Smoke-haze pollution: a review of the 1997 episode in Southeast Asia

In the second half of 1997, large areas in Southeast Asia were severely affected by a smoke-haze pollution episode caused by the emissions of an estimated 45,600 km² of vegetation that burnt on the Indonesian islands Kalimantan and Sumatra. To document the impacts of these fires on air quality, data for total suspended particulate matter (TSP) and for particulate matter below or equal to 10 microns in diameter (PM₁₀) from selected sites in Indonesia, Malaysia and Singapore are analysed in this paper. These data are supplemented by meteorological data, satellite images and a summary of related research. TSP was above 2,000 μg m^–3 for several days in Indonesian locations close to the most extensive fire activity. In Malaysia and Singapore, ambient particle concentrations increased to several times their average September levels. Characteristically for emissions from vegetation burning, the additional atmospheric particle loading during the smoke-haze episode was predominantly due to an increase of the fraction below or equal to 2.5 microns in diameter (PM_2.5). Due to the dominance of respirable particles (PM_2.5) in the smoke-haze, air quality reporting based on TSP or PM₁₀ may be inadequate to assess the health risk. Upgrading of PM_2.5 monitoring facilities is therefore needed. Reducing the probability of similar smoke-haze events in future would require appropriate fire use and smoke management strategies. Electronic Publication     

Radiological impact of coal-fired power generation

A radiological impact assessment was carried out at the 4000 MW Nanticoke Thermal Generating Station on the north shore of Lake Erie and at an ash disposal site in Metropolitan Toronto, both operated by Ontario Hydro. Analyses were performed on feed coal, fly ash and bottom ash and on samples of air filters, precipitation, water, soil and vegetation in the vicinity of the generating station. The measured radionuclide levels in the vicinity of the generating station showed no evidence of enhancement from station emissions. There were no indications that leaching of radionuclides or emanation of radon gas from ash disposal sites would be a problem. There was evidence, however, of higher radionuclide concentrations on the finer ash particles. Furthermore, the use of fly ash in building materials could lead to enhanced radiation levels. Atmospheric dispersion and radiation dose calculations were also carried out. Predicted concentrations in air were all less than 1% of background values. The committed dose equivalent from one year of operation was estimated to be 0·27 μSv at the site boundary and 0·11 μSv at 10 km east of the site.     

Size dependent cytotoxicity of fly ash particles

Fly ash samples were collected from the electrostatic precipitator of a coal-fired power plant in Hong Kong. The particles of the respirable range (smaller than 10 μm) were divided into 4 groups according to their particle size (mass median aerodynamic diameters). The surface morphology and the metal contents (Fe, Mn, Al and Zn) of fly ash particles were examined by a scanning electron microscope and an inductively coupled plasma spectrophotometer, respectively. The particles were very heterogenous in size and shape as well as the concentration of metals. The cytotoxicity of these four groups of fly ash particles was evaluated using an in vitro rat alveolar macrophages culture assay. The viability of alveolar macrophages was lower when incubated with smaller size particles. This relationship was also reflected by the damage of the surface morphology of the cells and the release of cytoplasmic (lactate dehydrogenase) and lysosomal (acid phosphatase and β-glucuronidase) marker enzymes into the culture media.     

Application of slipstreamed air pollution control devices on waste-as-fuel processes

The recovery of energy from the combustion of municipal solid wastes is becoming an attractive alternative as landfill space becomes scarce and the availability of fossil fuels decreases. Particulate emissions from “waste-as-fuel” processes, however, may differ significantly in chemical and physical properties from particulate emissions produced by firing only coal. Such differences can affect the design and operation of air pollution control equipment. Presented in this paper are the results of a 2-month test program at Ames, Iowa, with a mobile electrostatic precipitator (ESP) and a mobile scrubber supplied by the U.S. Environmental Protection Agency (EPA), Industrial Environmental Research Laboratory (IERL), Research Triangle Park. PEDCo Environmental, Inc., and Acurex Corporation jointly conducted the test program to examine the effect of burning refuse-derived fuel (RDF) on particulate and heavy metal control efficiencies. The mobile ESP was used only as a primary control device, whereas the mobile scrubber was tested both upstream and downstream of the existing full-scale ESP. This paper also presents a status report on a PEDCo test program with a pilot fabric filter at Ames.     

Fabric filters versus electrostatic precipitators

Control of particulate emissions from pulverized coal fired steam generators is becoming a significant factor in the siting and public acceptability of large coal burning power plants. The particulate emission limit established by the EPA for new coal fired boilers is 0.03 lb/10⁶ Btu (13 ng/J) Possibly more restrictive than this is the state of New Mexico's particulate regulation which calls for no more than 0.05 lb/10⁶ Btu (22 ng/J) total, and no more than 0.02 lb/10⁶ Btu (9 ng/J) less than 2 microns in diameter. This paper will evaluate the effect of these stringent limitations on the technical feasibility and economics of dry particulate removal. Electrostatic precipitators have been the dominant particulate collection device in the electric utility industry for many years because of their low capital and operating cost. However, increasingly stringent emission standards have led to substantially higher costs for precipitators. These costs have increased sufficiently for fabric filtration to become a competitive alternative in achieving cost effective control. This paper will compare the economics and performance of fabric filtration with respect to conventional electrostatic precipitators. The paper will also address the preliminary evaluation procedures that should be followed in order to select the appropriate device for new or existing coal-fired boilers.     

京津冀PM_(2.5)的主要影响因素及内在关系研究

大气污染物的源排放是形成灰霾天气的内因,气象条件是形成灰霾天气的外因。本研究通过构建PM_(2.5)浓度的两段式分布滞后模型,结合自然环境因素及经济因素对PM_(2.5)的影响因素进行了综合分析。在第一段模型中构建了PM_(2.5)和大气污染物排放量的分布滞后模型,第二段模型中构建了不同的大气污染源对大气污染物排放量的影响因素模型。大气污染物排放源主要包括工业源、生活源、机动车源、集中式污染治理设施源。在工业源中,工业废气重度污染行业是大气污染物排放主要的贡献者;在生活源中,燃煤消费量对大气污染物排放影响很大,这也是冬季供暖期间PM_(2.5)剧增的原因;在机动车源中,尽管黄标车的保有量仅占汽车保有量的10%左右,但却占据了颗粒物排放量的绝大部分。利用京津冀代表性城市PM_(2.5)日度数据研究得出平均气温、平均风速、日照时数、平均气压、降雨量、平均相对湿度、沙尘暴等因素对PM_(2.5)浓度的负向与正向作用。研究发现,大气污染物排放量对PM_(2.5)浓度具有聚集的滞后效应,当期大气污染物排放量、滞后一期、滞后两期、滞后三期大气污染物对PM_(2.5)浓度具有显著的正向作用,且影响依次递减。构建的大气污染物排放量的污染源影响因素模型揭示一个地区煤炭消费量、工业废气重度污染行业工业增加值、黄标车保有量对该地区大气污染物排放量具有显著影响。本研究对优化能源消费结构和产业结构,减少空气污染物排放提出了对策建议。     

Development and analysis of high-performance green concrete in the urban infrastructure

Cement production accounts for approximately 5% of total global CO₂ emissions from all human activities. In addition, the consumption of virgin aggregates for concrete infrastructure has created virgin material scarcity issues in many areas of the USA. High-performance green concrete (HPGC) with fly ash and recycled aggregates can help reduce the demand for material inputs and reduce pollution outputs associated with bulk material flow of urban concrete. Structural and durability tests showed that HPGC containing fly ash and 50% recycled aggregate (100% of the coarse aggregate fraction) performed equally or better than 100% ordinary Portland cement concrete with the same cementitious content. Durability improvements were more significant with Class F than Class C fly ash. For both Class F and Class C fly ash, greater per cent replacement of Portland cement with fly ash led to slower and lower strength gain, but still within acceptable strength criteria for Colorado Department of Transportation Class B concrete. This paper quantifies the sustainability of HPGC in urban infrastructure by addressing structural performance, environmental, economic and resource depletion impacts.     

Distribution of PBDEs in air particles from an electronic waste recycling site compared with Guangzhou and Hong Kong, South China

Air samples of total suspended particles (TSP, particles less than 30-60 microm), and particles with aerodynamic diameter smaller than 2.5 microm (PM(2.5)) were collected simultaneously at Guiyu (an electronic waste recycling site), three urban sites in Hong Kong and two urban sites in Guangzhou, South China from 16 August to 17 September 2004. Twenty-two PBDE congeners (BDE-3, -7, -15, -17, -28, -49, -71, -47, -66, -77, -100, -119, -99, -85, -126, -154, -153, -138, -156, -184, -183, -191) in TSP and PM(2.5) were measured. The results showed that the overall average concentrations of TSP and PM(2.5) collected at Guiyu were 124 and 62.1 microg m(-3), respectively. The monthly concentrations of the sum of 22 BDE congeners contained in TSP and PM(2.5) at Guiyu were 21.5 and 16.6 ng m(-3), with 74.5 and 84.3%, contributed by nine congeners (BDE-28, -47, -66, -100, -99, -154, -153, -183 and -191 respectively). This pattern was similar to Tsuen Wan site of Hong Kong. Two urban sites of Guangzhou had the same congener pattern, but were different from Yuen Long and Hok Tsui sites of Hong Kong. The results also showed that the amount of mono to penta brominated congeners, which are more toxic, accounted for 79.4-95.6% of Sigma(22)PBDEs from all sites. All congeners tested in Guiyu were up to 58-691 times higher than the other urban sites and more than 100 times higher than other studies reported elsewhere. The higher concentration in the air was due to heating or opening burning of electronic waste since PBDEs are formed when plastics containing brominated flame retardants are heated.     

Chemical speciation and phytoavailability of Zn, Cu, Ni and Cd in soil amended with fly ash-stabilized sewage sludge

A sequential extraction method was used to determine chemical forms of Cu, Zn, Ni and Cd in fly ash-stabilized sludge. A loamy acid soil amended with fly ash-stabilized sludge was used to grow corn under greenhouse conditions. Sewage sludge amended with coal fly ash can reduce the availability of Cu, Zn, Ni and Cd in the sludge. Increasing fly ash amendment rate significantly reduced DTPA-extractable Cu, Zn, Ni and Cd concentrations. Percentages of Cu, Zn and Ni in residual fraction increased with an increase in fly ash amendment rates. Majority of Cu was associated with organic form, but Zn and Ni were associated with Fe-Mn oxide and residual forms. Addition of ash-amended sludge to soil significantly increased dry mass of corn. With coal fly ash amendment rate increasing, concentrations of Zn and Cu in shoot tissues of corn decreased significantly, but concentrations of Cd and Ni did not change significantly. Significant correlations were found between concentrations of Cu and Zn in corn shoot and oxide and total Cu fractions, and all chemical fractions of Zn in fly ash-stabilized sludge, respectively. Hence, ash amendment significantly reduced the availability of heavy metals by chemical modification of their chemical speciation into less available forms.     

Soil dust: A major contributor to the total suspended particulate matter in Bombay

Estimates of source contribution are important for setting more realistic air quality standards for total suspended particles (TSP). Soil dust contributes a major fraction of the atmospheric particulate load in India during the dry months. Chemical element balance (CEB) analysis shows that nearly 50% to 60% of the TSP in Bombay during winter months are of crustal origin. Wind-raised dust from parched earth surface and traffic dust from badly maintained roads are the probable causes of the observed higher contribution of soil dust.     

Polycyclic aromatic hydrocarbons in ambient air particles in the city of Las Palmas de Gran Canaria

Concentration levels, seasonal variation and winter/summer ratios of 11 polycyclic aromatic hydrocarbons (PAHs) in the TSP of Las Palmas de Gran Canaria city were determined. The study area is under the influence of heavy traffic (80000 vehicles/day). Pyr/BaA, Pyr/Flt, B(ghi)P/I(cd)P and B(b+k)F/B(ghi)P ratios were calculated; the values of these two last suggest a strong influence of diesel fuel burning. Levels of TSP and TSP-bound PAHs were also established. The hazard potential of PAHs in terms of carcinogenicity of BaP is acceptable. Potential risk on the basis of TEFs is also studied.     

Precipitator upgrading and fuel control program for particulate compliance at Pennsylvania power and light company

Two cold side electrostatic precipitators handling low sulfur eastern bituminous coal flyash were upgraded from 94% to 99.4% efficiency in order to meet a particulate compliance limit of 0.1 lb/MMBtu (43 ng/J).The comprehensive upgrading was the result of a 2 year research and testing program during which various aspects of flue gas conditioning, electrical energization, rapping, coal quality control, and gas distribution were independently tested on three similar precipitators. The ensuing upgrading program included the installation of hardware for maximum performance and reliability as well as flue gas conditioning and a fuel ash control program.A cost and reliability analysis of the upgrading program as compared with the installation of an additional series precipitator is included.     

Characterising the performance of a tapered scrubber for controlling particulate emission

The performance of a modified tapered scrubber using water is presented in this article. The column is fabricated with internals so as to improve the performance of a simple tapered bubble scrubber. Experimentation indicates that the system developed can obtain almost 100% particulate (fly ash) removal efficiency under certain hydrodynamical conditions and the removal efficiency has been found to be higher than the existing similar systems. An empirical correlation is put forward for the prediction of removal efficiency as a function of relevant variables of the system. Experimental results agree very well with the correlation.     

Wintertime indoor air levels of PM10, PM2.5 and PM1 at public places and their contributions to TSP

From 26 October 2002 to 8 March 2003, particulate matter (PM) concentrations (total suspended particles [TSP], PM10, PM2.5 and PM1) were measured at 49 public places representing different environments in the urban area of Beijing. The objectives of this study were (1) to characterize the indoor PM concentrations in public places, (2) to evaluate the potential indoor sources and (3) to investigate the contribution of PM10 to TSP and the contributions of PM2.5 and PM1 to PM10. Additionally, The indoor and outdoor particle concentrations in the same type of indoor environment were employed to investigate the I/O level, and comparison was made between I/O levels in different types of indoor environment. Construction activities and traffic condition were the major outdoor sources to influence the indoor particle levels. The contribution of PM10 to TSP was even up to 68.8%, while the contributions of PM2.5 and PM1 to PM10 were not as much as that of PM10 to TSP.     

Predicting fly ash resistivity—an evaluation

Recently a technique for predicting fly ash resistivity from an as-received, ultimate coal analysis and the chemical composition of the coal ash produced by simple laboratory ignition was published. This paper evaluates this technique by comparing predicted resistivity data with laboratory measured values, in situ resistivity data, and precipitator performance information acquired from 12 field test programs. Considering the precision of measurement generally encountered in precipitator technology and the limited amount of certain laboratory data available, the results are encouraging and the evaluation is favorable.     

Enhancement of population doses due to production of electricity from brown coal in Poland

Changes in natural radioactivity as a result of the operations of three Polish brown-coal-fired power plants have been assessed via calculations based on the results of radio-spectrometric measurements of coal and fly ash, information on local climatic conditions and data on atmospheric releases from the plants. Calculations were performed using a computer code derived from solution of the Pasquille equation. Transfer coefficients and conversion factors of absorbed radioactivity to effective dose equivalent (EDE) were selected using literature data. Values for EDE due to inhalation, ingestion and external gamma radiation from radionuclides deposited on the ground were calculated for the population inhabiting the most polllated area and also for the whole population. The individual maximum EDE for the most ‘radioactive’ power plant was estimated at 10·4 μSv y⁻¹. This EDE is less than 1% of the total natural radiation burden of 2 mSv y⁻¹. EDE estimates for the vicinities of the other two power plants are 0·5 and 4·2 μSv y⁻¹. The collective EDE resulting from the production of electrical energy from brown coal was calculated to be 104 man-Sv y⁻¹, i.e. 14 man-Sv per GW-year. It is concluded that some of the brown-coal-fired power plants in Poland should improve their fly ash control and that the manner in which existing transfer coefficients are reported in the literature does not lead to unequivocal results when applied to EDE calculations.     

Revegetating fly ash landfills with Prosopis juliflora L.: impact of different amendments and Rhizobium inoculation

A revegetation trial was conducted to evaluate the feasibility of growing a legume species, Prosopis juliflora L., on fly ash ameliorated with combination of various organic amendments, blue-green algal biofertilizer and Rhizobium inoculation. Significant enhancements in plant biomass, photosynthetic pigments, protein content and in vivo nitrate reductase activity were found in the plants grown on ameliorated fly ash in comparison to the plants growing in unamended fly ash or garden soil. Higher growth was obtained in fly ash amended with blue-green algae (BGA) than farmyard manure or press mud (PM), a waste from sugar-processing industry, due to the greater contribution of plant nutrients, supply of fixed nitrogen and increased availability of phosphorus. Nodulation was suppressed in different amendments of fly ash with soil in a concentration-duration-dependent manner, but not with other amendments. Plants accumulated higher amounts of Fe, Mn, Cu, Zn and Cr in various fly ash amendments than in garden soil. Further, inoculation of the plant with a fly ash tolerant Rhizobium strain conferred tolerance for the plant to grow under fly ash stress conditions with more translocation of metals to the above ground parts. The results showed the potential of P. juliflora to grow in plantations on fly ash landfills and to reduce the metal contents of fly ash by bioaccumulation in its tissues.     

Evaluation of genotoxic and non-genotoxic effects of organic air pollution using in vitro bioassays

In this study, organic extracts of total suspended particles (TSP) and the particulate matter (PM) with the size below 2.5 microm (PM(2.5)) combined with organic extracts of the gas phase (GP) collected at two urban and two background localities were analyzed with a bacterial genotoxicity test, SOS chromotest, and an in vitro test for the dioxin toxicity determination, using a modified cell-line of rat hepatoma H4IIE.luc. In addition, the samples of TSP and GP were analyzed for PAHs contents. The PAHs concentrations and both of the toxic activities at the urban localities were much higher than ones at the background localities. Predominantly, traffic was a source of the urban air pollution there which was also confirmed by the evaluation of portions of certain PAHs (BaP/BPE, PYR/BaP) at the localities. On the other hand, the background localities were apparently affected by a long-distance transport of the pollutants from urban and industrial centers. The results of the bioassays indicated potential health risks for the population exposed to the organic air pollutants, especially at the urban localities. Based on the collected samples, distribution of the organic pollutants with the toxic effects in the air was evaluated. The significant portion of the direct genotoxins was bound to the particles larger than 2.5 microm. On the contrary, the indirect genotoxins were bound predominantly to the particles with the size below 2.5 microm. However, in the urban air they may be also bound to the larger particles, as well. While the direct genotoxicity may be related with the presence of PAH-derivatives as well as some polar organic pollutants, the indirect genotoxicity is related with the detected carcinogenic PAHs. But besides the above specified pollutants it is also necessary to consider the presence of other toxic components of the complex organic air pollution mixture that may also show potential health risks. This study demonstrates application of the combination of the screening bioassays for the evaluation of organic air pollution and identification of its health risks.     

Ventilation requirements in occupied spaces during smoking and nonsmoking occupancy

Ventilation requirements in occupied spaces have traditionally derived largely from odor control. The requirements have rested on the notion that an environment that seems subjectively acceptable to a visitor will in fact be healthful and comfortable for both visitor and occupant alike. Ventilation requirements have derived secondarily from criterion concentrations of notable contaminants (e.g., carbon dioxide). The present investigation looked again at both sensory (odor, irritation) and physical criteria of acceptability, paying particular attention to the difference between smoking and nonsmoking occupancy in a well-controlled environmental chamber. More than 200 persons (visitors) made judgments of odor intensity and acceptability under various conditions of occupancy (up to 12 nonsmoking occupants; a temperature of up to 25.5°C; up to 16 cigarettes smoked per hour). The results implied that under nonsmoking conditions and moderate humidity only about 7.5 cfm (3.8 L sec⁻¹) of fresh air per occupant sufficed to satisfy visitors, but that under smoking conditions at least 5 times as much fresh air is necessary. Our estimate of ventilation requirements for smoking were derived in part from measurements of carbon monoxide and total suspended particulate (TSP) mass concentration. Levels of TSP achieved during realistic smoking and ventilation rates exceeded levels deemed acceptable outdoors. Surfaces in the chamber played an important role in the elimination of particles, presumably via adsorption. Use of an electrostatic precipitator could keep TSP levels under control. Nevertheless, it remains to be seen whether control of TSP will eliminate the need for enormous ventilation for odor control during smoking occupancy.     

Environmental impact and human exposure to PCBs in Guiyu, an electronic waste recycling site in China

PCB levels in fish (collected from local rivers), atmosphere and human milk samples have been studied to determine the exposure levels of PCBs for local residents and e-waste workers in Guiyu, a major electronic waste scrapping center in China. The source appointment and correlation analyses showed that homologue composition of PCBs in 7 species of fish were consistent and similar to commercial PCBs Aroclor 1248. PCB levels in air surrounding the open burning site were significantly higher than those in residential area. Inhalation exposure contributed 27% and 93% to the total body loadings (the sum of dietary and inhalation exposure) of the local residents, and e-waste workers engaged in open burning respectively. Total PCB concentrations in human milk ranged from N.D. to 57.6 ng/g lipid, with an average of 9.50 ng/g lipid. The present results indicated that commercial PCBs derived from e-waste recycling are major sources of PCBs accumulating in different environmental media, leading to the accumulation of high chlorinated biphenyls in human beings.