Polycyclic aromatic hydrocarbons in bulk PM2.5 and size-segregated aerosol particle samples measured in an urban environment

To analyze polycyclic aromatic hydrocarbons (PAHs) at an urban site in Seoul, South Korea, 24-hr ambient air PM_2.5 samples were collected during five intensive sampling periods between November 1998 and December 1999. To determine the PAH size distribution, 3-day size-segregated aerosol samples were also collected in December 1999. Concentrations of the 16 PAHs in the PM_2.5 particles ranged from 3.9 to 119.9 ng m⁻³ with a mean of 24.3 ng m⁻³.An exceptionally high concentration of PAHs(∼120 ng m⁻³) observed during a haze event in December 1999 was likely influenced more by diesel vehicle exhaust than by gasoline exhaust, as well as air stagnation, as evidenced by the low carbon monoxide/elemental carbon (CO/EC) ratio of 205 found in this study and results reported by previous studies. The total PAHs associated with the size-segregated particles showed unimodal distributions. Compared to the unimodal size distributions of PAHs with modal peaks at < 0.12 μm measured in highway tunnels in Los Angeles (Venkataraman and Friedlander, 1994), four- to six-ring PAHs in our study had unimodal size distributions, peaking at the larger size range of 0.28–0.53 μm, suggesting the coagulation of freshly emitted ultrafine particles during transport to the sampling site. Further, the fraction of PAHs associated with coarse particles(> 1.8 μm) increased as the molecular weight of the PAHs decreased due to volatilization of fine particles followed by condensation onto coarse particles.     

Gas chromatographic fingerprinting of crude oil from Idu-Ekpeye oil spillage site in Niger-delta, Nigeria

Samples were collected from an oil polluted site in Niger-delta, Nigeria. Gas chromatographic analyses carried out on the samples revealed an abundance of n-alkanes within the n-C₈–n-C₂₃ region. The pristane/phytane ratio of 5.70 obtained for the samples depicted a plant/terrestrial source input and a possible oxic depositional environment. The n-C₁₇/pristane and n-C₁₈/phytane ratios of 2.80 and 2.77, respectively, suggested that the spilled oil was only slightly weathered, as corroborated by the presence of peaks in the aromatic hydrocarbon fingerprints. The polycyclic aromatic hydrocarbon (PAH) fractions showed that the hydrocarbon fractions might have undergone combustion and/or that there was bush burning at the site prior to the oil spill incidence. This is supported by the abundance of high-molecular-weight PAHs which are pyrogenic in nature. High molecular weight PAHs are products of the combustion of petroleum or its products. The phenanthrene/anthracene ratio of 0.95, fluorathene/pyrene ratio of 2.23 and the ∑ (other three to six ringed PAHs)/∑ (five alkylated PAHs) ratio far greater than unity (4.10) also affirm this. On the other hand, the benzo (a) anthracene to chrysene ratio of 0.24 confirms the petrogenic origin of the spilled oil because chrysene which is highly abundant is a fossil PAH.     

Analysis of Polycyclic Aromatic Hydrocarbons in Street Soil Dust in Kumasi Metropolis of Ghana

Concentrations of polycyclic aromatic hydrocarbons (PAHs) in street soil dust from streets in Kumasi Metropolis in the Ashanti Region of the Republic of Ghana have been measured in this study. The concentrations of the various types of PAHs identified in this study are as follows: Naphthalene (m/e 128) – 41,700 μg/kg, Acenaphthylene (m/e 152) – 99,300 μg/kg, Acenaphthene (m/e 154) – 111,200 μg/kg, Fluorene (m/e 166) – 8,900 μg/kg, Carbazole (m/e 167) – 3,500 μg/kg, phenathrene (m/e 178) – 12,900 μg/kg, Anthracene (m/e 178) – 5,400 μg/kg, Fluoranthene (m/e 202) – 16,200 μg/kg, Pyrene (m/e 202) – 15,000 μg/kg, Benzo[a]anthracene (m/e 228) – 13,800 μg/kg, Chrysene (m/e 228) – 33,600 μg/kg, Benzo[k]fluoranthene (m/e 252) – 45,700 μg/kg, Benzo[a]pyrene (m/e 252) – 27,900 μg/kg, Perylene (m/e 252) – 57,200 μg/kg and Benzo[g, h, i]perylene (m/e 276) – 47,000 μg/kg. The results of the study shows that road users, like resident living in buildings within these areas, those engaged in commercial activities like hawking, and the general public are at risk of exposure to the toxic effects of the various types of PAHs from the exhaust of vehicles into the environment. According to these results, there is the potential for exposure to high levels of PAHs for road users and those living in urban environments or along highways.     

Cyanobacterial Flora from Polluted Marine Shores

Citation of cyanobacterial cultures from the shores of south west coast of Gujarat, India and their relationship with sea water quality, influenced by extensive pollutant runoff is reported in this study. Intensity of pollution was evaluated by physico-chemical analysis of water. Higher load of suspended solids (60–1000 mg l⁻¹) and nutrients (PO₄ ⁻P: 1.3–4 μmole l⁻¹ and NO₃ ⁻N: 12.5–17.8 μmole l⁻¹) were persistent throughout the analysis. Community structure is seen to be influenced by such persistent pollution. Twenty nine cyanobacterial species were isolated belonging to 9 genera of 4 families, with an elevated occurrence of Oscillatoria and Lyngbya species. No heterocystous cyanobacteria were isolated throughout the study.     

Chemical Compositions and Sources of Organic Matter in Fine Particles of Soils and Sands from the Vicinity of Kuwait City

Fine particles in the atmosphere from soil and sand resuspension contain a variety of organic compounds from natural biogenic and anthropogenic matter. Soil and sand samples from various sites near Kuwait city were collected, sieved to retain the fine particles, and extracted with a mixture of dichloromethane and methanol. The extracts were derivatized and analyzed by gas chromatography-mass spectrometry in order to characterize the chemical compositions and sources of the organic components. The major inputs of organic compounds were from both natural biogenic and anthropogenic sources in these samples. Vegetation was the major natural source of organic compounds and included n-alkanols, n-alkanoic acids, n-alkanes, sterols and triterpenoids. Saccharides had high concentrations (31–43%) in the sand dune and seafront samples, indicating sources from decomposed vegation materials and/or the presence of viable microbiota such as bacteria and fungi. Vehicular emission products, leakage of lubricating oils, discarded plastics and emissions from cooking operations were the major anthropogenic inputs in the samples from the urban areas. This input was mainly UCM, n-alkanes, hopanes, plasticizers and cholesterol, respectively.     

Levels of PAHs in the soils of Belgrade and its environs

Polycyclic aromatic hydrocarbons (PAHs) were analysed in 39 soil samples (0–10 cm upper layer) collected in Belgrade, the capital of Serbia. The sampling sites were randomly selected from urban, urban/recreational and rural areas; the samples were collected in April and December 2003 and July and October 2004. The sum of the 16 PAHs corresponding to the recreational zone (298 μg/kg) was close to the urban zone (375 μg/kg). Mean soil ΣPAH concentration from rural areas was 18 μg/kg dry weight. Comparing to values observed in the urbanized locations around the world, the overall levels of PAHs in this study are low. The PAH ratios obtained pointed to a domination of pyrogenically formed PAHs in the examined soils. The dominant PAHs in soil samples in urban zones were fluoranthene, benz[a]anthracene, phenanthrene and pyrene, mostly emitted from noncatalyst vehicles which are still in use in Serbia. The total carcinogenic potency for each sampling site was calculated. Regardless of the used carcinogenic activity factors, carcinogenic potency of 7 sites were 3–9 times higher than the reference ones indicating the increased carcinogenic burden of soils from these sites.     

Assessment and Treatment of Hydrocarbon Inundated Soils Using Inorganic Nutrient (N-P-K) Supplements: II. A Case Study of Eneka Oil Spillage in Niger Delta, Nigeria

Polluted soils from Eneka oil field in the Niger delta region of Nigeria were collected two months after recorded incidence of oil spillage as part of a two-site reclamation programme. The soils were taken on the second day of reconnaissance from three replicate quadrats, at surface (0–15 cm) and subsurface (15–30 cm) depths, using the grid sampling technique. Total extractable hydrocarbon content (THC) of the polluted soils ranged from 1.006×10³–5.540× 10⁴ mg/kg at surface and subsurface depths (no overlap in Standard Errors at 95% Confidence Level). Greenhouse trials for possible reclamation were later carried out using (NH₄)₂SO₄, KH₂PO₄ and KCl (N-P-K) fertilizer as nutrient supplements. Nitrogen as NO₃-N and potassium were optimally enhanced at 2% (w/w) and 3% (w/w) of the N-P-K supplementation respectively. Phosphorus, which was inherently more enhanced in the soils than the other nutrients, maintained same level impact after 20 g treatment with the N-P-K fertilizer. Total organic carbon (%TOC), total organic matter (%TOM), pH and % moisture content all provided evidence of enhanced mineralization in the fertilizer treated soils. If reclamation of the crude oil inundated soils is construed as the return to normal levels of metabolic activities of the soils, then the application of the inorganic fertilizers at such prescribed levels would duly accelerate the remediation process. This would be, however, limited to levels of pollution empirically defined by such THC values obtained in this study. The data on the molecular compositional changes of the total petroleum hydrocarbon content (TPH) of the spilled-oil showed the depletion of the fingerprints of the n-paraffins, nC₈–nC₁₀, and complete disappearance of C₁₂–C₁₇ as well as the acyclic isoprenoid, pristane, all of which provided substantial evidence of degradation.     

Rinodina sophodes (Ach.) Massal.: a bioaccumulator of polycyclic aromatic hydrocarbons (PAHs) in Kanpur City, India

The aim of this study is to determine the possibility of using Rinodina sophodes (Ach.) Massal., a crustose lichen as polycyclic aromatic hydrocarbons (PAHs) bioaccumulator for evaluation of atmospheric pollution in tropical areas of India, where few species of lichens are able to grow. PAHs were identified, quantified and compared to evaluate the potential utility of R. sophodes. The limit of detection for different PAHs was found to be 0.008–0.050 μg g^− 1. The total PAHs in different sites were ranged between 0.189 ± 0.029 and 0.494 ± 0.105 μg g^− 1. The major sources of PAHs were combustion of organic materials, traffic and vehicular exhaust (diesel and gasoline engine). Significantly higher concentration of acenaphthylene and phenanthrene indicates road traffic as major source of PAH pollution in the city. Two-way ANOVA also confirms that all PAHs content showed significant differences between all sampling sites (P 1%). This study establishes the utility of R. sophodes in monitoring the PAHs accumulation potentiality for development of effective tool and explores the most potential traits resistant to the hazardous environmental conditions in the tropical regions of north India, where no such other effective way of biomonitoring is known so far.     

Spatial and Temporal Variations in Trace Metal Concentrations in the Cockle, Austrovenus Stutchburyi from Otago, New Zealand

This is the first comprehensive study of sources of variation in metal concentrations within the whole tissues of a shallow burrowing, filter-feeding intertidal clam, Austrovenus stutchburyi. Samples were collected from 12 sites in April, August, November and February in 1993–1994 in the vicinity of Otago Harbour and Peninsula, New Zealand. Total tissue trace metal concentrations (μg g⁻¹ dry weight) were measured in individual animals for the essential metals : Mn, Cu, Zn, Ni and the non-essential Cr using trace-metal clean acid-digestion and ICP-OAES techniques. Average metal concentrations were 3–60 μg g⁻¹ for Cu, 40–118 μg g⁻¹ for Zn, 2–12 μg g⁻¹ for Mn, 5–35 μg g⁻¹ for Ni and 1–44 μg g⁻¹ for Cr. These levels decreased with body weight and differed amongst sites except for Cr in February (mid-summer). Highest concentrations occurred at sites close to a city (Dunedin) and within the central harbour region although the Cu, Zn, Ni and Cr concentrations did not correlate with the environmental gradient or season. At one coastal site, samples of both the blue mussel Mytilus galloprovincialis and cockles gave similar trends in trace metal levels. These results suggest that the cockle could be a useful trace metal biomonitor within NZ estuaries.     

Ambient Aerosol and its Carbon Content in Gainesville, a Mid-Scale City in Florida

Ambient aerosols were collected during 2000–2001 in Gainesville, Florida, using a micro-orifice uniform deposit impactor (MOUDI) to study mass size distribution and carbon composition. A bimodal mass distribution was found in every sample with major peaks for aerosols ranging from 0.32 to 0.56 μm, and 3.2 to 5.6 μm in diameter. The two distributions represent the fine mode (<2.5 μm) and the coarse mode (>2.5 μm) of particle size. Averaged over all sites and seasons, coarse particles consisted of 15% carbon while fine particles consisted of 22% carbon. Considerable variation was noted between winter and summer seasons. Smoke from fireplaces in winter appeared to be an important factor for the carbon, especially the elemental carbon contribution. In summer, organic carbon was more abundant. The maximum secondary organic carbon was also found in this season (7.0 μg m⁻³), and the concentration is between those observed in urban areas (15–20 μg m⁻³) and in rural areas (4–5 μg m⁻³). However, unlike in large cities where photochemical activity of anthropogenic emissions are determinants of carbon composition, biogenic sources were likely the key factor in Gainesville. Other critical factors that affect the distribution, shape and concentration were precipitation, brushfire and wind.     

Lead and cadmium concentrations in shorebirds from the Yeongjong Island, Korea

This study presents concentration levels of pollutants (lead, and cadmium) in tissues (livers, kidneys, muscles, and bones) of shorebirds (Kentish Plovers (n = 5), Mongolian Plovers (n = 2), Dunlins (n = 6), Great Knots (n = 10), Terek Sandpipers (n = 10)) from Yeongjong Island, Korea in the East Asian–Australian migration flyways during the autumn migration in 1994–1995. Lead concentrations in livers, in kidneys, in muscles, and in bones were significantly different among shorebird species. Lead concentrations in livers of Kentish Plovers (4.76 ± 2.72 μg/wet g), Mongolian Plovers (2.05 μg/wet g), Dunlins (3.77 ± 1.07 μg/wet g), and Great Knots (4.27 ± 3.19 μg/wet g) were less than the toxic level, and lead concentrations in livers of Terek Sandpipers (1.20 ± 0.94 μg/wet g) were at the background level. Cadmium concentrations in livers, in kidneys, in muscles, and in bones did not vary among shorebirds, and concentrations of cadmium in livers and in kidneys were at background level (respectively, approximate 1 μg/wet g, approximate 2.67 μg/wet g) in all shorebird species. We suggest that interspecific differences of lead and cadmium concentrations were attributed to differences in exposure time and differences of diet, microhabitats in wintering ground. In livers and kidney of shorebirds from Yeongjong Island, lead and cadmium concentrations were higher than other locations previously reported.     

The effect of temperature on PAHs emission from incineration of acrylic waste

Incineration of acrylic waste solution in a lab scale quartz tube vertical incinerator showed the presence of 12–15 polycyclic aromatic hydrocarbons (PAHs) from a list of 16 priority pollutants at 700–1100^˚C after an interval of 50^˚C. The amount of total 16 PAHs at 900 and 1100^˚C was about 8.5 and 1.25 times higher than those at 700^˚C (739.48 μg g⁻¹) respectively. The amount of total probable (2A) and possible (2B) human carcinogenic PAHs was minimum at 700^˚C.     

Heavy metals and PCDD/Fs in solid waste incinerator fly ash in Zhejiang province,China: chemical and bio-analytical characterization

Fly ash samples were taken from solid waste incinerators with different feeding waste, furnace type, and air pollution control device in six cities of Zhejiang province. The solid waste incinerators there constitute one fifth of incinerators in China. Heavy metals and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analyzed in the fly ash. Moreover, the fly ash samples were extracted by toxicity characteristic leaching procedure (TCLP). The biotoxicity of the leachate was evaluated by Chlorella pyrenoidosa. High variation and contents were found for both the heavy metals and PCDD/Fs. The contents of Zn, Cu, As, Pb, Cd, Cr, Ni, and Hg in the fly ash samples varied from 300 to 32,100, 62.1–1175, 1.1–57, 61.6–620, 0.4–223, 16.6–4380, 1.2–94.7, and 0.03–1.4 μg g⁻¹ dw, respectively. The total contents of 17 PCDD/Fs varied from 0.1128 to 127.7939 μg g⁻¹ dw, and the 2,3,7,8-TeCDD toxic equivalents (TEQ) of PCDD/Fs ranged from 0.009 to 6.177 μg g⁻¹ dw. PCDF congeners were the main contributor to the TEQ. The leachate of the fly ash showed biotoxicity to C. pyrenoidosa. A significant correlation was found between the Cd and EC₅₀ values. Further research is required to investigate the environmental impact of the various pollutants in the fly ash.     

PAHs Contamination in Bank Sediment of the Yamuna River, Delhi, India

This study was performed to elucidate the distribution, concentration trend and possible sources of PAHs in bank sediment of river Yamuna in Delhi, India. The levels of 16 priority polycyclic aromatic hydrocarbons (PAHs) were analyzed during pre-monsoon, monsoon and post-monsoon seasons in the sediment fraction < 53 μm. Reference standards and internal standards were used for identification and quantification of PAHs by HPLC. The sum of 16 PAH compounds ranged from 4.50 to 23.53 μg/g with a mean concentration of 10.15 ± 4.32 μg/g (dry wt.). Among 5 sites studied, the site, Income Tax Office (ITO) was found to be the hotspot attaining highest concentration. Predominance of 2–4 ring PAHs suggests a relatively recent local sources of PAHs in the study area. Moreover, molecular indices based source apportionment also illustrates pyrogenic source fingerprint of PAHs. No significant temporal trend was observed.     

Trace Metal Levels in Mussels (Mytilus Galloprovincialis L. 1758) from Turkish Aegean Sea Coast

Bio-monitoring of some heavy metal levels (Cd, Pb, Zn, Cu) in whole edible soft parts of Mytilus galloprovincialis (L. 1758) was conducted in Turkish Aegean Sea coast during the period of September 2002–August 2003 seasonally. Moreover, some physico-chemical environmental parameters, also have been analysed in the same region. The values of some physico-chemical environmental parameters in coastal waters of Turkish Aegean Sea were changed between; 9.0–27.0 ^∘C for temperature, 31.93–40.45 psu for salinity, 7.35–8.48 for pH and 4.05–9.50 mg/l for dissolved oxygen. The levels of trace elements in whole edible soft parts including interstitial fluids of Mediterranean mussels M. galloprovincialis (L. 1758), sampled from 6 different regions of Turkish Aegean Sea coast have ranged between; 0.04–0.52 μg Cd/g wet weight, 0.49–1.72 μg Pb/g w.w., 0.95–1.85 Cu/g w.w., 16.11–37.15 μg Zn/g w.w. The highest values for all trace metals (Cd, Pb, Zn, Cu) were measured in inner part of Izmir Bay (station 3) and lowest in Sigacik and Gulluk Bay (station 5, 6). Generally heavy metal levels are lower than the results in soft mussel tissues reported from Mediterranean regions.     

Comparative Metal Distribution in Hair of Pakistani and Libyan Population and Source Identification by Multivariate Analysis

Using nitric acid-perchloric acid wet digestion based FAAS method ten selected metals (Cd, Co, Cr, Fe, K, Mn, Na, Ni, Pb and Zn) were determined in the scalp hair of male Pakistani and Libyan donors (n = 62), between 3–54 years age and residing in typical urban areas. The study was taken up to identify sources of metal distribution in two diverse population segments exposed to different environments. Sodium emerged with the highest mean hair concentration of 511.0 μg/g and 496.9 μg/g for Libyan and Pakistani donors respectively, followed by K, at 266.2 μg/g and 242.4 μg/g for the two donor categories. Cadmium showed the lowest mean hair concentration for both Pakistani (0.380 μg/g) and Libyan (0.530 μg/g) donors. Levels of Na, K, Pb, Cr and Cd were higher in hair of Libyan donors compared with Pakistani counterparts which showed higher comparative levels of Zn, Fe, Co, Ni and Mn. Strong metal-to-metal correlations were found between Na–K (r = 0.638) and Cd–Co (r = 0.574) for Pakistani donors, while for Libyan donors, Na–K (r = 0.680) and Fe–Mn (r = 0.624) correlations emerged as strongly significant. Only K was found to have a strong positive correlation (r = 0.611) with age for Pakistani donors while this correlation was significantly negative (r = −0.500) for Libyan donors, probably arising from individual food habits. Other metals showed no viable relationship with age. Principal Component Analysis (PCA) and Cluster Analysis (CA) of the data evidenced food, industrial emissions and automobile emissions as possible sources of metal distribution. The results of the present study are compared with those reported for subjects from other regions of the world.     

Organochlorine pesticides and polychlorinated biphenyl residues in reared and wild Dicentrarchus labrax from the Mediterranean Sea (Sicily, Italy)

The aim of this research was to compare the levels of organochlorine pesticides and PCBs in samples of Dicentrarchus labrax living in the Straits of Messina with samples cultivated in cages in the Mediterranean Sea. Muscles and liver tissues sampled over the months, within the same year, were analyzed. The quantitative determination of the organochlorine compounds was performed by GC-ECD and confirmed with GC–MS. The results showed that the concentrations of DDTs in muscles and livers as such of reared sea bass were in the range 0.2–1.3 μg/kg and 9.6 –48.4 μg/kg, respectively. In wild fish the concentrations of DDTs were very much lower: 0.1 μg/kg in muscles, 5.1–9.0 μg/kg in livers. Total PCBs levels were higher in cultivated sea bass than in wild fish; the concentration ranges were 5.3–59.7 μg/kg and 74.4–267.4 μg/kg in muscle and liver of reared samples, respectively, and 1.1–1.5 μg/kg and 63.2–109.4 μg/kg in muscle and liver of wild samples, respectively.     

Receptor modeling for source apportionment of polycyclic aromatic hydrocarbons in urban atmosphere

This study reports source apportionment of polycyclic aromatic hydrocarbons (PAHs) in particulate depositions on vegetation foliages near highway in the urban environment of Lucknow city (India) using the principal components analysis/absolute principal components scores (PCA/APCS) receptor modeling approach. The multivariate method enables identification of major PAHs sources along with their quantitative contributions with respect to individual PAH. The PCA identified three major sources of PAHs viz. combustion, vehicular emissions, and diesel based activities. The PCA/APCS receptor modeling approach revealed that the combustion sources (natural gas, wood, coal/coke, biomass) contributed 19–97% of various PAHs, vehicular emissions 0–70%, diesel based sources 0–81% and other miscellaneous sources 0–20% of different PAHs. The contributions of major pyrolytic and petrogenic sources to the total PAHs were 56 and 42%, respectively. Further, the combustion related sources contribute major fraction of the carcinogenic PAHs in the study area. High correlation coefficient (R ² > 0.75 for most PAHs) between the measured and predicted concentrations of PAHs suggests for the applicability of the PCA/APCS receptor modeling approach for estimation of source contribution to the PAHs in particulates.     

Facile and Sensitive Spectrophotometric Determination of Carbosulfan in Formulations and Environmental Samples

Facile, selective and sensitive spectrophotometric method has been developed for the determination of carbosulfan in insecticidal formulations, fortified water, food grains, agriculture wastewater and soil samples with newly synthesized reagents. The method was based on acid and alkaline hydrolysis of the carbosulfan pesticide, and the resultant hydrolysis product of carbosulfan was coupled with 2,6-dibromo-4-methylaniline to give a yellow color product with λ _max of 464 nm or interaction with 2,6-dibromo-4-nitroaniline to produce yellow colored product with λ _max of 408 nm or coupling with 2,4,6-tribromoaniline to form red colored product has a λ _max of 471 nm. Under optimal conditions, Beer’s law range for 2,6-dibromo-4-methylaniline (DBMA) was found to be 0.2–12.0 μg ml⁻¹, 0.6–16.0 μg ml⁻¹ for 2,6-dibromo-4-nitroaniline (DBNA) and 0.4–15.0 μg ml⁻¹ for 2,4,6-tribromoaniline (TBA). The molar absorptivity of the color systems were found to be 3.112 × 10⁴ l mol⁻¹ cm⁻¹ for DBMA, 3.214 × 10⁴ l mol⁻¹ cm⁻¹ for DBNA and 3.881 × 10⁴ l mol⁻¹ cm⁻¹ for TBA. Sandell’s of the color reactions are 0.013 μg cm⁻² (DBMA), 0.012 μg cm⁻² (DBNA) and 0.011 μg cm⁻² (TBA) respectively. The effect of the non-target species on the determination of carbosulfan was studied to enhance the selectivity of the proposed methods. The formation of colored derivatives with the coupling agents is instantaneous and stable for 28, 30, and 26 h. Performance of the proposed methods were compared statistically in terms Student’s F and t-tests with the reported methods. An erratum to this article can be found at     

Evaluation of A Sampling Strategy for Estimation of Long-term Pm2.5 Exposure for Epidemiological Studies

As part of the European Community Respiratory Health Survey (ECRHS) PM_2.5 (particles collected with an upper 50% cut point of 2.5 μm aerodynamic diameter) was measured using an EPA-WINS (Environmetal Protection Agency Well Impactor Ninety-six) sampler. The monitoring schedule was restricted to 7 days per month for one year. Simultaneously, during this one year study period a collocated Harvard Impactor (HI) was run on a daily basis in Erfurt, Germany. Here we validated the reliability of annual, seasonal and monthly means estimated using the ECRHS scheme (measurements taken less than 25% of the whole study period) with the ‘true’ long-term averages, which were estimated using all available daily means.The daily PM_2.5 means, obtained by both instruments operated in parallel, were only slightly different (the mean difference between EPA-WINS and HI was 1.8 μg m⁻³ and 2.8 μg m⁻³ for the winter means). The values obtained by the two instruments were highly correlated (r = 0.95).In view of that negligible difference, no additional bias was seen with respect to the annual and the winter means estimated by the two different sampling strategies (the difference was 1.7 μg m⁻³ and 2.7 μg m⁻³, respectively). Monthly means, however, can only be considered to be a crude estimate that may substantially under- or overestimate the true monthly mean value.