings and a park to the E and SE. The lecture hall, where measurements were conducted, lays withdrawn from the Lersø Parkallé with no taller Buildings around it. Towards the E, behind the NIOH Buildings, an open area also occurs through which a electrically driven city-trains pass twelve times per hour from 5 am to 7 pm and six times per hour from 7 pm to 1 am and on Sundays (Fig. 2.1). On the lecture hall rooftop, the samplers were located approximately 5 m's from the inlet of an encased rooftop ventilation system (Fig. 2.3). The samplers were mounted next to each other app. 10-15 cm apart 1.5 m above the rooftop shielded from direct sunlight at rain by a white hard-plastic bucket, similar to that at Jagtvej street canyon (section 2.2.1). The location of the samplers was chosen to minimize the potential contamination from the exhaust duct, placed on the opposite site of the encasement. However, during SE wind directions, the ventilation shed may to a minor extent act as a shield. SE-winds mainly occurred during the spring and summer time and varied between 5 and 23% of the time on a weekly basis (http://www.dmi.dk/dmi/index/viden/dmi-publikationer/tekniskerapporter.htm). As the samplers were placed away from exhaust ducts, Building ventilation exhausts were not expected to affect the measurements significantly. No additional point sources to particles and PAH's were identified in the near proximity of the samplers. Further away, two major point sources; a fossil fuel energy plant (Vestforbrænding, Bispebjerg) and the local hospital crematorium (Bispebjerg Crematorium) occur to the E. Meteorological data showed that eastern winds were frequent for the spring (0-36% of the time) and summer campaigns (0-70% of the time). However, owing to the strict environmental legislation for point sources in Denmark and the relatively distant location, we expect the contamination to be short-time episodic and insignificant over the course of a sampling time of one week. 2.3 Indoor and outdoor meteorologyWind direction and wind speed for Great Copenhagen are listed in Appendix A and were obtained from the Danish Meteorological Institute (DMI; http://www.dmi.dk/dmi/index/viden/dmi-publikationer/tekniskerapporter.htm) based on the Copenhagen Airport monitoring station. These data were used to assess potential effects from point sources as discussed in the section above. Indoor air-exchange rates were obtained from the TRIP-project until it ended May 8, 2002. During the TRIP study, the air-exchange rate was fixed at appr. 0.5 and 1 h-1 every alternating week during the measurement campaigns and monitored using three-point trace gas measurements of SF6 . After May 8, 2002, the air-exchange was uncontrolled and not monitored. 2.4 Collection of particulate matter and volatile compounds2.4.1 Collection of PM1, PM2.5 and Inhalable dustParticles and PAH's were collected on GFC glass fibre filters (Millipore AP 4003705) using Triplex cyclones (BGI Inc.) for PM1 and PM2.5 and CIS's (Conical Inhalable Samplers) for inhalable dust (PMinh). See Appendix B for a detailed description of sampling conditions and collection efficiencies of the samplers. Mass-concentrations were determined by weighing using a high-precision Sartorius Micro Scale (Sartorius AG, Göttingen, Germany). Filters were weighed after 24 hours of equilibration in a climate controlled weighing room (20°C; 50% RH) before and after exposure. Each filter series included three un-exposed filters used as internal controls for passive mass changes and chemical analysis of sorbed volatiles in the PAH measurements. Weighing data were also corrected for mass loss during mounting and dismounting filters in the samplers (see Appendix B). Prior to weighing and air-sampling, the GFC filters were cleaned in an EMITECH K1050X plasma asher (Emitech Ltd. Kent, U.K.) operated at 85 W using 15 mL O2 per minute for 15 minutes at an air-pressure of 6 10-1 mbar. This was completed to prevent potential contamination of PAH's on the filters for the subsequent HPLC analysis. After weighing, the filters were stored in a freezer (–20°C) placed in individual glass petri dishes and wrapped in aluminum foil until extraction for chemical analysis of organic compounds. 2.4.2 Collection of volatile compoundsSVOCs in the gas phase, not trapped by the filter, or evaporated from particles on the filter during sampling were collected using cleaned Tenax TA sample and backup tubes (see Appendix D) mounted down stream the PM2.5 filter sampler. The main purpose was to collect volatile PAHs as well as check for the potential break-through of semi-volatile PAHs during sampling. Prior to sampling, the tubes were cleaned by heating up to 275 °C in a stream of nitrogen. The tubes were checked for contamination by thermal desorption and GC with a FID detector. The mass-concentrations of the volatile compounds were calculated based on the total volume flow for the respective PM2.5 samples. 2.5 Analysis of PAHs2.5.1 Pressurized Liquid Extraction of glass fibre filters and Tenax TAPAHs were extracted using a Dionex ASE 200 Accelerated Solvent Extractor for PLE equipped with 1-mL and 5-mL stainless steel extraction cells. PLE is a fully automated extraction process that uses liquid solvents at high temperature (above the boiling point) and pressure (to keep the solvent liquid) for extraction of the sample. The solvent is pumped into the extraction cell containing the sample and after some minutes with high temperature and pressure the extract is transferred from the heated cell to a collection vial. The sample was then ready for analysis. However, solvent volume reduction of glass fibre filter extracts was required. The PLE parameters used for the PAH extraction are shown in Appendix D. 2.5.2 High Performance Liquid Chromatography (HPLC) analysisSixteen PAH compounds were analyzed using HPLC with UV and fluorescence detection (FD) using multiple wavelength shifts for simultaneous quantification of sixteen different PAH compounds . The PAH compounds were separated by reversed-phase HPLC and detected by UV absorbance at 254 nm with a diode array detector (DAD) for quantification of acenaphtylene, fluoranthene and indeno(1,2,3-cd)pyrene and a FD to quantify the other 13 PAH compounds using multiple wavelength shifts. The quality of the PAH analyses was controlled and documented with several different methods. Analytical details and the HPLC parameters used for the PAH analysis are shown in Appendix D.
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