Reducing dust exposure in indoor climbing gyms

As users of indoor climbing gyms are exposed to high concentrations (PM(10) up to 4000 μg m(-3); PM(2.5) up to 500 μg m(-3)) of hydrated magnesium carbonate hydroxide (magnesia alba), reduction strategies have to be developed. In the present paper, the influence of the use of different kinds of magnesia alba on dust concentrations is investigated. Mass concentrations, number concentrations and size distributions of particles in indoor climbing gyms were determined with an optical particle counter, a synchronized, hybrid ambient real-time particulate monitor and an electrical aerosol spectrometer. PM(10) obtained with these three different techniques generally agreed within 25%. Seven different situations of magnesia alba usage were studied under controlled climbing activities. The use of a suspension of magnesia alba in ethanol (liquid chalk) leads to similar low mass concentrations as the prohibition of magnesia alba. Thus, liquid chalk appears to be a low-budget option to reduce dust concentrations. Magnesia alba pressed into blocks, used as powder or sieved to 2-4 mm diameter, does not lead to significant reduction of the dust concentrations. The same is true for chalk balls (powder enclosed in a sack of porous mesh material). The promotion of this kind of magnesia alba as a means of exposure reduction (as seen in many climbing gyms) is not supported by our results. Particle number concentrations are not influenced by the different kinds of magnesia alba used. The particle size distributions show that the use of magnesia alba predominantly leads to emission of particles with diameters above 1 μm.     

Aerosol size distribution and mass concentration measurements in various cities of Pakistan

During March and April 2010 aerosol inventories from four large cities in Pakistan were assessed in terms of particle size distributions (N), mass (M) concentrations, and particulate matter (PM) concentrations. These M and PM concentrations were obtained for Karachi, Lahore, Rawalpindi, and Peshawar from N concentrations using a native algorithm based on the Grimm model 1.109 dust monitor. The results have confirmed high N, M and PM concentrations in all four cities. They also revealed major contributions to the aerosol concentrations from the re-suspension of road dust, from sea salt aerosols, and from vehicular and industrial emissions. During the study period the 24 hour average PM(10) concentrations for three sites in Karachi were found to be 461 μg m(-3), 270 μg m(-3), and 88 μg m(-3), while the average values for Lahore, Rawalpindi and Peshawar were 198 μg m(-3), 448 μg m(-3), and 540 μg m(-3), respectively. The corresponding 24 hour average PM(2.5) concentrations were 185 μg m(-3), 151 μg m(-3), and 60 μg m(-3) for the three sites in Karachi, and 91 μg m(-3), 140 μg m(-3), and 160 μg m(-3) for Lahore, Rawalpindi and Peshawar, respectively. The low PM(2.5)/PM(10) ratios revealed a high proportion of coarser particles, which are likely to have originated from (a) traffic, (b) other combustion sources, and (c) the re-suspension of road dust. Our calculated 24 hour averaged PM(10) and PM(2.5) concentrations at all sampling points were between 2 and 10 times higher than the maximum PM concentrations recommended by the WHO guidelines. The aerosol samples collected were analyzed for crustal elements (Al, Fe, Si, Mg, Ca) and trace elements (B, Ba, Cr, Cu, K, Na, Mn, Ni, P, Pb, S, Sr, Cd, Ti, Zn and Zr). The averaged concentrations for crustal elements ranged from 1.02 ± 0.76 μg m(-3) for Si at the Sea View location in Karachi to 74.96 ± 7.39 μg m(-3) for Ca in Rawalpindi, and averaged concentrations for trace elements varied from 7.0 ± 0.75 ng m(-3) for B from the SUPARCO location in Karachi to 17.84 ± 0.30 μg m(-3) for Na at the M. A. Jinnah Road location, also in Karachi.     

Source apportionment of PM10 and PM(2.5) at Tocopilla, Chile (22 degrees 05' S, 70 degrees 12' W)

Tocopilla is located on the coast of Northern Chile, within an arid region that extends from 30 degrees S to the border with Perú. The major industrial activities are related to the copper mining industry. A measurement campaign was conducted during March and April 2006 to determine ambient PM10 and PM(2.5) concentrations in the city. The results showed significantly higher PM10 concentrations in the southern part of the city (117 microg/m3) compared with 79 and 80 (microg/m3) in the central and northern sites. By contrast, ambient PM2.5 concentrations had a more uniform spatial distribution across the city, around 20 (microg/m3). In order to conduct a source apportionment, daily PM10 and PM(2.5) samples were analyzed for elements by XRF. EPA's Positive Matrix Factorization software was used to interpret the results of the chemical compositions. The major source contributing to PM(2.5) at sites 1, 2 and 3, respectively are: (a) sulfates, with approximately 50% of PM2.5 concentrations at the three sites; (b) fugitive emissions from fertilizer storage and handling, with 16%, 21% and 10%; (c) Coal and residual oil combustion, with 15%, 15% and 4%; (d) Sea salt, 5%, 6% and 16%; (e) Copper ore processing, 4%, 5% and 15%; and (f) a mixed dust source with 11%, 7% and 4%. Results for PM10--at sites 1, 2 and 3, respectively--show that the major contributors are: (a) sea salt source with 36%, 32% and 36% of the PM10 concentration; (b) copper processing emissions mixed with airborne soil dust with 6.6%, 11.5% and 41%; (c) sulfates with 31%, 31% and 12%; (d) a mixed dust source with 16%, 12% and 10%, and (e) the fertilizer stockpile emissions, with 11%, 14% and 2% of the PM10 concentration. The high natural background of PM10 implies that major reductions in anthropogenic emissions of PM10 and SO2 would be required to attain ambient air quality standards for PM10; those reductions would curb down ambient PM(2.5) concentrations as well.     

Airborne particulate matter and BTEX in office environments

Total suspended particulate (TSP), PM(2.5) and BTEX were collected in nine offices in the province of Antwerp, Belgium. Both indoor and outdoor aerosol samples were analysed for their weight, elemental composition, and water-soluble fraction. Indoor TSP and PM(2.5) concentrations ranged from 7-31 microg m(-3) and 5-28 microg m(-3), with an average of 18 and 11 microg m(-3), respectively. Of all the elements analysed in indoor TSP, more than 95% was represented by Al, Si, K, Ca, Fe, Cl and S, accounting for 12% of the TSP by mass. The other elements showed significant enrichment relative to the earth's crust. The water-soluble ionic fraction accounted for almost 30% of the sampled indoor TSP by weight, and was enriched by anthropogenic activities. It was shown that the indoor PM levels varied among the offices, depending on the ventilation pattern, location, and occupation density of the office. Indoor BTEX levels ranged together from 5-47 microg m(-3) and were considerably higher than the corresponding outdoor levels. It was observed that some recently constructed and renovated buildings were clearly burdened with elevated levels for toluene, ethyl benzene, and xylenes, while outdoor air was found to be the main source for BTEX levels at the 'older' offices.     

Relationship between different size classes of particulate matter and meteorology in three European cities

Evidence on the correlation between particle mass and (ultrafine) particle number concentrations is limited. Winter- and spring-time measurements of urban background air pollution were performed in Amsterdam (The Netherlands), Erfurt (Germany) and Helsinki (Finland), within the framework of the EU funded ULTRA study. Daily average concentrations of ambient particulate matter with a 50% cut off of 2.5 microm (PM2.5), total particle number concentrations and particle number concentrations in different size classes were collected at fixed monitoring sites. The aim of this paper is to assess differences in particle concentrations in several size classes across cities, the correlation between different particle fractions and to assess the differential impact of meteorological factors on their concentrations. The medians of ultrafine particle number concentrations were similar across the three cities (range 15.1 x 10(3)-18.3 x 10(3) counts cm(-3)). Within the ultrafine particle fraction, the sub fraction (10-30 nm) made a higher contribution to particle number concentrations in Erfurt than in Helsinki and Amsterdam. Larger differences across the cities were found for PM2.5(range 11-17 microg m(-3)). PM2.5 and ultrafine particle concentrations were weakly (Amsterdam, Helsinki) to moderately (Erfurt) correlated. The inconsistent correlation for PM2.5 and ultrafine particle concentrations between the three cities was partly explained by the larger impact of more local sources from the city on ultrafine particle concentrations than on PM2.5, suggesting that the upwind or downwind location of the measuring site in regard to potential particle sources has to be considered. Also, relationship with wind direction and meteorological data differed, suggesting that particle number and particle mass are two separate indicators of airborne particulate matter. Both decreased with increasing wind speed, but ultrafine particle number counts consistently decreased with increasing relative humidity, whereas PM2.5 increased with increasing barometric pressure. Within the ultrafine particle mode, nucleation mode (10-30 nm) and Aitken mode (30-100 nm) had distinctly different relationships with accumulation mode particles and weather conditions. Since the composition of these particle fractions also differs, it is of interest to test in future epidemiological studies whether they have different health effects.     

Indoor air pollution levels in public buildings in Thailand and exposure assessment

Levels of pollutants including PM2.5 and PM2.5 composition (black carbon and water soluble ions), SO(2), NO(2), CO, CO(2), and BTEX (benzene, toluene, ethylbenzene, xylene) were monitored for indoor and outdoor air at a university campus and a shopping center, both located in the Northern suburb of Bangkok. Sampling was done during December 2005-February 2006 on both weekdays and weekends. At the university, indoor monitoring was done in two different air conditioned classrooms which shows the I/O ratios for all pollutants to be below 0.5-0.8 during the weekends. However, on weekdays the ratios for CO(2) and most detected BTEX were above 1.0. The concept of classroom occupancy was defined using a function of the student number in a lecture hour and the number of lecture hours per day. Classroom 2, which had a higher occupancy than classroom 1, was characterized by higher concentrations of most pollutants. PM2.5 was an exception and was higher in classroom 1 (37 microg/m(3), weekdays) as compared to classroom 2 (26 microg/m(3), weekdays) which was likely linked to the dust resuspension from the carpeted floor in the former. Monitoring was also done in the shopping mall at three different sites. Indoor pollutants levels and the I/O ratios at the shopping mall were higher than at the university. Levels of all pollutants measured at the car park, except for toluene and CO(2), were the highest. I/O ratios of the pollutants at the mall were above 1.0, which indicates the relatively higher influence of the indoor sources. However, the black carbon content in PM2.5 outdoor is higher than indoor, which suggest the important contribution from outdoor combustion sources such as the traffic. Major sources of outdoor air pollution in the areas were briefly discussed. Exposure modeling was applied using the time activity and measured pollutant concentrations to assess the exposure of different groups of people in the study areas. High exposure to PM2.5, especially for the people working in the mall, should be of health effect concern.     

宁波和温州地区夏季大气中不同粒径颗粒物特征分析

对宁波地区北仑和奉化站、温州地区乐清站3个监测点夏季TSP、PM10、PM2.5和PM1.0进行监测,测试分析各种粒径颗粒物浓度水平和粒径分布特征,并通过化学质量平衡(CMB)受体模型对颗粒物进行源解析。监测结果显示,夏季宁波、温州地区TSP和PM10日均浓度为0.049～0.134mg/m3和0.025～0.084mg/m3,均未超过我国环境空气质量二级标准;PM2.5日均浓度为0.007～0.069mg/m3,按美国2006年EPA最新标准限值0.035mg/m3衡量,奉化、乐清、北仑站的超标天数占总监测天数的比例分别为75%、40%和37.5%。粒径分布统计结果显示,3个监测站点PM10占TSP的比例为48.78%～86.96%;PM2.5占TSP的比例为33.33%～72.46%;奉化和乐清监测点PM10中PM2.5和PM1.0的比例平均值在50%以上。源解析结果显示,夏季TSP主要来源于土壤尘,其次是建筑尘和煤烟尘,其贡献率分别为40.70%～55.49%、9.62%～13.64%和5.85%～17.28%。     

Organic dust and gaseous contaminants at wood working shops

Airborne dust bioaerosols, ammonia and formaldehyde levels were determined inside two different (ventilated and unventilated) wood working shops. Airborne dust was found at mean values of 4.3 and 3.01 mg m(-3). These levels were higher than that recommended by Egyptian environmental law [1 mg m(-3) indoor maximum allowable concentration (MAC) for hard wood]. The highest frequency of aerodynamic size distribution of airborne wood dust was detected at a diametre of 4.9 microm which was recorded during a machining operation. Total viable bacteria were recorded at a mean value of 10(4) colony-forming units (cfu) m(-3), whereas Gram-negative bacteria were found at very low counts (10(1) cfu m(-3)). Fungi levels were recorded at mean values of 10(3) and 10(2) cfu m(-3) in ventilated and unventilated shops, respectively. Penicillium, Aspergillus, Cladosporium and yeast species were dominant isolates. Moreover, actinomycetes were found at a mean value of 10(3) cfu m(-3) at both workshops. Ammonia was detected in relatively low concentrations (mean values of 457 and 623 microg m(-3)), whereas formaldehyde was found in relatively moderate concentrations (mean values of 0.42 and 0.64 ppm).     

Indoor and outdoor concentrations of fine particles, particle-bound PAHs and volatile organic compounds in Kaunas, Lithuania

This complex study presents indoor and outdoor levels of air-borne fine particles, particle-bound PAHs and VOCs at two urban locations in the city of Kaunas, Lithuania, and considers possible sources of pollution. Two sampling campaigns were performed in January-February and March-April 2009. The mean outdoor PM(2.5) concentration at Location 1 in winter was 34.5 ± 15.2 μg m(-3) while in spring it was 24.7 ± 12.2 μg m(-3); at Location 2 the corresponding values were 36.7 ± 21.7 and 22.4 ± 19.4 μg m(-3), respectively. In general there was little difference between the PM concentrations at Locations 1 and 2. PM(2.5) concentrations were lower during the spring sampling campaign. These PM concentrations were similar to those in many other European cities; however, the levels of most PAHs analysed were notably higher. The mean sum PAH concentrations at Locations 1 and 2 in the winter campaign were 75.1 ± 32.7 and 32.7 ± 11.8 ng m(-3), respectively. These differences are greater than expected from the difference in traffic intensity at the two sites, suggesting that there is another significant source of PAH emissions at Location 1 in addition to the traffic. The low observed indoor/outdoor (I/O) ratios indicate that PAH emissions at the locations studied arise primarily from outdoor sources. The buildings at both locations have old windows with wooden frames that are fairly permissive in terms of air circulation. VOC concentrations were mostly low and comparable to those reported from Sweden. The mean outdoor concentrations of VOC's were: 0.7 ± 0.2, 3.0 ± 0.8, 0.5 ± 0.2, 3.5 ± 0.3, and 0.2 ± 0.1 μg m(-3), for benzene, toluene, ethylbenzene, sum of m-, p-, o-xylenes, and naphthalene, respectively. Higher concentrations of VOCs were observed during the winter campaign, possibly due to slower dispersion, slower chemical transformations and/or the lengthy "cold start" period required by vehicles in the wintertime. A trajectory analysis showed that air masses coming from Eastern Europe carried significantly higher levels of PM(2.5) compared to masses from other regions, but the PAHs within the PM(2.5) are of local origin. It has been suggested that street dust, widely used for winter sanding activities in Eastern and Central European countries, may act not only as a source of PM, but also as source of particle-bound PAHs. Other potential sources include vehicle exhaust, domestic heating and long-range transport.     

Comparison of the SidePak personal monitor with the Aerosol Particle Sizer (APS)

The aim of this study was to compare the performance of the TSI Aerodynamic Particle Sizer (APS) and the TSI portable photometer SidePak to measure airborne oil mist particulate matter (PM) with aerodynamic diameters below 10 μm, 2.5 μm and 1 μm (PM(10), PM(2.5) and PM(1)). Three SidePaks each fitted with either a PM(10), PM(2.5) or a PM(1) impactor and an APS were run side by side in a controlled chamber. Oil mist from two different mineral oils and two different drilling fluid systems commonly used in offshore drilling technologies were generated using a nebulizer. Compared to the APS, the SidePaks overestimated the concentration of PM(10) and PM(2.5) by one order of magnitude and PM(1) concentrations by two orders of magnitude after exposure to oil mist for 3.3-6.5 min at concentrations ranging from 0.003 to 18.1 mg m(-3) for PM(10), 0.002 to 3.96 mg m(-3) for PM(2.5) and 0.001 to 0.418 mg m(-3) for PM(1) (as measured by the APS). In a second experiment a SidePak monitor previously exposed to oil mist overestimated PM(10) concentrations by 27% compared to measurements from another SidePak never exposed to oil mist. This could be a result of condensation of oil mist droplets in the optical system of the SidePak. The SidePak is a very useful instrument for personal monitoring in occupational hygiene due to its light weight and quiet pump. However, it may not be suitable for the measurement of particle concentrations from oil mist.     

Results of An Indoor Size Fractionated PM School Sampling Program in Libby, Montana

Libby, Montana is the only PM_2.5 nonattainment area in the western United States with the exceptions of parts of southern California. During January through March 2005, a particulate matter (PM) sampling program was conducted within Libby’s elementary and middle schools to establish baseline indoor PM concentrations before a wood stove change-out program is implemented over the next several years. As part of this program, indoor concentrations of PM mass, organic carbon (OC), and elemental carbon (EC) in five different size fractions (>2.5, 1.0–2.5, 0.5–1.0, 0.25–0.5, and <0.25 μm) were measured. Total measured PM mass concentrations were much higher inside the elementary school, with particle size fraction (>2.5, 0.5–1.0, 0.25–0.5, and <0.25 μm) concentrations between 2 and 5 times higher when compared to the middle school. The 1.0–2.5 μm fraction had the largest difference between the two sites, with elementary school concentrations nearly 10 times higher than the middle school values. The carbon component for the schools’ indoor PM was found to be predominantly composed of OC. Measured total OC and EC concentrations, as well as concentrations within individual size fractions, were an average of two to five times higher at the elementary school when compared to the middle school. For the ultrafine fraction (<0.25), EC concentrations were similar between each of the schools. Despite the differences in concentrations between the schools at the various fraction levels, the OC/EC ratio was determined to be similar.     

Indoor air quality during renovation actions: a case study

A temporary renovation activity releases considerably high concentrations of particulate matter, viable and non-viable, into air. These pollutants are a potential contributor to unacceptable indoor air quality (IAQ). Particulate matter and its constituents lead, sulfate, nitrate, chloride, ammonium and fungi as well as fungal spores in air were evaluated in a building during renovation action. Suspended dust was recorded at a mean value of 6.1 mg m(-3) which exceeded the Egyptian limit values for indoor air (0.15 mg m(-3)) and occupational environments (5 mg m(-3)). The highest particle frequency (23%) of aerodynamic diameter (dae) was 1.7 microm. Particulate sulfate (SO(4)(2-)), nitrate (NO(3)(-)), chloride (Cl(-)), ammonium (NH(4)(+)) and lead components of suspended dust averaged 2960, 28, 1350, 100 and 13.3 microg m(-3), respectively. Viable fungi associated with suspended dust and that in air averaged 1.11 x 10(6) colony forming unit per gram (cfu g(-1)) and 92 colony forming unit per plate per hour (cfu p(-1) h(-1)), respectively. Cladosporium(33%), Aspergillus(25.6%), Alternaria(11.2%) and Penicillium(6.6%) were the most frequent fungal genera in air, whereas Aspergillus(56.8%), Penicillium(10.3%) and Eurotium(10.3%) were the most common fungal genera associated with suspended dust. The detection of Aureobasidium, Epicoccum, Exophiala, Paecilomyces, Scopulariopsis, Ulocladium and Trichoderma is an indication of moisture-damaged building materials. Alternaria, Aureobasidium, Cladosporium, Scopulariopsis and Nigrospora have dae > 5 microm whereas Aspergillus, Penicillium and Verticillium have dae < 5 microm which are suited to penetrate deeply into lungs. Particulate matter from the working area infiltrates the occupied zones if precautionary measures are inadequate. This may cause deterioration of IAQ, discomfort and acute health problems. Renovation should be carefully designed and managed, in order to minimize degradation of the indoor and outdoor air quality.     

PM source apportionment and trace metallic aerosol affinities during atmospheric pollution episodes: a case study from Puertollano, Spain

Source apportionment study was performed, applying principal component analysis to the results of 221 chemical analyses of PM10 and PM2.5 samples collected daily from the industrial (but low traffic) Spanish town of Puertollano over a 14-month period during 2004-2005. Results reveal compositional variations attributable to different mixtures of natural and anthropogenic materials, mainly soil and rock dust (crustal), marine salt (only in PM10), petrochemical refinery emissions, and particles attributed to the combustion of local coal, which is unusually rich in Pb and Sb. During the study period there were 34 pollution episodes when PM10 exceeded 50 tg m(-3), mostly due to winter air temperature inversions, regional atmospheric stagnation, or African dust incursions (North African, NAF days: usually in summer). Whereas the crustal component during NAF episodes averaged 52% with a PM2.5/PM10 ratio of 0.54, this dropped to 29% and a PM2.5/PM10 of 0.67 during non-NAF days when anthropogenic materials predominated. Abnormally enhanced concentrations of pathfinder metallic trace elements provide additional evidence for source apportionment: thus aerosols with raised levels of Pb and Sb are associated with local coal combustion, Ni and V can be linked to petrochemical PM emissions, and Ti, Mn, Rb, and Ce are particularly characteristic of crustal dust incursions.     

Phthalate levels in Norwegian indoor air related to particle size fraction

Phthalates are found in numerous consumer products, including interior materials like polyvinyl chloride (PVC). Several studies have identified phthalates in indoor air. A recent case-control study demonstrated associations between allergic symptoms in children and the concentration of phthalates in dust collected from their homes. Here we have analyzed the content of selected phthalates in particulate matter (PM): PM(10) and PM(2.5) filter samples collected in 14 different indoor environments. The results showed the presence of the phthalates di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP), dicyclohexyl phthalate (DCHP) and diethyl hexyl phthalate (DEHP) in the samples. The dominating phthalate in both PM(10) and PM(2.5) samples from all locations was DBP. More than a 10-fold variation in the mean concentration of total phthalates between sampling sites was observed. The highest levels of total phthalates were detected in one children's room, one kindergarten, in two primary schools, and in a computer room. The relative contribution of total phthalates in PM(10) and PM(2.5) was 1.1 +/- 0.3% for both size fractions. The contribution of total phthalates in PM(2.5) to total phthalates in PM(10) ranged from 23-81%, suggesting different sources. Of the phthalates that were analyzed in the PM material, DBP was found to be the major phthalate in rubber from car tyres. However, our analyses indicate that tyre wear was of minor importance for indoor levels of both DBP as well as total phthalates. Overall, these results support the notion that inhalation of indoor PM contributes to the total phthalate exposure.     

A positive chemical ionization GC/MS method for the determination of airborne ethylene glycol and propylene glycols in non-occupational environments

An analytical method for ethylene glycol and propylene glycols has been developed for measuring airborne levels of these chemicals in non-occupational environments such as residences and office buildings. The analytes were collected on charcoal tubes, solvent extracted, and analyzed by gas chromatography-mass spectrometry using a positive chemical ionization technique. The method had a method detection limit of 0.07 microg m(-3) for ethylene glycol and 0.03 microg m(-3) for 1,2- and 1,3-propylene glycols, respectively, based on a 1.44 m3 sampling volume. Indoor air samples of several residential homes and other indoor environments have been analyzed. The median concentrations of ethylene glycol and 1,2-propylene glycol in nine residential indoor air samples were 53 microg m(-3) and 13 microg m(-3) respectively with maximum values of 223 microg m(-3) and 25 microg m(-3) detected for ethylene glycol and 1,2-propylene glycol respectively. The concentrations of these two chemicals in one office and two laboratories were at low microg m(-3) levels. The maximum concentration of 1,3-propylene glycol detected in indoor air was 0.1 microg m(-3).     

桂林市细颗粒物部分典型排放源的粒径谱及成分分析

采用在线单颗粒气溶胶质谱技术源解析方法,对桂林市PM2.5典型排放源的粒径和化学成分进行质谱分析,采集燃煤/燃气源、工业工艺源、扬尘源、油烟源4类共计7个典型排放源。结果表明,桂林市4类排放源细颗粒物的粒径分布为0.25~1.25μm,80%以上的细颗粒分布在0.2~1.0μm的小粒径范围,峰值约0.68μm。细颗粒物离子成分含有Na~+、Mg~+、K~+、NH~+4、Fe~+、Pb~+、Cd~+、V~+、Mn~+、Li~+、Al~+、Ca~+、Cu~+、Zn~+、Cr~+、CN~-、PO_3~-、NO_2~-、NO_3~-、Cl~-、SO_4~(2-)、SiO_3~-等成分,桂林市细颗粒物为元素碳、有机碳元素碳、有机碳、富锰颗粒、富铁颗粒、富钾颗粒、矿物质、左旋葡聚糖以及其他金属等9类。     

Health risk assessment of occupational exposure to particulate-phase polycyclic aromatic hydrocarbons associated with Chinese, Malay and Indian cooking

Food cooking using liquefied petroleum gas (LPG) has received considerable attention in recent years since it is an important source of particulate air pollution in indoor environments for non-smokers. Exposure to organic compounds such as polycyclic aromatic hydrocarbons (PAHs) contained in particles is of particular health concern since some of these compounds are suspected carcinogens. It is therefore necessary to chemically characterize the airborne particles emitted from gas cooking to assess their possible health impacts. In this work, the levels of fine particulate matter (PM(2.5)) and 16 priority PAHs were determined in three different ethnic commercial kitchens, specifically Chinese, Malay and Indian food stalls, where distinctive cooking methods were employed. The mass concentrations of PM(2.5) and PAHs, and the fraction of PAHs in PM(2.5) were the highest at the Malay stall (245.3 microg m(-3), 609.0 ng m(-3), and 0.25%, respectively), followed by the Chinese stall (201.6 microg m(-3), 141.0 ng m(-3), and 0.07%), and the Indian stall (186.9 microg m(-3), 37.9 ng m(-3), and 0.02%). This difference in the levels of particulate pollution among the three stalls may be attributed to the different cooking methods employed at the food stalls, the amount of food cooked, and the cooking time, although the most sensitive parameter appears to be the predominant cooking method used. Frying processes, especially deep-frying, produce more air pollutants, possibly due to the high oil temperatures used in such operations. Furthermore, it is found that frying, be it deep-frying at the Malay stall or stir-frying at the Chinese stall, gave rise to an abundance of higher molecular weight PAHs such as benzo[b]fluoranthene, indeno[1,2,3-cd]pyrene and benzo[g,h,i]perylene whereas low-temperature cooking, such as simmering at the Indian stall, has a higher concentration of lower molecular weight PAHs. In addition, the correlation matrices and diagnostic ratios of PAHs were calculated to determine the markers of gas cooking. To evaluate the potential health threat due to inhalation exposure from the indoor particulate pollution, excess lifetime cancer risk (ELCR) was also calculated for an exposed individual. The findings suggest that cooking fumes in the three commercial kitchens pose adverse health effects.     

Submicrometer elemental carbon as a selective measure of diesel particulate matter in coal mines

A monitoring method for diesel particulate matter was published as Method 5040 by the National Institute for Occupational Safety and Health (NIOSH). Organic and elemental carbon are determined by the method, but elemental carbon (EC) is a better exposure measure. The US Mine Safety and Health Administration (MSHA) proposed use of NIOSH 5040 for compliance determinations in metal and nonmetal mines. MSHA also published a rulemaking for coal mines, but no exposure standard was provided. A standard based on particulate carbon is not considered practical because of coal dust interference. Interference may not be a problem if an appropriate size-selective sampler and EC exposure standard are employed. Submicrometer dust concentrations found in previous surveys of nondieselized, underground coal mines were relatively low. If a large fraction of the submicrometer dust is organic and mineral matter, submicrometer EC concentrations would be much lower than submicrometer mass concentrations. Laboratory and field results reported herein indicate the amount of EC contributed by submicrometer coal dust is minor. In a laboratory test, a submicrometer EC concentration of 31 microg m(-3) was found when sampling a respirable coal dust concentration over three times the US compliance limit (2 mg m(-3)). Laboratory results are consistent with surveys of nondieselized coal mines, where EC results ranged from below the method limit of detection to 18 microg m(-3) when size-selective samplers were used to collect dust fractions having particle diameters below 1.5 microm-submicrometer EC concentrations were approximate 7 microg m(-3). In dieselized mines, submicrometer EC concentrations are much higher.     

Ambient site, home outdoor and home indoor particulate concentrations as proxies of personal exposures

Despite strong longitudinal associations between particle personal exposures and ambient concentrations, previous studies have found considerable inter-personal variability in these associations. Factors contributing to this inter-personal variability are important to identify in order to improve our ability to assess particulate exposures for individuals. This paper examines whether ambient, home outdoor and home indoor particle concentrations can be used as proxies of corresponding personal exposures. We explore the strength of the associations between personal, home indoor, home outdoor and central outdoor monitoring site ("ambient site") concentrations of sulfate, fine particle mass (PM(2.5)) and elemental carbon (EC) by season and subject for 25 individuals living in the Boston, MA, USA area. Ambient sulfate concentrations accounted for approximately 70 to 80% of the variability in personal and indoor sulfate levels. Correlations between ambient and personal sulfate, however, varied by subject (0.1-1.0), with associations between personal and outdoor sulfate concentrations generally mirroring personal-ambient associations (median subject-specific correlations of 0.8 to 0.9). Ambient sulfate concentrations are good indicators of personal exposures for individuals living in the Boston area, even though their levels may differ from actual personal exposures. The strong associations for sulfate indicate that ambient concentrations and housing characteristics are the driving factors determining personal sulfate exposures. Ambient PM(2.5) and EC concentrations were more weakly associated with corresponding personal and indoor levels, as compared to sulfate. For EC and PM(2.5), local traffic, indoor sources and/or personal activities can significantly weaken associations with ambient concentrations. Infiltration was shown to impact the ability of ambient concentrations to reflect exposures with higher exposures to particles from ambient sources during summer. In contrast in the winter, lower infiltration can result in a greater contribution of indoor sources to PM(2.5) and EC exposures. Placing EC monitors closer to participants' homes may reduce exposure error in epidemiological studies of traffic-related particles, but this reduction in exposure error may be greater in winter than summer. It should be noted that approximately 20% of the EC data were below the field limit of detection, making it difficult to determine if the weaker associations with the central site for EC were merely a result of methodological limitations.     

Concentration gradient patterns of aerosol particles near interstate highways in the Greater Cincinnati airshed

The objective of this study was to determine if there is an exposure gradient in particulate matter concentrations for people living near interstate highways, and to determine how far from the highway the gradient extends. Air samples were collected in a residential area of Greater Cincinnati in the vicinity of two major highways. The measurements were conducted at different distances from the highways by using ultrafine particle counters (measurement range: 0.02-1 microm), optical particle counters (0.3-20 microm), and PM2.5 Harvard Impactors (0.02-2.5 microm). The collected PM2.5 samples were analyzed for mass concentration, for elemental and organic carbon, and for elemental concentrations. The results show that the aerosol concentration gradient was most clearly seen in the particle number concentration measured by the ultrafine particle counters. The concentration of ultrafine particles decreased to half between the sampling points located at 50 m and 150 m downwind from the highway. Additionally, elemental analysis revealed a gradient in sulfur concentrations up to 400 m from the highway in a residential area that does not have major nearby industrial sources. This gradient was qualitatively attributed to the sulfate particle emissions from diesel engine exhausts, and was supported by the concentration data on several key elements indicative of traffic sources (road dust and diesel exhaust). As different particulate components gave different profiles of the diesel exposure gradient, these results indicate that no single element or component of diesel exhaust can be used as a surrogate for diesel exposure, but more comprehensive signature analysis is needed. This characterization is crucial especially when the exposure data are to be used in epidemiological studies.