The application of dustiness tests to the prediction of worker dust exposure

Laboratory bench tests, known as dustiness tests, have been used to evaluate and compare the potential of various powders to cause occupational dust exposure. Dustiness tests are used to develop products with reduced dust emissions. The correlation between dustiness test results and dust exposures was evaluated at two bag dumping and bag filling operations. At one bag dumping and one bag filling operation, there was evidence of a relationship between dustiness test results and dust exposures. In one case, regression analysis showed that dust exposures could be predicted to within nearly one order of magnitude. The variability in this prediction was caused by the inherent variability in the occupational dust exposures. In the other case, there was evidence of a correlation after the data had been adjusted for the effect of varying drop height. At the remaining two operations, no correlation between dust exposures and dustiness test results were observed. These results indicate that the relevance of dustiness tests to occupational dust exposure needs to be evaluated at each site. Because a better option does not exist, manufacturers should continue to use empirical dustiness tests to develop better products in the laboratory. The conclusions reached in the laboratory need to be validated by dust exposure measurements in the field, however.     

Exposure Assessment of Four Pharmaceutical Powders Based on Dustiness and Evaluation of Damaged HEPA Filters

In this study, we show the different dustiness characteristics of four molecular pharmaceutical powder candidates and evaluate the performance of HEPA filters damaged with three different pinhole sizes and exposed to dust using real industrial powders in a miniaturized EN15051 rotating drum dustiness tester. We then demonstrate the potential use of such data using first-order exposure modeling to assess the potential worker exposure and transmission of active powder ingredients into ventilation systems. The four powders had highly variable inhalable dustiness indices (1,036 – 14,501 mg/kg). Dust particle size-distributions were characterized by three peaks; the first occurred around 60–80 nm, the second around 250 nm, and the third at 2–3 μm. The second and third peaks are often observed in dustiness test studies, but peaks in the 60–80 nm range have not been previously reported. Exposure modeling in a 5 times 20 kg powder pouring scenario, suggests that excessive dust concentrations may be reached during use of powders with the highest dustiness levels. By number, filter-damage by three pinhole sizes resulted in damage-dependent penetration of 70–80 nm-size particles, but by volume and mass the penetration is still dominated by particles larger than 100 nm. Whereas the exposure potential was evident, the potential dust concentrations in air ducts following the pouring scenario above were at pg/m³ levels. Hence, filter penetration at these damage levels was assumed to be only critical, if the active ingredients were associated with high hazard or unique product purity is required.

[Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: An example of a typical particle number time-series of a complete dustiness test. It provides information on the HEPA-filter used including a scanning electron microscopy image of it. It also provides APS-measurements of particles penetrating the damaged HEPA-filter.]     

Size selective dustiness and exposure; simulated workplace comparisons

A simulated workplace study was conducted to investigate the relation between inhalation exposure and dustiness determined with a rotating drum dustiness tester. Three powders were used in the study, i.e. magnesium stearate, representing a very dusty powder, and aluminium oxide and calcium carbonate, representing low and very low dusty powders, respectively. Two scenarios of handling small volume of powders were included; sweeping/cleaning and scooping/weighing/adding. Size-selective dust exposure was assessed using MultiDust (dual-fraction) IOM and RespiCon sampling heads. For the present operation scenarios, dustiness showed itself to be the major determinant of exposure and explained approximately 70% of the exposure variances. The ratios of respirable and inhalable fractions as determined by dustiness tests were comparable with the ratios observed for exposure. The results emphasize the relevance of dustiness as a parameter to characterize substances according to potential for exposure.     

不同通风方式对消化内镜清洗消毒室气溶胶净化效果的研究

 目的 评价轴流风柜机械通风、排风扇机械通风和自然通风3种方式净化消化内镜清洗消毒室气溶胶的效果。方法 试验分为轴流风柜机械通风(A组)、排风扇机械通风(B组)、自然通风(C组)3组。采集某院两个病区3组通风方式下消化内镜清洗消毒室静态环境(清洗消毒工作停止12 h)通风2 h前后,动态环境(清洗消毒工作进行中)工作起始状态0 h以及持续通风1、2、4、6 h的空气,检测空气气溶胶中颗粒物、微生物、戊二醛的含量,比较3种通风方式净化消化内镜清洗消毒室气溶胶的效果。结果 消化内镜清洗消毒室在静态环境下,3组通风方式通风2 h后,空气中颗粒物、微生物和戊二醛含量均呈下降趋势,其中A、B组通风2 h前后比较,差异具有统计学意义(P＜0.05)。清洗消毒室在工作起始状态0 h时,3组空气中颗粒物、微生物和戊二醛含量比较,差异均无统计学意义(均P>0.05)。持续通风1、2、4、6 h时,总体及任意两组间空气中颗粒物、微生物和戊二醛含量比较,差异均有统计学意义(均P＜0.01),且A组低于B、C组,B组低于C组。A组在动态环境下空气中颗粒物、微生物和戊二醛含量较低且波动范围小,其中颗粒物含量在100万级洁净室规定范围内。B、C组在持续通风1、2、4 h时戊二醛含量均超出最大安全接触限值0.175 mg/m³,其中C组在4~6 h (午休期间)的戊二醛含量仍超出最大安全限值。结论 3种通风方式中,轴流风柜机械通风方式能有效净化消化内镜清洗消毒室的气溶胶,建议引入轴流风柜通风方式,以保障工作人员的职业安全。     

Impact Assessment of Respirable Suspended Particulate Matter from Diesel Generator Sets Used for Pumping Station

Prediction of respirable suspended particulate matter impacts of diesel generator sets used for pumping station has been made using meteorological data, information on stack characteristics and emission rate, baseline ambient particulate matter and Industrial Source Complex Short Term (ISCST-3) model. It is observed that particulate matter emission from pumping station-S workplace diesel generator sets ranged from 2.4 to 436.5 mg Nm⁻³ and while at pumping station-C, it ranged from 23.2 to 186.5 mgNm⁻³. The predicted and ambient respirable suspended particulate matter concentrations are below the national air quality standard for respirable suspended particulate matter in a mixed industrial area. Metals contents in respirable suspended particulate matter indicate the origin of crustal and mobile sources. Therefore, the impact of diesel generator sets used for pumping of crude oil on local air quality would be acceptable.     

The Po River Delta (north Italy) indoor epidemiological study: effects of pollutant exposure on acute respiratory symptoms and respiratory function in adults

The authors studied the effects of relatively low doses of nitrogen dioxide and respirable suspended particulate matter (i.e., < 2.5 mu) on acute respiratory symptoms and on peak expiratory flow in 383 adults (15-72 yr of age) who lived in the Po River Delta area, located near Venice. During 2 wk-1 wk in winter and 1 wk in summer--the authors monitored each participant's house to measure nitrogen dioxide (in parts per billion) and respirable suspended particulate (microgram/m3) concentration. Information on sex, age, height, weight, daily activity patterns, active and passive smoking, chronic respiratory diseases, daily peak expiratory flow, and presence of acute respiratory symptoms during the weeks monitoring occurred were also collected. Peak expiratory flow variation was studied as mean amplitude percentage (i.e., amplitude/mean) and percentage of diurnal variation (maximum/minimum). The exposure indices to nitrogen dioxide (nitrogen dioxide--index of exposure) and to respirable suspended particulate matter (respirable suspended particulate matter-index of exposure) were computed as the product of pollutant concentration and time of exposure. The authors considered indices as "low" or "high" on the basis of the median value. The median nitrogen dioxide was 20 ppb in winter and 14 ppb in summer; the highest nitrogen dioxide levels occurred in the kitchen in the winter (33 ppb) and summer (20 ppb). The median respirable suspended particulate matter was 68 micrograms/m3 in winter and 45 micrograms/m3 in summer. Only in winter were there significant associations between bronchitic/asthmatic symptoms and "high" nitrogen dioxide and respirable suspended particulate matter indices. In subjects who did not smoke, a significant influence of the "high" respirable suspended particulate matter-index of exposure was also observed in summer. With respect to peak expiratory flow and its variability, respirable suspended particulate matter-index of exposure was associated with an increase of both amplitude/mean and maximum/mean; however, with respect to the nitrogen dioxide--index of exposure, the association was significant only in subjects with chronic respiratory diseases (i.e., asthma and bronchitis). These relationships were significant only in winter. In conclusion, the results of the current study indicate that there is an association between relatively low doses of pollutants and acute respiratory symptoms and peak expiratory flow in adults.     

The Po River Delta (North Italy) Indoor Epidemiological Study: Effects of Pollutant Exposure on Acute Respiratory Symptoms and Respiratory Function in Adults

The authors studied the effects of relatively low doses of nitrogen dioxide and respirable suspended particulate matter (i.e., < 2.5 μ) on acute respiratory symptoms and on peak expiratory flow in 383 adults (15–72 yr of age) who lived in the Po River Delta area, located near Venice. During 2 wk—1 wk in winter and 1 wk in summer—the authors monitored each participant's house to measure nitrogen dioxide (in parts per billion) and respirable suspended particulate (μg/m³) concentration. Information on sex, age, height, weight, daily activity patterns, active and passive smoking, chronic respiratory diseases, daily peak expiratory flow, and presence of acute respiratory symptoms during the weeks monitoring occurred were also collected. Peak expiratory flow variation was studied as mean amplitude percentage (i.e., amplitude/mean) and percentage of diurnal variation (maximum/minimum). The exposure indices to nitrogen dioxide (nitrogen dioxide-index of exposure) and to respirable suspended particulate matter (respirable suspended particulate matter-index of exposure) were computed as the product of pollutant concentration and time of exposure. The authors considered indices as “low” or “high” on the basis of the median value. The median nitrogen dioxide was 20 ppb in winter and 14 ppb in summer; the highest nitrogen dioxide levels occurred in the kitchen in the winter (33 ppb) and summer (20 ppb). The median respirable suspended particulate matter was 68 μg/m³ in winter and 45 μg/m³ in summer. Only in winter were there significant associations between bronchitic/asthmatic symptoms and “high” nitrogen dioxide and respirable suspended particulate matter indices. In subjects who did not smoke, a significant influence of the “high” respirable suspended particulate matter-index of exposure was also observed in summer. With respect to peak expiratory flow and its variability, respirable suspended particulate matter-index of exposure was associated with an increase of both amplitude/mean and maximum/mean; however, with respect to the nitrogen dioxide-index of exposure, the association was significant only in subjects with chronic respiratory diseases (i.e., asthma and bronchitis). These relationships were significant only in winter. In conclusion, the results of the current study indicate that there is an association between relatively low doses of pollutants and acute respiratory symptoms and peak expiratory flow in adults.     

Test-plot studies on runoff of sulfonamides from manured soils after sprinkler irrigation

Three test-plot series have been performed to gather information on runoff of sulfonamides from manured arable and grassland after sprinkler irrigation. To prepare test slurries with defined aged residues, liquid bovine manure was fortified with sulfadiazine, sulfadimidine, and sulfamethoxazole and stored short-term. After test-slurry application, the arable land was treated by soil cultivation before irrigation, and the manured grassland was irrigated directly with 50 mm h(-1) for 2 h. The runoff suspensions were sampled at 5- to 10-min intervals, separated into aqueous phase and suspended matter and residue analyzed. Higher runoff emissions were found from manured grassland plots. The discharge volumes ranged from 106 to 252 L and the total runoff emissions ranged from 13 to 28% of sulfonamides applied initially. Within the first 20 min of the irrigation period that represented a rainfall of 17 mm, emissions, on average, were 4%. The loads of sulfonamides predominantly occurred in the runoff water. The only emissions via suspended matter, on average, were 0.02%. On arable land, however, the runoff was reduced by soil cultivation. Discharge volumes and sulfonamide emissions were 36 to 128 L and 0.1 to 2.5%, respectively. Despite the high-intensity sprinkler irrigation, major emissions did not occur until a 60-min delay.     

Modeled Occupational Exposures to Gas-Phase Medical Laser-Generated Air Contaminants

Exposure monitoring data indicate the potential for substantive exposure to laser-generated air contaminants (LGAC); however the diversity of medical lasers and their applications limit generalization from direct workplace monitoring. Emission rates of seven previously reported gas-phase constituents of medical laser-generated air contaminants (LGAC) were determined experimentally and used in a semi-empirical two-zone model to estimate a range of plausible occupational exposures to health care staff. Single-source emission rates were generated in an emission chamber as a one-compartment mass balance model at steady-state. Clinical facility parameters such as room size and ventilation rate were based on standard ventilation and environmental conditions required for a laser surgical facility in compliance with regulatory agencies. All input variables in the model including point source emission rates were varied over an appropriate distribution in a Monte Carlo simulation to generate a range of time-weighted average (TWA) concentrations in the near and far field zones of the room in a conservative approach inclusive of all contributing factors to inform future predictive models. The concentrations were assessed for risk and the highest values were shown to be at least three orders of magnitude lower than the relevant occupational exposure limits (OELs). Estimated values do not appear to present a significant exposure hazard within the conditions of our emission rate estimates.     

Health effects of a mixture of indoor air volatile organics, their ozone oxidation products, and stress

In our present study we tested the health effects among women of controlled exposures to volatile organic compounds (VOCs), with and without ozone (O3), and psychological stress. Each subject was exposed to the following three conditions at 1-week intervals (within-subject factor): VOCs (26 mg/m3), VOCs + O3 (26 mg/m3 + 40 ppb), and ambient air with a 1-min spike of VOCs (2.5 mg/m3). As a between-subjects factor, half the subjects were randomly assigned to perform a stressor. Subjects were 130 healthy women (mean age, 27.2 years; mean education, 15.2 years). Health effects measured before, during, and after each 140-min exposure included symptoms, neurobehavioral performance, salivary cortisol, and lung function. Mixing VOCs with O3 was shown to produce irritating compounds including aldehydes, hydrogen peroxide, organic acids, secondary organic aerosols, and ultrafine particles (particulate matter with aerodynamic diameter < 0.1 microm). Exposure to VOCs with and without O3 did not result in significant subjective or objective health effects. Psychological stress significantly increased salivary cortisol and symptoms of anxiety regardless of exposure condition. Neither lung function nor neurobehavioral performance was compromised by exposure to VOCs or VOCs + O3. Although numerous epidemiologic studies suggest that symptoms are significantly increased among workers in buildings with poor ventilation and mixtures of VOCs, our acute exposure study was not consistent with these epidemiologic findings. Stress appears to be a more significant factor than chemical exposures in affecting some of the health end points measured in our present study.     

空气细颗粒物对交通警察肺通气功能及呼吸道症状的影响

目的 研究空气细颗粒物(PM2.5)暴露对交通警察呼吸道症状及肺通气功能的影响.方法 使用个体采样器测定上海市区107名男性外勤交通警察(高暴露组)及101名居民(一般暴露组)PM2.5的暴露情况,问卷调查获得交通警察和居民的基本情况、呼吸道症状,测定用力呼气肺活量(FVC)、第1秒用力呼气容积(FEV1.0)、FEV1.0/FVC%和最大呼出流速(PEF).比较交通警察和居民PM2.5暴露及呼吸道症状、肺通气功能的差异,对交通警察按工龄分组,研究工龄对肺通气功能的影响,并对肺通气功能降低与颗粒物暴露水平的进行相关分析.结果 交通警察和居民细颗粒物24 h个体平均暴露浓度为分别(115.4±46.17)和(74.94±40.09)μg/m3,高暴露组PM2.5暴露水平明显高于一般暴露组,差异有统计学意义(P＜0.01).高暴露组咳嗽、咳痰、咽部不适及气喘、气短和鼻部不适的发生率明显高于一般暴露组,差异有统计学意义(P＜0.05,P＜0.01),高暴露组肺通气功能指标FVC实测/FVC预计%和FEV 1.0实测/FEV1.0预计%的异常率分别为25.23%和12.15%,一般暴露组FVC实测/FVC预计%和FEV1.0实测/FEV1.0预计%的异常率分别为11.88%和2.97%,两组比较,差异有统计学意义(P＜0.05,P＜0.01),且高暴露组FVC实测/FVC预计%、FEV1.0实测/FEV1.0预计%异常率随工龄延长呈现升高的趋势.结论 长期暴露于较高水平的PM2.5会危害人体呼吸系统健康,导致呼吸道症状增多,降低肺通气功能.     

Base camp personnel exposure to particulate matter during wildland fire suppression activities

Wildland fire base camps commonly house thousands of support personnel for weeks at a time. The selection of the location of these base camps is largely a strategic decision that incorporates many factors, one of which is the potential impact of biomass smoke from the nearby fire event. Biomass smoke has many documented adverse health effects due, primarily, to high levels of fine particulate matter (PM(2.5)). Minimizing particulate matter exposure to potentially susceptible individuals working as support personnel in the base camp is vital. In addition to smoke from nearby wildland fires, base camp operations have the potential to generate particulate matter via vehicle emissions, dust, and generator use. We monitored particulate matter at three base camps during the fire season of 2009 in Washington, Oregon, and California. During the sampling events, 1-min time-weighted averages of PM(2.5) and particle counts from three size fractions (0.3-0.5 microns, 0.5-1.0 microns, and 1.0-2.5 microns) were measured. Results showed that all PM size fractions (as well as overall PM(2.5) concentrations) were higher during the overnight hours, a trend that was consistent at all camps. Our results provide evidence of camp-based, site-specific sources of PM(2.5) that could potentially exceed the contributions from the nearby wildfire. These exposures could adversely impact wildland firefighters who sleep in the camp, as well as the camp support personnel, who could include susceptible individuals. A better understanding of the sources and patterns of poor air quality within base camps would help to inform prevention strategies to reduce personnel exposures.     

An investigation of dust generation by free falling powders.

To identify the dust generation processes, aluminum oxide powder was dropped as a free falling slug in a test chamber. The effect of the slug's mass, diameter, and drop height upon the aerosol concentration and size distribution was measured with an aerodynamic particle sizer. To differentiate between aerosol generated during the free fall and at the end of the fall, the slug was dropped either onto a flat surface or into a container of water that suppressed dust generation associated with the impact at the end of the fall. Aerosol generation occurred during the slug's free fall as well as at the end of the fall. The falling solid induced an airflow that followed the falling solid to the end of the fall. This induced airflow contained the aerosol generated during the free fall. At the end of the free fall, the induced airflow, combined with air jets created on impact, dispersed the aerosol throughout the test chamber. Additional measurements were made by using "neutral buoyancy" helium-filled bubbles to visualize the airflow in the test chamber. The airflow and ensuing turbulence were sufficient to keep large, inspirable particles suspended throughout the test chamber for periods greater than 10 min. During experimental work, the effect of drop height, mass, and slug diameter upon aerosol generation by a single slug of powder was studied. The results indicated that the manner in which a powder is handled may be as important as material dustiness as measured by a dustiness tester. Aerosol generation can be reduced by minimizing the contact between the falling powder and the air.     

Indoor air quality in a middle school, Part II: Development of emission factors for particulate matter and bioaerosols

A middle school (grades 6 to 8) in a residential section of Springfield, Illinois, with no known air quality problems, was selected for a baseline indoor air quality survey. The study was designed to measure and evaluate air quality at the middle school with the objective of providing a benchmark for comparisons with measurements in schools with potential air quality problems. The focus of this article is on the development of emission factors for particulate matter and bioaerosols. The school was characterized as having no health complaints and good maintenance schedules. Four indoor locations including the cafeteria, a science classroom, an art classroom, the lobby outside the main office, and one outdoor location were sampled for various environmental comfort and pollutant parameters for one week in February 1997. Integrated samples (eight-hour sampling time) for respirable and total particulate matter, and short-term measurements (two-minute samples, three times per day) for bioaerosols were collected on three consecutive days at each of the sampling sites. Continuous measurements of carbon dioxide were logged at all locations for five days. Continuous measurements of respirable particulate matter were also collected in the lobby area. A linear relationship between occupancy and corresponding carbon dioxide and particle concentrations was seen. A completely mixed space, one compartment mass balance model with estimated CO2 generation rates and actual CO2 and particulate matter concentrations was used to model ventilation and pollutant emission rates. Emission factors for occupancy were represented by the slope of emission rate versus occupancy scatter plots. The following particle and bioaerosol emission factors were derived from the indoor measurements: total particles: 1.28 mg/hr/person-hr; respirable particles: 0.154 g/hr/person-hr; total fungi: 167 CFU/hr/person-min; thermophilic fungi: 35.8 CFU/hr/person-min; mesophilic fungi: 119 CFU/hr/person-min; total bacteria: 227 CFU/hr/person-min; gram-negative bacteria: 69.5 CFU/hr/person-min; gram-positive bacteria: 191 CFU/hr/person-min; Aspergillus: 17.0 CFU/hr/person-min; Penicillium: 161 CFU/hr/person-min; and yeasts: 16.4 CFU/hr/person-min.     

Particle size distribution: A key factor in estimating powder dustiness

A wide variety of raw materials, involving more than 20 samples of quartzes, feldspars, nephelines, carbonates, dolomites, sands, zircons, and alumina, were selected and characterised. Dustiness, i.e., a materials' tendency to generate dust on handling, was determined using the continuous drop method. These raw materials were selected to encompass a wide range of particle sizes (1.6–294 µm) and true densities (2650–4680 kg/m³).

The dustiness of the raw materials, i.e., their tendency to generate dust on handling, was determined using the continuous drop method. The influence of some key material parameters (particle size distribution, flowability, and specific surface area) on dustiness was assessed. In this regard, dustiness was found to be significantly affected by particle size distribution.

Data analysis enabled development of a model for predicting the dustiness of the studied materials, assuming that dustiness depended on the particle fraction susceptible to emission and on the bulk material's susceptibility to release these particles. On the one hand, the developed model allows the dustiness mechanisms to be better understood. In this regard, it may be noted that relative emission increased with mean particle size. However, this did not necessarily imply that dustiness did, because dustiness also depended on the fraction of particles susceptible to be emitted. On the other hand, the developed model enables dustiness to be estimated using just the particle size distribution data. The quality of the fits was quite good and the fact that only particle size distribution data are needed facilitates industrial application, since these data are usually known by raw materials managers, thus making additional tests unnecessary.

This model may therefore be deemed a key tool in drawing up efficient preventive and/or corrective measures to reduce dust emissions during bulk powder processing, both inside and outside industrial facilities. It is recommended, however, to use the developed model only if particle size, true density, moisture content, and shape lie within the studied ranges.     

A novel device for measuring respirable dustiness using low-mass powder samples

Respirable dustiness represents the tendency of a powder to generate respirable airborne dust during handling and therefore indicates the propensity for a powder to become an inhalation hazard. The dustiness of 14 powders, including 10 different nanopowders, was evaluated with the use of a novel low-mass dustiness tester designed to minimize the use of the test powder. The aerosol created from 15-mg powder samples falling down a tube were measured with an aerodynamic particle sizer (APS). Particle counts integrated throughout the pulse of aerosol created by the falling powder were used to calculate a respirable dustiness mass fraction (D, mg/kg). An amorphous silicon dioxide nanopowder produced a respirable D of 121.4 mg/kg, which was significantly higher than all other powders (p < 0.001). Many nanopowders produced D values that were not significantly different from large-particle powders, such as Arizona Road Dust and bentonite clay. In general, fibrous nanopowders and powders with primary particles >100 nm are not as dusty as those containing granular, nano-sized primary particles. The method used here, incorporating an APS, represents a deviation from a standard method but resulted in dustiness values comparable to other standard methods.     

Particulate matter (PM) exposure assessment--horizontal and vertical PM profiles in relation to agricultural activities and environmental factors in farm fields

Reports profiling airborne particulate matter (PM) in farm fields, especially during a Class B biosolids land-injection process, are scarce. Thus, this study characterized PM in such a farm field located in northwest Ohio. For comparison, a control farm field with no biosolids application history was also monitored. During 11?days of varied agricultural activities, the concentrations of particle mass and number (count) and also metal content were monitored in the study field, and their interactions with environmental factors were examined. The monitoring was performed across the farm field at four heights of 0.5, 1.5, 2.5, and 3.5?m from the ground. The overall mean (SD) concentration (μg/m(3)) of respirable suspended particulate matter (RPM) was 30.8 (23.1) with means ranging from 15.9 (3.80) during post-tilling Event 1, 19.9 (12.4) during biosolids application to 56.1 (11.7) during post-harvest (including baling) activity. The maximum concentration of RPM (μg/m(3)) was 43 during biosolids application, 90 during post-harvest, and 183 during post-tilling Event 2 activities. Overall, 93.7% (8.98%) of the total suspended particulate matter (TPM) was respirable. The levels of RPM significantly (p < 0.01) correlated with TPM and particle counts of ultrafine particles (UFP) and 0.3?μm particle size. Ambient temperature showed no effect, whereas wind speed and relative humidity had an inverse effect on RPM concentration. Particle concentrations changed minimally during each set of monitoring across the field, except during major activities or sudden weather changes. For particles with sizes of 2, 5, and 10?μm, the counts decreased with increasing height from the ground and were significantly (p < 0.05) higher at 0.5?m than at other heights. The levels of nine metals within particles monitored were well below current recommended occupational exposure criteria. These results suggest that injection of the biosolids into agricultural land provides significant protection against exposure to biosolids particles.     

An international survey of indoor air quality,ventilation, and smoking activity in restaurants: a pilot study

During a pilot study of indoor air quality in restaurants, a survey was performed in 34 medium-priced restaurants in six countries in Asia, Europe, and North America using a uniform protocol. The concentration of selected constituents of environmental tobacco smoke (ETS) present in occupied areas was determined during lunch and dinner periods by measuring the levels of four particulate-phase markers and two gas-phase markers. The particulate-phase markers determined were respirable suspended particles, ultraviolet particulate matter, fluorescing particulate matter, and solanesol particulate matter. The gas-phase markers were nicotine and 3-ethenylpyridine (3-EP). Correlation between the markers was investigated to explore an improved monitoring approach. It was concluded that at least one marker in each phase was necessary to describe adequately the ETS load. An assessment was made of the ventilation system in each restaurant, and effective ventilation rates were determined based on CO(2) measurements. Smoking activity was also monitored. These data were used to model nicotine and 3-EP concentrations that resulted in a satisfactory prediction of their levels, especially at the higher concentrations. A total number of 1370 questionnaires were returned by the restaurant patrons in five countries. In some countries, dissatisfaction rates above 20% were observed for draft, freshness of air, and noise. The dissatisfaction rates related to tobacco smoke were less than 20%, which is lower than would be predicted based on measured ETS levels. Based on the results of this international pilot study, recommendations are given for future studies of this type.     

Increase of urinary concentrations of 8-hydroxy-2′-deoxyguanosine in diesel exhaust emission inspector exposed to polycyclic aromatic hydrocarbons

Purpose  

The objectives of this study were to explore the factors influencing urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels in diesel engine exhaust emission inspectors (inspectors), the association between polycyclic aromatic hydrocarbons (PAHs) exposure and fine particulate matter (PM_2.5) levels in diesel exhaust particles (DEPs), and the PAHs exposure levels in diesel vehicle emission inspection stations (inspection stations).     

Time variant exposure analysis (TVEA): a measurement tool for characterizing particulate exposure determinants in construction

A work sampling-based approach, time variant exposure analysis (TVEA), was developed for assessment of determinants for particulate air contaminants in dynamic construction environments. To use TVEA, the field researcher records observations at fixed intervals to systematically survey over 30 potential determinants that could affect exposure to three types of particulate matter: quartz-containing dusts, diesel exhaust, and a general grouping of "other particles" that includes welding fume and wood dust. Two field studies were conducted to address questions of inter-rater reliability (n = 20) and coding interval appropriateness (n = 21) for the TVEA method. At least substantial inter-rater agreement (kappa > 0.60) was obtained for the TVEA variables related to tool or machine use, process, material, source intensity, and source orientation. Kappa values for source direction (0.22-0.38) and number of sources (0.38-0.60) showed comparatively lower agreement for all particulate types. Observation interval appropriateness was analyzed using linear regression to compare a 5-min observation interval "gold standard" with alternate intervals. Regression statistics indicated that while 30 min is an acceptable interval for exposure assessment, 15 min optimizes precision and practicality by ensuring that 95% of all observations differ less than ten percentage points from the "true" values. TVEA is a useful exposure assessment tool for the dynamic construction environment. It is flexible in that only those determinants that are of interest need be coded and the coding interval can be adjusted to accommodate the level of precision desired.