PCB Emissions Research Articles

Influence of iron ore properties on dioxin emissions during iron ore sintering

Iron ores are principal input materials for iron and steel-making industries. Quality of iron ores is one of the critical parameters for formation of environmental pollutants related to the steel-making process. Dioxins are identified as one of the most toxic pollutants emitted during ironmaking, specifically during the sintering process. This study applied four types of iron ores and analyzed their moisture, density, particle size distribution and element concentrations to investigate their effect on the dioxin formation during sintering. Each type of iron ore was processed in a sinter pot grate. During each processing route, exhausted dust and generated sinter products were collected and subjected to PCDD/F and PCB analysis. Statistical analysis was applied to assess correlations between properties of iron ores and exhausted dioxin emissions, identifying key contributors to dioxin formation during sintering process. Results showed that Fe in iron ores was positively and significantly related to PCB 114 formation in dust and confirmed its co-catalytic effect on dioxin formation. Concentrations of Al, Ti and Cl in iron ores greatly increased PCDD/F and PCB emissions in the sintered products compared to dioxins in dust samples. The S levels and density of iron ores were highly related to the increasing PCDD/F and PCB emissions in both sinter and dust samples. By contrast, concentrations of Si in iron ores played a significant role in decreasing PCDD/F and PCB emissions in both sinter and dust samples. This study also confirmed the optimum size (< 1 mm–2.59 mm) for iron ores, which helps reduce dioxin emissions without affecting the quality of iron and steel-making products.

A Technique to Control the Harmonic Levels in Time-Modulated Antenna Arrays—Theoretical Concept and Hardware Verification Platform

This article presents techniques into prediction and control of the radiated harmonic levels in time-modulated antenna arrays (TMAs). The effect of ramping on the controlling switching waveform, due to slew in the RF switches, is analyzed first. This is followed by a novel technique for controlling and reducing the fundamental carrier component (due to the Fourier series 0 Hz term) that is always produced by TMAs. A new bespoke, steerable, TMA RF hardware test platform is presented, using three gain states to pragmatically implement the proposed carrier reduction technique. The platform implementation utilizes binary logic control interfaces to the TMA, rather than analog control interfaces. Laboratory measurements using the test platform demonstrate a 16.5 dB reduction (limited by PCB emissions) in the level of the fundamental carrier component relative to the steered first harmonic, from a possible reduction of 21.3 dB. The array gain for the first harmonic beam is 2 dBi.

Dioxin-like pcb emissions from cement kilns during the use of alternative fuels

The substitution of combustion fuels in cement plants is increasing throughout many countries, and its individual performance is constantly assessed against strict regulatory standards. For cement plants within Australia, normal operations remain to use petroleum coal as the dominate energy source at the precalciner, avoiding the opportunity to reduce carbon-based resources and pollutant emissions (such as carbon dioxide, oxides of nitrogen, persistent organic pollutants) whilst providing the necessary energy needs through resource recovery. This paper presents stack emission monitoring of health-critical dl-PCB (dioxin-like polychlorinated biphenyl) congeners during the substitution of alternative fuels at ten Australian cement plants, and to distinguish statistical similarities between other key pollutants (such as polychlorinated dibenzo-p-dioxins and furans (PCDD-F) and hydrogen halogens) and amongst the fuels used. Sampling of plant emissions was performed during normal operations (as baseline trials) and with the varied substitution rates of waste oil, solvents, chipped wood, refuge waste, carbon dust, shredded tyres and black sand (as experimental trials).The extraction of field and analytical data during these trials allowed for determining the total and individual unit mass of dl-PCB and PCDD-F isomers, standardised to 10% O2 and to World Health Organization (2005) toxicity equivalence (TEQ) values. The findings showed waste co-incineration during cement operations does reduce health-critical congeners of dioxins and dl-PCBs whilst providing the necessary energy and calcination needs. Experimental trials showed all dl-PCBs and PCB TEQ are below the internationally regulated Stockholm Convention article of 10pg TEQ/Nm3. In several cases, an increased rate of substituted fuel also identified a consistent reduction to baseline dl-PCBs. The distribution of toxic isomers (TCDD-F and PeCDD-F) were shown to be predominate during waste oil, wood chips, and solvent trials. Whereas the use of TDFs consistently showed a lower toxicity contribution. The distribution of dl-PCBs toxic congeners showed PCB-126 (3,3′,4,4′,5-Pentachlorobiphenyl) to be greatly present during the co-incineration of waste oil, wood chips, solvents and TDF trials. Principle component analysis identified a statistical predominance from the 1,2,3,7,8-PeCDF (Pentachlorodibenzofuran) and 1,2,3,4,7,8-HxCDF (Hexachlorodibenzofuran) congeners, while dl-PCBs TEQs had similar correlation amongst combustion fuels with major contributions being from the PCB-126 and PCB-169 (3,3′,4,4′,5,5′-Hexachlorobiphenyl) congeners.

Airborne PCB patterns and urban scale in the Southern Río de la Plata Basin, Argentina

Atmospheric Polychlorinated Biphenyls (PCBs: ∑ 42 congeners) collected by polyurethane passive samplers (PAS-PUFs) in 29 stations from July 2010 to February 2014 (n=141) in the most productive and populated Southern Rio de la Plata area in Argentina were evaluated to assess concentration gradients, potential sources and compositional profiles related to different land use and urbanization. On a global scale, total airborne PCBs concentrations are low/very low (below detection limit to 937pgm−3) and show a significant potential correlation with urban scale increasing 2.5 times each 10 times increase of population reflecting the primary role of urbanization controlling PCB emissions. Compositional patterns evaluated by principal component analysis (PCA) of individual congeners indicated that highly populated atmospheres are enriched in lighter, more volatile tri, tetra and penta chlorine congeners of lighter Aroclor mixtures (from 1242 to 1254) suggesting actual emission of fresh PCBs signatures from sealants, combustion and/or electrical equipment. Sub urban and rural sites show a gradual transition to heavier Aroclor mixtures (from 1254 to 1260) with predominance of more persistent hexa and hepta PCBs indicating an aged background signal resulting from long range transport and/or re-emission from historic reservoirs such as soils.

The Use of Passive Samplers to Reveal Industrial and Agricultural Pollution Trends in Swiss Rivers.

This study shows the efficiency of passive sampling to reveal industrial and agricultural pollution trends. Two practical applications for nonpolar and polar contaminants are presented. Low-density polyethylene (LDPE) samplers were deployed for one year in the Venoge River (VD) to monitor indicator PCBs (iPCBs, IUPAC nos. 28, 52, 101, 138, 153 and 180). The results showed that the impact of PCB emissions into the river is higher in summer than in other seasons due to the low flow rate of the river during this period. Polar organic chemical integrative samplers (POCIS) were deployed for 4 months in the Sion-Riddes canal (VS) to investigate herbicides (terbuthylazine, diuron and linuron). Desisopropylatrazine-d5 (DIA-d5) was tested as a performance reference compound (PRC) to estimate aqueous concentration. The results showed an increase of water contamination due to the studied agricultural area. The maximal contamination was observed in April and corresponds to the period of herbicide application on the crops.

The Magnitude and Spatial Range of Current-Use Urban PCB and PBDE Emissions Estimated Using a Coupled Multimedia and Air Transport Model

SO-MUM, a coupled atmospheric transport and multimedia urban model, was used to estimate spatially resolved (5 × 5 km(2)) air emissions and chemical fate based on measured air concentrations and chemical mass inventories within Toronto, Canada. Approximately 95% and 70% of Σ5PCBs (CB-28, -52, -101, -153, and -180) and Σ5PBDEs (BDE-28, -47, -100, -154, and -183) emissions of 17 (2-36) and 18 (3-42) kg y(-1), respectively, undergo atmospheric transport from the city, which is partly over Lake Ontario. The urban air plume was found to reach about 50 km for PCBs and PBDEs, in the direction of prevailing winds which is almost twice the distance of the wind-independent plume. The distance traveled by the plume is a function of prevailing wind velocity, the geographic distribution of the chemical inventory, and gas-particle partitioning. Soil wash-off of historically accumulated Σ5PCBs to surface water contributed ∼ 0.4 kg y(-1) (of mainly higher congeners) to near-shore Lake Ontario compared with volatilization of ∼ 6 kg y(-1) of mainly lighter congeners. Atmospheric emissions from primary sources followed by deposition to surface films and subsequent wash-off to surface water contributed ∼ 1 kg y(-1) and was the main route of Σ5PBDE loadings to near-shore Lake Ontario which acts as a net PBDE sink. Secondary emissions of PCBs and PBDEs from at least a ∼ 900,000 km(2) rural land area would be needed to produce the equivalent primary emissions as Toronto (∼ 640 km(2)). These results provide clear support for reducing inventories of these POPs.

PCDD/DF and co-planar PCB emissions from crematories in Japan

Japan implemented dioxin emission guidelines for crematories in 2000, but the effects of the new guidelines have not been fully evaluated. In this study, concentrations of polychlorinated dibenzodioxins/dibenzofurans (PCDDs/DFs) and co-planar polychlorinated biphenyls (co-PCBs) were measured in flue gas, fly ash, and bottom ash (mainly bone) from several crematories as a follow-up investigation. Total concentrations (O2 12% normalized) of PCDDs/DFs and co-PCBs in flue gas ranged from 4.2to540ng/mN3, and toxic equivalent concentrations ranged from 0.000053 to 11ng-TEQ/mN3. Based on these measurements, the average emission factor was estimated to be 1400ng-TEQ/body. This is approximately one-third the emission factor recorded in 1999. The emission factor distributions from 1999 and our study in 2007 were log-normally distributed. Emission factors were significantly lower in 2007 than in 1999, which suggests that the guidelines have been effective in reducing dioxin emissions. Meanwhile, toxic equivalent concentrations in fly ash ranged from 0.014 to 13ng-TEQg−1. Higher dioxin concentrations in fly ash were observed in facilities that used a heat exchanger as a flue-gas cooling device. Because the concentrations of PCDDs/DFs and co-PCBs in flue gas were also elevated after heat exchangers during the investigation of PCDD/DF- and co-PCB-removal behaviors, secondary formation of PCDDs/DFs and co-PCBs on heat exchanger surfaces unambiguously occurred.

SO-MUM: A Coupled Atmospheric Transport and Multimedia Model Used to Predict Intraurban-Scale PCB and PBDE Emissions and Fate

A spatially resolved, dynamic version of the Multimedia Urban Model (MUM) and the boundary layer forecast and air pollution transport model BLFMAPS were coupled to build Spatially Oriented MUM (SO-MUM), to estimate emissions and fate of POPs in an urban area on a 5 × 5 km(2) cell resolution. SO-MUM was used to back-calculate emissions from spatially resolved measured air concentrations of PCBs and PBDEs in Toronto, Canada. Estimated emissions of Σ(88)PCBs were 230 (40-480) kg y(-1), 280 (50-580) g y(-1) km(-2), or 90 (16-190) mg y(-1) capita(-1), and Σ(26)PBDEs were 28 (6-63) kg y(-1), 34 (7-77) g y(-1) km(-2), or 11 (2-25) mg y(-1) capita(-1). A mass inventory of penta- and octa-BDEs in Toronto was estimated to be 200 tonnes (90-1000 tonnes) or 80 (40-400) g capita(-1). Using this estimate and that of 440 (280-800) tonnes of PCBs, estimated emissions of Σ(88)PCBs and Σ(26)PBDEs per mass of chemical inventory in Toronto were 0.5 (0.05-1.6) and 0.1 (0.01-0.7) g y(-1) kg(-1), respectively. The results suggest annual emission rates of 0.04% and 0.01% from the mass inventories with downtown accounting for 30% and 16% of Toronto's chemical inventory and emissions of PCBs and PBDEs, respectively. Since total PBDE emissions are a function of mass inventory, which is proportional to building volume, we conclude that building volume can be used as a proxy to predict emissions. Per mass inventory emission rates were negatively related to vapor pressure within a compound class, but not consistently when considering all compound congeners.

Chiral Signatures Show Volatilization from Soil Contributes to Polychlorinated Biphenyls in Grass

Enantiomer fractions (EFs) of PCB 95 and concentrations of PCBs 28/31, 52, 101, 118, 138, 153, and 180 were determined in air. Samples were taken at ~14 day intervals on a vertical gradient at an urban background site in Birmingham U.K. in summer 2009 (114 days) and spring 2010 (84 days). EFs in air at 3 cm height were nonracemic (average 0.453 (2009) and 0.468 (2010)) and differed significantly (p < 0.05) from the racemic EFs in air at 10, 40, 90, and 130 cm. EFs in soil (average 0.452 (2009) and 0.447 (2010)) closely matched those in air at 3 cm, while those in grass (average 0.468 (2009) and 0.484 (2010)) were intermediate between those in soil and the racemic EFs in air at ≥ 10 cm. This implies that at the study site, PCBs volatilize from soil to an extent discernible only at the soil:air interface, and that PCBs in grass arise due to foliar uptake of volatile emissions from soil. Atmospheric concentrations of ΣPCBs increased significantly (p < 0.05) with increasing height. Combined with the chiral signature data, this suggests the influence of PCB emissions from soil on airborne concentrations decreases with altitude, while that of emissions from the built environment increases.

Estimation of PCB Stocks, Emissions, and Urban Fate: Will our Policies Reduce Concentrations and Exposure?

PCBs, used to manage risks from the flammability of dielectric fluids and to increase the durability of elastic sealants, had declining environmental concentrations after legislation banning new production was passed during the 1970s and 1980s in Europe and North America. To answer why PCB temporal trends are now nearly stable and if current policies will further reduce concentrations and our exposure, we estimated PCB stocks in Toronto, Canada (population of approximately 2.5 million) of 437 (282-796) tonnes, of which 97 and 3% are in closed sources and building sealants, respectively. The greatest geographic density of PCBs is downtown, specifically in commercial, electricity-intensive skyscrapers. An unknown stock is within now-buried landfills and other waste-handling facilities as well as diffuse sources such as electrical wiring and paints. Using the Multimedia Urban Model, we estimated city-wide emissions of approximately 0.14-1.4 mg m(-2) y(-1) or 35-350 mg capita(-1) y(-1) of SigmaPCB(70), which is approximately 0.01-0.3% annually of total documented stocks. Canada, as one of 159 signatories of the Stockholm Convention and the 35 parties that have reported progress toward environmentally sound management of their PCB inventories by 2028, has passed national legislation with a timetable of inventory reductions. It is unclear whether this legislation will successfully reduce concentrations and exposures, however the analysis should inform our management of other contaminants.

Assessing PAH and PCB emissions from the relocation of harbour sediments using equilibrium passive samplers

Large-scale dredging of contaminated sediments is taking place in the harbor of Oslo, Norway. The dredged sediment masses are transferred into a confined aquatic disposal facility (CAD) in a natural 70-m deep basin within the Oslofjord. Currently there is no established method to determine how much dissolved contaminants are released during relocation and deposition of these sediments. For this reason we tested the use of equilibrium passive samplers consisting of 55μm thin polyoxymethylene (POM-55) for studying the release of freely dissolved and thus bioavailable PAHs and PCBs at the disposal site, and found this to be a suitable method. In order to use POM-55 for monitoring PCBs, it was necessary to measure their POM-55/water partition coefficients, which was also presented as part of this study. Elevated turbidity (average 4.1mgl−1) was observed at one side of the basin where no natural sill exists. Analysis of POM-55 at this location before and after deposition revealed that there was an increase in freely dissolved concentrations (CW,free) during deposition by a factor 37.5 for PAHs and a factor of 2.9 for PCBs. In addition, during deposition phenanthrene-to-anthracene aqueous concentration ratios at this location (values of 3–4) were more similar to those of the deposited sediments (∼2) than to those of the CAD water prior to deposition (∼14). This was not observed for the other locations where a natural sill exists at approximately 30m water depth. The POM-55 equilibrium passive samplers are here shown to be useful tools for measuring and understanding the dynamics involved in the release of dissolved contaminants during sediment relocation.

GEM/POPs: a global 3-D dynamic model for semi-volatile persistent organic pollutants – Part 2: Global transports and budgets of PCBs

Abstract. Global transports and budgets of three PCBs were investigated with a 3-D dynamic model for semi-volatile persistent organic pollutants – GEM/POPs. Dominant pathways were identified for PCB transports in the atmosphere with a transport flux peaking below 8 km for gaseous and 14 km for particulate PCB28, and peaking below 4 km for gaseous and 6 km for particulate PCB180. The inter-continental transports of PCBs in the Northern Hemisphere (NH) are dominated in the zonal direction with their route changes regulated seasonally by the variation of westerly jet. The transport pathways from Europe and North Atlantic contributed the most PCBs to the Arctic. Inter-hemispheric transports of PCBs originated from the regions of Europe, Asia and North America in three different flow-paths, accompanying with easterly jet, Asian monsoon winds and trade winds. PCBs from the Southern Hemisphere (SH) could also be exported into the NH. According to the PCB emissions of year 2000, Europe, North America and Asia are the three largest sources of the three PCBs, contributing to the global background concentrations in the atmosphere, soil and water. Globally, PCB28 in soil and water has become a comparable source to the anthropogenic emissions while heavier PCBs such as PCB153 and 180 are still transporting into soil and water. For all three congeners, particulate PCBs are concentrated in the higher levels than gaseous PCBs. More than half of the particulate PCB28 could reach up to the stratosphere, while most of the heavier counter-parts (PCB153 and PCB180) are stored in the troposphere including boundary layer with more than 99% gaseous PCB180 below 6 km.

Towards a global historical emission inventory for selected PCB congeners — A mass balance approach

Previously published estimates of the global production, consumption and atmospheric emissions of 22 individual PCB congeners [Breivik K, Sweetman A, Pacyna JM, Jones KC. Towards a global historical emission inventory for selected PCB congeners – a mass balance approach. 1. Global production and consumption. Sci Total Environ 2002a; 290: 181-198.; Breivik K, Sweetman A, Pacyna JM, Jones KC. Towards a global historical emission inventory for selected PCB congeners – a mass balance approach. 2. Emissions. Sci Total Environ 2002b; 290: 181-198.] have provided useful information for later studies attempting to interpret contaminant levels in remote areas as well as in the global environment. As a result of the need for more contemporary emission data (following the year 2000), an update of this emission database is presented. This exercise takes into account new information on PCB production in Poland, as well as new data on the chemical composition of various technical mixtures for which less information had been available. The methodology to estimate temporal trends of PCB emissions associated with various types of PCB usage is improved. Projected emissions up to year 2100 are presented to facilitate predictions of future environmental exposure. The national emission data for each of the 114 countries considered is spatially resolved on a 1° × 1° grid for each congener and year, using population density as a surrogate.

PCDD/F and “Dioxin-like” PCB emissions from iron ore sintering plants in the UK

Investigations have been carried out at the three Corus UK sinter plants over the period 2002–2004 to characterise the emissions of both 2,3,7,8-PCDD/Fs and WHO-12 PCBs, to estimate annual mass releases of these organic micro-pollutants using the I-TEF and WHO-TEF schemes, and to investigate the formation of PCBs in the iron ore sintering process. Results showed that the sintering of iron ore produces a characteristic WHO-12 PCB and PCDD/F congener pattern that is substantially the same for all UK sinter plants. With regard to WHO-12 PCBs, the most abundant congeners were typically PCBs 118 (6–9 ng N m −3), 105 (2–4 ng N m −3) and 77 (2–3 ng N m −3). All other WHO-12 PCBs were also detected at concentrations around 1 ng N m −3. All sinter plants investigated exhibited very similar TEQ concentrations. WHO-12 PCB emissions were in the range 0.042–0.111 ng WHO-TEQ N m −3, whereas PCDD/F emissions ranged from 0.39 to 1.62 ng WHO-TEQ N m −3. PCDF congeners were the main contributors to the overall TEQ in sintering emissions (ca. 85%). Amongst WHO-12 PCBs, PCB 126 was the only noteworthy contributor to total TEQ (ca. 5–7%), a similar contribution to that from PCDDs. Based on the measurements that Corus UK has undertaken at these three sinter plants, annual mass releases of WHO-12 PCBs and PCDD/Fs have been calculated. For UK sinter plants, a total mass release of 29.5 g WHO-TEQ per annum [WHO-12 PCBs + PCDD/Fs] has been estimated, representing 9% of the total PCDD/F emissions to the UK atmosphere. Measurements were also carried out at a UK sinter plant to determine the windleg emission profile of WHO-12 PCBs. Results showed that WHO-12 PCBs were formed in the same regions of the sinter strand as 2,3,7,8-PCDD/Fs, indicating that there was a strong correlation between the formation of WHO-12 PCBs and PCDD/Fs in the iron ore sintering process.

The impact of urban areas on the deposition of air toxics to adjacent surface waters: A mass budget of PCBs in Lake Michigan in 1994

The impact of urban air toxics on the proximate water bodies was investigated as part of the AEOLOS Project (Atmospheric Exchange Over Lakes and Oceans). The hypothesis of this project was that emissions of hazardous air pollutants into the coastal urban atmosphere increased atmospheric depositional fluxes to proximate Great Waters. Areas of major field and modeling campaigns were located in southern Lake Michigan near Chicago, IL and northern Chesapeake Bay near Baltimore. The impact on Lake Michigan of PCB emissions from the urban area of Chicago was evaluated through field experiments to determine atmospheric concentrations, surface water concentrations, wet and dry deposition and bi-directional gas exchange. These values were used to construct a PCB mass budget for the Lake Michigan ecosystem, which includes the urban influence. PCB emissions in the Chicago atmosphere lead to dramatically increased atmospheric concentrations of PCBs off shore and significantly increased wet, dry particle and air-water exchange fluxes in southern Lake Michigan compared to the regional signal. High PCB concentrations occur over the lake only when the wind is from the direction of the urban/industrial complex inclusive of the shoreline from Gary, IN to Evanston, IL toward the lake. Although atmospheric loading of PCBs was much higher in the southern basin of Lake Michigan, water column concentrations have significantly decreased from 1980 to 1994 through the rapid uptake by settling particles, and have continued to decrease at a rate of 0.17 yr−1. In contrast to earlier PCB mass budgets that missed significant inputs, outputs and/or process terms, inclusion of the urban-influenced air-water exchange processes and a re-evaluation of new lake data effectively closed the PCB budget for Lake Michigan. Atmospheric exchange processes dominated the whole lake budget. The Chicago area, with high industrial density, emits large quantities of hazardous organic pollutants and has important impacts on the down wind coastal atmosphere and proximate surface waters.

Improvements to the UK PCDD/F and PCB atmospheric emission inventory following an emissions measurement programme

PCDD/F data are presented from 75 samples of primary emissions sampled between 1995–1997 as part of the compliance monitoring survey undertaken by the UK Environment Agency. Municipal solid waste (MSW), chemical waste and clinical waste incinerators, cement kilns, sinter plants and sewage sludge incinerators were the source categories monitored and reported here. Based on this monitoring programme, the previous national UK emission estimates by Eduljee and Dyke (1) of 560–1100 g I-TEQ a −1 for 1993 have been revised downwards to 220–660 g I-TEQ a −1. Despite source reduction measures, MSW incinerators remain a significant source of PCDD/Fs to the atmosphere, contributing between 30–50% of the ΣPCDD/F I-TEQ emission, rather than the ∼80% they were estimated to contribute in 1993. 2,3,7,8-substituted PCDD/F congener profile data are presented for some of the source categories and generally support the view that differences in the mixtures (‘fingerprints’) of PCDD/Fs emitted from different sources are observed. New data on the dioxin-like PCB emissions are presented for cement kilns and sinter plants. These show that TEQ-rated PCBs can make an important contribution to the I-TEQ emitted from certain combustion sources. High concentrations of a full range of PCB congeners/homologues have been measured in the atmosphere close to sintering strands, although the precise source of PCBs from this process remains unclear.

Ecological assessment of a region with PCB emissions using samples of soil, vegetation and breast milk: a case study

An ecological assessment is performed by using a data bank of air, soil, vegetation and biology data from the area of a capacitor plant in Serpukhov, Russia. Over a number of years the use of PCBs for filling capacitors has brought about environmental contamination beyond the plant's sanitary zone, in particular along a stream where vegetables and berries are grown commercially. A correlation has been found between abnormally high concentrations of PCBs in breast milk of women living in the proximity of the plant and the occurrence of diathesis in babies. A number of remedial measures have been developed in conjunction with the city's sanitary service.

PCDD, PCDF and PCB emissions under variable operating conditions from a waste oil furnace

The levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in the furnace and stack emissions of a waste oil furnace were measured under four different operating conditions.

Analysis of PAH and PCB emissions generated during the combustion of binder enhanced densified refuse derived fuel

Our research group has been involved in developing a binding agent to add to pelletized densified refuse derived fuel (dRDF). Initial tests showed that Ca(OH) 2 is effective in reducing the rate of degradation of dRDF pellets. Further tests were done analyzing the affect of this binder on PAH and PCB emissions. Both PAH and PCB emissions were reduced considerably upon the addition of four to eight percent binder to the pellets.

Are video display terminals a source of increased PCB concentration in the working atmosphere? One answer.

In response to the question: "Are datascreen terminals a source of increased PCB concentrations in the working atmosphere?" a study of PCB emissions from video display terminals (VDT) was undertaken. Emissions of 2.4 to 8.1 ng PCB/h were observed from VDT located in a building (1) where the mean PCB level in the air was 46 ng PCB/m3 during the test period, whereas no PCB emissions were detected from VDT located in a building (2) where no PCB could be detected in the ambient air. However, both the air and the VDT from building 2 were found to be contaminated with polycyclic aromatic hydrocarbons. We conclude that the observed PCB emissions from VDT are the result of the vapourization of PCB deposited onto the VDT from the PCB contaminated air and do not originate from the electrical components of the VDT.