A Comparison of Trace Gases and Particulate Matter over Beijing (China) and Delhi (India)

Air pollution represents a significant fraction of the total mortality estimated by the World Health Organization (WHO) global burden of disease projec?t (GBD). The present paper discusses the characteristics of trace gases (O₃, NO, NO₂, and CO) and particulate matter (PM₁₀ and PM_2.5) in two Asian megacities, Delhi (India) and Beijing (China). A continuous measurement of trace gases and particulate matter are considered from 12 measuring sites in Beijing and 8 sites in Delhi. Over Beijing, the annual average of PM_2.5, PM₁₀, O₃, NO₂, and CO is, respectively, 85.3, 112.8, 58.7, and 53.4 μg/m³ and 1.4 mg/m³, and, respectively, over Delhi 146.5, 264.3, 24.7,and 19.8 μg/m³ and 1.73 mg/m³. From the spatial variations of pollutants, the concentrations of particulate matter and trace gases are observed to be much higher in the urban areas compared to the suburban areas. The higher average concentrations of PM₁₀ and PM_2.5 over Delhi and Beijing are observed during winter season compared with other seasons. The maximum diurnal variation of PM₁₀ concentration is observed during winter season over Beijing and Delhi. The comparison of trace gases shows that the O₃ concentrations during daytime are obviously higher compared with nighttime, and the highest diurnal variation of O₃ is observed during summer. The concentrations of CO are highest during winter season, and higher concentrations are observed during nighttime compared to daytime. The O₃ and CO show negative correlation over Beijing and Delhi. The negative correlation between O₃ and NO₂ is merely observed over Beijing, while CO and NO₂ concentrations, in contrast, show positive correlation over Beijing.     

Concentration and Sources of PM10 and its Constituents in Alsasua, Spain

Ambient concentrations of PM₁₀ were measured every fifteen minutes from November 2002 to October 2003 at Alsasua (Northern Spain) using a laser particle counter. A high volume sampler was also used to collect 24-h integrated PM₁₀ samples at a frequency of three running days per week (i.e. three consecutive PM₁₀ samples followed by five days without sampling) for gravimetric determination of PM₁₀ mass concentrations followed by chemical analysis of its chemical components. The annual mean PM₁₀ concentration obtained using the laser particle counter with gravimetric correction was 22.7 μg m^?3 (365 days), while the mean for the gravimetric samples was 29.5 μg m^?3 (134 days). A total of 94 integrated PM₁₀ samples were analyzed for 60 chemical species using a combination of inductively coupled plasma spectrometry (ICP) and ion chromatography (IC). The concentrations of the main PM₁₀ components were found to be generally in agreement with the values reported for other Spanish cities. Bilinear Positive Matrix Factorization (PMF2) was used to study the sources of PM₁₀ and its constituents. Six main sources of PM₁₀ were identified (average contribution to total PM₁₀ mass in parentheses): crustal material (35%), secondary sulfate (21%), secondary nitrate (14%), motor vehicles (12%), sea-salt aerosol (12%) and metallurgical industries (3%).     

Influence of the 23 October 2002 Dust Storm on the Air Quality of Four Australian Cities

Widespread drought and record maximum temperatures in eastern Australia produced a large dust storm on 23 October, 2002 which traversed a large proportion of eastern Australia and engulfed communities along a 2000 km stretch of coastline from south of Sydney (NSW) to north of Mackay (Queensland). This event provided an opportunity for a study of the impacts of rural dust upon the air quality of four Australian cities. A simple model is used to predict dust concentrations, dust deposition rates and particle size characteristics of the airborne dust in the cities. The total dust load of the plume was 3.35 to 4.85 million tones, and assuming a (conservative) plume height of 1500 m, 62–90% of this dust load was deposited in-transit to the coast. It is conservatively estimated that 3.5, 12.0, 2.1 and 1.7 kilotonnes of dust were deposited during the event in Sydney, Brisbane, Gladstone and Mackay, respectively. In the South East Queensland region, this deposition is equivalent to 40% of the total annual TSP emissions for the region. The event increased TSP, PM₁₀ and PM_2.5 concentrations and reduced the visibility beyond the health and amenity guidelines in the four cities. For example, the 24-h average PM₁₀ concentrations in Brisbane and Mackay, were 161 and 475 μg m^?3 respectively, compared with the Australian national ambient air quality standard of 50 μg m^?3. The 24-h average PM_2.5 concentration in Brisbane was 42 μg m^?3, compared with the national advisory standard of 25 μg m^?3. These rural dusts significantly increased PM₁₀/TSP ratios and decreased PM_2.5/PM₁₀ ratios, indicating that most of the particles were between PM_2.5 and PM₁₀.     

A Study of Airborne Selected Metals and Particle Size Distribution in Relation to Climatic Variables and their Source Identification

Ten selected metals (Na, K, Fe, Zn, Pb, Mn, Cr, Co, Ni & Cd) were estimated in total suspended particulate (TSP) samples collected on glass fibre filters in urban Islamabad, Pakistan, from October 2002 to May 2003, using a high volume sampling technique. The wet digestion method (HNO₃/HClO₄) was used for metal analysis by the flame atomic absorption spectrophotometry (FAAS) method. Maximum mean contribution was noted for Na (1.949 μg m^?3), followed by K (0.900 μg m^?3), Zn (0.603 μg m^?3), Fe (0.584 μg m^?3) and Pb (0.214 μg m^?3). The particle size determination on % volume basis for four fractions (PM_{< 2.5}, PM_2.5–10, PM_10–100& PM_{> 100}) was also carried out. PM_10–100 were found to be the most abundant in the local atmosphere followed by PM_2.5–10, while the respirable fraction (PM_{< 2.5}) and giant fraction (PM_{> 100}) showed comparable and lower levels. The trace metals were found to be mainly associated with PM_{< 2.5} and PM_2.5–10. The influence of climatic variables on toxic trace metals and particle size fractions was also investigated statistically and it was revealed that temperature has a significant correlation with fine particle fractions and airborne trace metal levels. The source identification was carried out by Principal Component Analysis and Cluster Analysis. Four metal sources were identified: industrial (32.6%), soil-derived dust (21.9%), traffic/road dust (19.8%), and metallurgical/garbage incineration (12.4%). The metal levels were also compared with those reported for other parts around the world.     

Estimation of air quality degradation due to Saharan dust at Nouakchott, Mauritania, from horizontal visibility data

It is now irrefutable that air pollution caused by large amounts of Total Suspended Particulates (TSP) and respiratory particulates or Particulate Matter less than 10 μm in aerodynamic diameter (PM₁₀) has numerous undesired consequences on human health. Air quality degradation far from the African continent, in the US and in Europe, caused by high concentrations of African dust, is seen as a major threat even though most of these countries are very distant from the Sahara. Surprisingly, no estimates of TSP or PM₁₀ levels near the Saharan dust source are available. Based on horizontal visibility observations which are reduced by the presence of dust in the atmosphere, TSP and PM₁₀ levels are estimated throughout the year 2000 at Nouakchott-Airport, Mauritania, using relations found in the literature. It appears that concentrations of particles are significant both in terms magnitude and frequency, as the 24-hour PM₁₀ thresholds established by the US EPA National Ambient Air Quality Standards and the EU Limits Values for Air Quality were exceeded 86 and 137 times, respectively. The average annual concentration is far above air quality standards and estimated at 159 μg m^?3 for TSP and 108 μg m^?3 for PM₁₀. These very high particulate levels are likely to represent an important public health hazard and should be considered as a major environmental risk.     

PM10 and PM2.5 Levels in the Eastern Mediterranean (Akrotiri Research Station, Crete, Greece)

Particulate matter measurements (PM₁₀, PM_2.5) using a beta radiation attenuation monitor were performed at the Akrotiri research station (May 2003–March 2006) on the island of Crete (Greece). The mean PM₁₀ concentration during the measuring period (05/02/03–03/09/04) was equal to 35.0?±?17.7 μg/m³ whereas the mean PM_2.5 concentration (03/10/04–04/02/06) was equal to 25.4?±?16.5 μg/m³. The aerosol concentration at the Akrotiri station shows a large variability during the year. Mean concentrations of particulate matter undergo a seasonal change characterised by higher concentrations during summer [PM₁₀, 38.7?±?10.8 μg/m³ (2003); PM_2.5, 27.9?±?8.7 μg/m³ (2004) and 27.8?±?9.7 μg/m³ (2005)] and lower concentrations during winter [PM₁₀, 28.7?±?22.5 μg/m³ (2003/2004); PM_2.5, 21.0?±?13.0 μg/m³ (2004/2005) and 21.4?±?21.9 μg/m³ (2005/2006)]. Comparative measurements of the PM₁₀ concentration between the beta radiation attenuation monitor, a standardized low volume gravimetric reference sampler and a low volume sequential particulate sampler showed that PM₁₀ concentrations measured by the beta radiation attenuation monitor were higher than values given by the gravimetric samplers (mean ratio 1.17?±?0.11 and 1.21?±?0.08, respectively). Statistical and back trajectory analysis showed that elevated PM concentrations (PM₁₀, 93.8?±?49.1 μg/m³; PM_2.5: 102.9?±?59.9 μg/m³) are associated to desert dust events. In addition regional transport contributes significantly to the aerosol concentration levels whereas low aerosol concentrations were observed during storm episodes.     

Reductions of PM2.5 Air Concentrations and Possible Effects on Premature Mortality in Japan

The current study estimates premature mortality caused by long-term exposure to elevated concentrations of PM_2.5 (particulate matter with aerodynamic diameter equal to or less than 2.5 μm) in Japan from 2006 to 2009. The premature mortality is calculated based on a relative risk of 1.04 (95 % CI, 1.01–1.08) per 10 μg?m^?3 increase above the annual mean limit of 10 μg?m^?3 taken from the World Health Organization Air Quality Guidelines. The spatiotemporal variations of PM_2.5 are estimated based on the measurements of suspended particulate matter (SPM) (with aerodynamic diameter approximately less than 7.0 μm) at 1,843 monitors. The improvements of air quality in Japan by reducing the emissions of SPM from 2006 to 2009 could save 3,602 lives based on a reduction target of 10 μg?m^?3 annual mean concentration. This finding could be a tangible benefit gained by reducing the emissions of particulate matter in Japan.     

Identification of Fine Particle Sources in Mid-Atlantic US Area

The U.S. Environmental Protection Agency (EPA) designated 20 urban areas including major cities located in mid-Atlantic US area as being in non-attainment of the new national ambient air quality standards for PM_2.5 (particulate matter ≤2.5 μm in aerodynamic diameter). To support the development of effective State Implementation Plans for PM_2.5 in the non-attainment area, 24-h integrated Speciation Trends Networks data collected in the mid-Atlantic US urban area were analyzed through the application of the positive matrix factorization (PMF). A total of 117 to 235 samples and 27 to 29 chemical species collected at the four monitoring sites between 2001 and 2003 were analyzed and six to nine sources were identified. Secondary particles provided the highest contributions to PM_2.5 mass concentrations (38–50% for secondary sulfate; 9–18% for secondary nitrate). Potential source contribution function analyses show the potential source areas and pathways of secondary particles contributing to this region, especially the regional influences of the biogenic as well as anthropogenic secondary particles. Motor vehicle emissions contributed 21–33% to the PM_2.5 mass concentration. In four sites in southern New Jersey and Delaware, gasoline vehicle and diesel emissions were tentatively separated by different abundances of organic and elemental carbons. The compositional profiles for gasoline vehicle and diesel emissions are similar across this area. In addition, other combustion sources, aged sea salt, and intercontinental dust storms were identified.     

Dynamics of Atmospheric Aerosol Number Size Distributions in the Eastern Mediterranean During the ��SUB-AERO�� Project

Measurements of number size distributions of submicron aerosols have been performed at the Eastern part of Mediterranean as part of an extensive measurement campaign to study photo-oxidants and aerosols (SUB-AERO Project). The measurements were made at the Finokalia station on the island of Crete (Greece) and onboard the research vessel ??Aegaeon??. Two campaigns were performed during July 2000 and January 2001 using two scanning mobility particle sizers. The particle distributions measured in the range between 7.8 < d _p < 327 nm during the summer measurements and between 7.5 < d _p < 316 nm during the winter measurements, where d _p is the mobility particle diameter. The concentration of ultrafine particles (7.5 < d _p < 30 nm) was higher during the winter period and varied mainly between 5 × 10¹ and 2 × 10³?cm^?3 with concentration peak values for this mode exceeding 1 × 10⁴?cm^?3. During the summer campaign, an average number concentration of 1 × 10²?cm^?3 at Finokalia and about 5 × 10¹?cm^?3 aboard the ??Aegaeon?? vessel was measured. An average concentration of 1 × 10³?cm^?3 was measured for the particles in the size range between 30 and 100 nm, whereas in the size range 100?C300 nm, the measured concentration ranged between 1 × 10² and 5 × 10³?cm^?3. Diurnal patterns in number concentrations were observed in connection with the transport of air masses and local sources. During the winter period, three nucleation events were observed in connection with the appearance of a particle mode at 20 nm.     

Seasonal Evolution of Levels of Gaseous Pollutants in an Urban Area (Ciudad Real) in Central-Southern Spain: A Doas Study

Long term continuous monitoring measurements of urban atmospheric concentrations of O₃, NO₂, NO, and SO₂ were performed for the first time in Ciudad Real, a city in central-southern Spain. The measurements were carried out using the differential optical absorption spectroscopy (DOAS) technique, with a commercial system (OPSIS, Lund-Sweden), covering the summer and winter seasons (from 21st July 2000 to 23rd March 2001). Mean levels of O₃, NO₂ and SO₂ monitored during this period were: 27 μg m^?3, 50 μg m^?3 and 7 μg m^?3 respectively. The highest hourly averaged value of O₃ (160 μg m^?3) was measured during the summer period, while NO₂ was enhanced in wintertime (highest values 90 μg m^?3). In the coldest period, when central heating installations were operating, SO₂ showed maximum levels of 20 μg m^?3. The daily, weekly and seasonal analysis of the data shows that photochemical air pollution dominates in this urban atmosphere and is strongly influenced by levels of motor traffic and domestic heating system emissions. These measurements were compared with other studies in Spain and Europe. Also, the long path averaged DOAS measurements were compared with in situ observations made in Ciudad Real, from 23rd August 2000 to 25th September 2000, using a mobile air pollution control station. All gas concentrations reported in this paper are below the WHO guidelines and the different thresholds introduced by the European Environmental Legislation.     

Application of LIDAR Technique and MM5-CMAQ Modeling Approach for the Assessment of Winter PM10 Air Pollution: A Case Study in Beijing, China

This paper reports the use of LIDAR technique, vertical wind profiler (VWP) and the coupled MM5-CMAQ air quality modeling system to investigate a high PM₁₀ concentration episode occurred in Beijing, China during January 8–9, 2004. Through the regression analysis between the observed PM₁₀ concentrations and the observed extinction coefficients, the converting formulas from the LIDAR records to the PM₁₀ mass concentrations in Beijing have been found. Further, a 2-level-nested grid domain with spatial resolutions of 36 and 12 km have been designed and employed for this study, and the coupled MM5-CMAQ modeling system has then been evaluated using both the ground-level PM₁₀ observations and the vertical profiles of PM₁₀ deduced from the measured LIDAR extinction coefficients. Based on the verified modeling system, two emission scenarios were designed to quantitatively assess the trans-boundary PM₁₀ contributions from the surrounding provinces of Beijing. The results illustrated that the particulate matter buildup over the Beijing region was due to a number of factors, including pollutants brought in from its surrounding provinces by the southwest winds and the emission from local sources within Beijing. It indicates that while Beijing needs to take positive steps to reduce its own pollution emissions, much effort should also be placed on demanding more pollution reduction and better environmental performance from its surrounding provinces.     

A Study of PM2.5 and PM2.5-Associated Polycyclic Aromatic Hydrocarbons at an Urban Site in the Po Valley (Bologna, Italy)

PM_2.5 and PAHs bound to PM_2.5 were investigated in downtown Bologna, from January to June 2003, in order to determine the burden of the fine fraction in the aerosol of a typical urban environment of the Po Valley, a critical area in Northern Italy in terms of atmospheric pollution. The sampling campaign was divided into three parts: a winter sub-campaign, an intermediate campaign where PM_2.5 and PM₁₀ were simultaneously sampled and which identified PM_2.5 as the major component of PM₁₀, and a summer sub-campaign. Critical concentrations of both PM_2.5 and PAHs were observed in winter time; for example, in January 2003 the mean value for the 24-h average PM_2.5 concentration was 58 μg/m³, much higher than the annual arithmetic mean of 15 μg/m³ established by the US ambient air quality standard (NAAQS). Correspondingly, the mean value for benzo[a]pyrene (BAP) in PM_2.5 was 1.79 ng/m³, again higher than the annual mean of 1 ng/m³, required by European regulations for BAP in PM₁₀. In summer time the BAP concentration considerably decreases to 0.10 ng/m³ as the likely effect of photolysis and dilution on a higher boundary layer; PM_2.5 decreases too, but the mean concentration (22 μg/m³) is still higher than the NAAQS value. Further analysis included TEM microscopy of collected particles and correlations between PM_2.5, PAHs and gases (benzene, O₃, CO, NO₂, SO₂). All these observations identified on-road mobile sources as the main source of emissions and, in general, of the poor air quality level in the city of Bologna.     

A computed sulphur budget for the eastern Canadian provinces

Sulphur budgets for Ontario, Quebec and the Atlantic Provinces have been computed using the Long-Range Transport of Air Pollutants model (LRTAP) which has been developed within the Atmospheric Environment Service of Canada. Meteorological data from 1978 and a North American SO₂ emissions inventory for 1970–1974 form the basic model input. The S budgets for the eastern Canadian regions were computed for large-scale emission scenarios. The budget shows the trans-boundary mass transport, S deposition and S concentrations within the regions for each scenario and shows the relative contribution to the deposition in each region. For eastern Canada, the model shows an annual S transboundary input of about 2 Tg S, an emission of about 1.8 Tg S, a deposition of about 2.4 Tg S and an output of about 1.4 Tg S. For southwestern Ontario, the model shows an annual average SO₂ concentration of 25 to 30 μg m^?3 (10 ppb), an annual sulphate concentration of about 8 μg m^?3, an annual wet deposition of S of about 15 kg S ha^?1 and an annual sulphate concentration in precipitation of about 5 to 6 mg l^?1.     

An Assessment of the Mobile Source Contribution to PM10 and PM2.5 in the United States

Mobile sources are significant contributors to ambient particulate matter (PM) in the United States. As the emphasis shifts from PM₁₀ to PM_2.5, it becomes particularly important to account for the mobile source contribution to observed particulate levels since these sources may be the major contributor to the fine particle fraction. This is due to the fact that most mobile source mass emissions have an aerodynamic diameter less than 2.5 µm, while the particles of geological origin that tend to dominate the PM₁₀ fraction generally have an aerodynamic diameter greater than 2.5 µm. A common approach to assess the relative contributions of sources to observed particulate mass concentrations is the application of source apportionment methods. These methods include material balance, chemical mass balance (CMB), and multivariate receptor models. This paper describes a number recent source attribution studies performed in the United States in order to evaluate the range of the mobile source contribution to observed PM. In addition, a review of the methods used to apportion source contributions to ambient particulate loadings is presented.     

Influence of Saharan Dust Transport Events on PM2.5 Concentrations and Composition over Athens

The evaluation of the contribution of natural sources to PM₁₀ and PM_2.5 concentrations is a priority especially for the countries of European south strongly influenced by Saharan dust transport events. Daily PM_2.5 concentrations and composition were monitored at an urban site at 14 m above ground level, at the National Technical University of Athens campus from February to December 2010. The typical dust constituents Si, Al, Fe, K, Ca, Mg, and Ti were determined by wavelength dispersive X-ray fluorescence spectrometry (WDXRF). Sulfur, a tracer of anthropogenic origin and major constituent of PM_2.5, was determined by both WDXRF and ionic chromatography. The contribution of dust and sulfates in PM_2.5 was calculated from the analytical determinations. An annual mean of 20 μg/m³ was calculated from the mean daily PM_2.5 concentrations data. Twenty-two per cent of daily concentrations of PM_2.5 reached or exceeded the EU annual target concentration of 25 μg/m³. The exceedances occurred during 13 short periods of 1–4 days. Back-trajectory analysis was performed for these periods in order to identify the air masses origin. From these periods, ten periods were associated to Saharan dust transport events. The most intense dust transport event occurred between February 17th and 20th and was responsible for the highest recorded PM_2.5 concentration of 100 μg/m³ where the dust contribution in PM_2.5 reached 96 %. The other dust transport events were less intense and corresponded to less pronounced enhancements of PM_2.5 concentrations, and their contribution ranged from 15 to 39 % in PM_2.5 concentrations. Air masses originated from northwest Africa while the influence of central Sahara was quite smaller.     

A study of the gaseous and particulate pollutants in the environment of a thermal power plant project area

Observations on gaseous and particulate pollutants were undertaken at four locations in the region of a thermal power plant (TPP), which is under construction at Tuticorin, south India. The predicted concentrations Of SO₂ due to the emissions from the TPP and its possible impact on the inhabitants and climate in the downwind region were evaluated. Also, the predicted concentrations downwind of a Petrochemical Industrial Complex (PIC) located in the vicinity of the TPP were computed and compared with the measured concentrations. The predicted maximum concentration of SO₂ at 6 km downwind of TPP is about 530 μg m^?3 under most favourable wind conditions. The anticipated increase in SO₂ due to the thermal power plant under construction may therefore be substantial. The predicted concentrations Of SO₂, at a distance of 1.8 km downwind of the PIC, varied between 34 and 216 μg m^?3 for wind directions ranging from 70 to 90° and for Pasquill stability category C. The plume would be over the observational site when the wind direction is 80°. The maximum measured concentration was 23 ug m^?3. The discrepancy was due to the rapid fluctuations in the wind direction during the observational period over a wide range from 20 to 90°.     

Characterization of Elemental Species in PM2.5 Samples Collected in Four Cities of Northeast China

A monitoring program of particulate matter was conducted at eight sampling sites in four highly industrialized cities (Shenyang, Anshan, Fushun, and Jinzhou) of Liaoning Province in Northeast China to identify the major potential sources of ambient PM_2.5. A total of 814 PM_2.5 and PM_2.5–10 samples were collected between 2004 and 2005. All PM samples were collected simultaneously in four cities and analyzed gravimetrically for mass concentrations. A sum of 16 elemental species concentrations in the PM samples were determined using inductively coupled plasma atomic emission spectroscopy. Annual means of PM_2.5 concentrations ranged from 65.0 to 222.0 μg m^?3 in all the eight sampling sites, and the spatial and seasonal variations were discussed. Enrichment factors were calculated, and Cr, Cu, Zn, As, Cd, and Pb will be pollution-derived elements. Site-to-site comparisons of PM_2.5 species in each city were examined using coefficient of divergence, revealing that the two sites in each city are similar in elemental species. Principle component analysis was used for preliminary source analysis of PM_2.5. Three or four factors in each city were isolated, and similar sources (crustal source, coal combustion, vehicle exhaust, iron making, or some other metallurgical activities) were identified at four cities.     

Evaluation of Premature Mortality Caused by Exposure to PM2.5 and Ozone in East Asia: 2000, 2005, 2020

The aim of this study is to assess the premature mortality risks caused by exposure to particulate matter with aerodynamic diameter less than 2.5???m (PM_2.5) and ozone elevated concentrations for the years?2000, 2005, and 2020 in East Asia. The spatial distributions and temporal variations of PM_2.5 and ozone concentrations are simulated using the Models-3 Community Multiscale Air Quality Modeling System coupled with the Regional Emission Inventory in Asia. The premature mortality risks caused by exposure to PM_2.5 and ozone are calculated based on a relative risk (RR) value of 1.04 (95?% confidence interval (CI): 1.01?C1.08) for PM_2.5 concentrations above the annual mean limit of 10???g?m^?3 taken from the World Health Organization?CAir Quality Guideline and based on a RR value of 1.003 (95?% CI: 1.001?C1.004) for ozone concentration above 35?ppb of the SOMO35 index (the sum of ozone daily maximum 8-h mean concentrations above 35?ppb). We demonstrate one of the implications of the policy making in the area of environmental atmospheric management in East Asia by highlighting the annual premature mortalities associated with exposure to PM_2.5 concentrations that just meet an annual mean concentration of 10???g?m^?3, as well as ozone concentrations that have a daily zero SOMO35 index in vulnerable places. Our results point to a growing health risk that may endanger human life in East Asia. We find that the effect of PM_2.5 on human health is greater than the effect of ozone for the age group of 30?years and above. We estimate the corresponding premature mortality due to the effects of both ozone and PM_2.5 in East Asia for the years?2000 and 2005 to be around 316,000 and 520,000 cases, respectively. For future scenarios of the year?2020, policy succeed case, reference, and policy failed case, the estimated annual premature mortality rates are 451,000, 649,000, and 1,035,000 respectively.     

PM10-bound Polycyclic Aromatic Hydrocarbons (PAHs) and Cancer Risk Estimation in the Atmosphere Surrounding an Industrial Area of Shanghai, China

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in the urban atmosphere. In particular, atmospheric pollution has increasingly become severe in China due to its rapid urbanization and industrialization. In recent years, a few studies have presented information about POPs (such as PAHs, PCBs, OCPs) in aerosols at a molecular level in a limited number of cities such as Beijing, Qingdao and Guangzhou, as well as Hong Kong. Whereas, these cities are located in northern and southern China, respectively, where characteristics of atmospheric pollution might be different from those in the eastern cities, such as Shanghai. Atmospheric particle pollution is a persistent problem in Shanghai, a typical metropolis of China, which has several huge industrial regions. In order to gain a comprehensive understanding of the present state, properties and sources of PAHs pollution in Shanghai, PM₁₀ samples were collected at Coal-Fired Power Plant (CFP), Chlor-Alkali Chemical factory (CAC) and Coking and Chemical factory (CCF) in an industrial area, during the period, November 2004–September 2005. The concentrations of 16 PAHs were analyzed using the HPLC with UV visible detector. The results showed that the mean value of total PAHs in the industrial area was 64.85 ng m^?3; 3-ring PAHs were found at low levels, while 4-, 5- and 6-ring PAHs were found at high levels. The levels of BaP were 3.07 and 7.16 ng m^?3 at Chlor-Alkali Chemistry Factory and Coking and Chemistry Factory sites, respectively. PAHs levels exhibited distinct seasonal variation, with the highest level in autumn and the lowest in summer. The major source of PAHs at the industrial area was fossil fuel combustion, coal-burning, industrial furnaces including others. There was a very significant correlation of PAHs levels between CCF and CAC (R ²?=?0.91). The average concentration of BaP in the industrial area during the sampling period was 5.95 ng m^?3. It could be concluded the local population appears to be exposed to significantly high cancer risk (exceeding 2 ng m^?3 in autumn and winter) as compared to the population of other areas.     

Background pollution in the Arctic air mass and its relevance to North American acid rain studies

The Arctic air mass is a unique meteorological feature of the northern hemispheric atmosphere. Possessing well-defined meteorological characteristics, it occupies not only the polar region but also a large fraction of the Canadian and Eurasian land masses during the period November to April. Poor pollutant removal by precipitation and dry deposition within the air mass and a strong transport pathway between Eurasian mid-latitudinal sources and the north, result in elevated levels of acidic anthropogenic aerosols and gases in the air mass during winter. In summer, weak north/south transport and strong pollutant removal between the Arctic and mid-latitudes and within the Arctic, results in lower airborne concentrations of acidic pollutants. Due to the presence of the relatively polluted Arctic air mass, ‘background’ air concentrations of SO₄ ⁼, SO₂ and total NO₃ ^? are elevated in western Canada during winter. Typical mean monthly concentrations from December to March are 0.8 to 2.1, 1.0 to 2.4 and 0.1 ? 0.6 μg m^?3, respectively. In the absence of the neutralizing influence of alkaline soil dust, the acidity of snow forming in western Canada during winter is expected to range from 5 to 20 μeq l ^?1.