Maryanne G. Boundy

Indoor air pollutants and health in the United Arab Emirates

Background: Comprehensive global data on the health effects of indoor air pollutants are lacking. There are few large population-based multi–air pollutant health assessments. Further, little is known about indoor air health risks in the Middle East, especially in countries undergoing rapid economic development. Objectives: To provide multifactorial indoor air exposure and health data, we conducted a population-based study of indoor air pollution and health in the United Arab Emirates (UAE). Methods: We conducted a cross-sectional study in a population-based sample of 628 households in the UAE. Indoor air pollutants [sulfur dioxide (SO2), nitrogen dioxide (NO2), hydrogen sulfide (H2S), formaldehyde (HCHO), carbon monoxide (CO), and particulate matter] were measured using passive samplers over a 7-day period. Health information was collected from 1,590 household members via in-person interviews. Results: Participants in households with quantified SO2, NO2, and H2S (i.e., with measured concentrations above the limit of quantification) were twice as likely to report doctor-diagnosed asthma. Participants in homes with quantified SO2 were more likely to report wheezing symptoms {ever wheezing, prevalence odds ratio [POR] 1.79 [95% confidence interval (CI) 1.05, 3.05]; speech-limiting wheeze, POR 3.53 (95% CI: 1.06, 11.74)}. NO2 and H2S were similarly associated with wheezing symptoms. Quantified HCHO was associated with neurologic symptoms (difficulty concentrating POR 1.47; 95% CI: 1.02, 2.13). Burning incense daily was associated with increased headaches (POR 1.87; 95% CI: 1.09, 3.21), difficulty concentrating (POR 3.08; 95% CI: 1.70, 5.58), and forgetfulness (POR 2.68: 95% CI: 1.47, 4.89). Conclusions: This study provides new information regarding potential health risks from pollutants commonly found in indoor environments in the UAE and other countries. Multipollutant exposure and health assessments in cohort studies are needed to better characterize health effects of indoor air pollutants.

Dust Generation from Handling Powders in Industry

This article explores the hypothesis that the amount of dust generated by an industrial process that handles granular material depends on (a) the size distribution of the granules and (b) the ratio of impaction to cohesion. Here, impaction characterizes particle separation forces caused by energy input from the process, and cohesion characterizes interparticle binding forces within the material itself. A mathematical model based on this hypothesis is presented and evaluated using 441 data sets from an industrial-scale apparatus designed to measure dust generation. Dust generation was characterized in experiments using titanium dioxide, limestone, glass beads, and lactose with moisture contents ranging from 0% to 6% and size distributions of d 25 µm in aerodynamic diameter, dropped from heights of 0.25, 0.7, and 1.25 m at material flows of 0.1, 0.3, and 0.6 kg/sec. Results are presented in equations for impaction, cohesion, and dust generation as a function of particle size. The equa...

EXPERIMENTAL EXAMINATION OF FACTORS THAT AFFECT DUST GENERATION

A method is presented to examine factors that affect the amount and size distribution of dust generated by falling granular material in still air. This work was conducted by using an apparatus with separate dust generating and dust measuring sections. The dust generated by a falling material was carried into an elutriation column equipped with a slotted Sierra high-volume impactor at the top. This apparatus can measure dust generation rates for particles between 0.4 and 25 microns in aerodynamic diameter as well as the amount of air entrained by the falling material. Four granular materials were tested, and a simple model was developed to describe the dust generation rate of these materials as a function of particle size, drop height, material flow, and moisture content. Moisture content strongly influenced the interparticle binding forces and the amount of dust generated. Drop height and material flow influenced the material separation forces and also significantly influenced the amount of dust generated.

Laboratory Measurements of Oil Mist Concentrations Using Filters and an Electrostatic Precipitator

This study investigated the potential for mineral oil mist to evaporate, during sampling, from filters and electrostatic precipitator substrates used to assess personal exposure. If sample evaporation occurs, reported mist concentrations will underestimate true exposure. Mineral oil used as a machining fluid is not normally considered volatile; however, when dispersed as mist its aggregate surface area is so high that significant evaporation can occur. National Institute for Occupational Safety and Health Method 5026 specifies that oil mist concentrations should be determined by collecting mist on filters of mixed cellulose esters (MCE) or polyvinyl chloride (PVC). Collected mist droplets remain dispersed on the filter surface and in contact with passing air while sampling continues, conditions that can lead to sample evaporation. Less evaporation should occur for samples taken with an electrostatic precipitator, where mist droplets are separated from the airflow by electrostatic force and coalesce on the precipitator wall to form a film with relatively low surface area. Collection of mineral oil mist was investigated using a precipitator designed for personal sampling and using either an MCE or a PVC filter. The amounts of oil mist collected using the precipitator were significantly higher than the amounts collected using the filters, p < 0.001. Further tests in which clean air passed through mist-loaded precipitators and filters showed that the precipitator retained substantially more collected mist than both filters, p < 0.001, and further suggested that the MCE filter retained more mist than the PVC filter, p = 0.059. Differences in sample collection and retention between the precipitator and the filters were particularly pronounced at mist loadings below 1 mg.

Oil mist concentration : A comparison of sampling methods

Discrepancies arise when sampling mineral oil mist using a glass fiber filter, a polyvinyl chloride filter, a polytetrafluoroethylene filter, an electrostatic precipitator, and two light-scattering devices. Most gravimetric methods show discrepancies because mist droplets, which have a high surface area, evaporate from the filters during sampling. Inconsistencies occur with light-scattering devices because these instruments are sensitive to particle size distributions, shapes, and refractive indices. Results from laboratory and field experiments show that concentrations measured using these methods vary by factors of two to five. Discrepancies were greatest when oil mist concentrations were relatively low.

Performance of Industrial Equipment to Collect Coolant Mist

A protocol was developed to evaluate collector performance in the laboratory under conditions that simulate plant practice. Eight collector manufacturers provided nine samples of their products, each designed to handle 1700 m3/hr (1000 ft3/min) of airflow. Each collector was tested using mists of mineral oil, soluble oil, and synthetic fluid; for a three-stage collector, tests with each metalworking fluid lasted for thirteen 24-hour days. For each collector stage as well as for each assembled collector, tests established the relationship between efficiency and droplet diameter for droplets from less than 0.3 to about 6 µm in diameter. Substantial differences in efficiency and pressure drop were found among the stages and assembled collectors. Some metal mesh filters worked well as first stages, whereas pocket filters, one cartridge filter, and an electrostatic precipitator worked well as second stages. High-efficiency particulate air (HEPA), 95% dioctyl phthalate (DOP), and candle filters provided excelle...

Volatilization of Mineral Oil Mist Collected on Sampling Filters

Abstract Exposure to mineral oil mist has been associated with the development of asthma, dermatitis, lipid pneumonia, and cancers of the digestive tract. The National Institute for Occupational Safety and Health analytical method for sampling mineral oil mist specifies collection on filters. In this study, mineral oil mist collection on glass fiber and polyvinyl chloride filters was examined to determine if significant quantities of mineral oil volatilize from filters after collection. Evaporative loss from an electrostatic precipitator was also examined. Filters were placed in an oil mist loading chamber and rapidly loaded with oil mist. Both fresh and used mineral oil were employed. The filters were removed from the chamber and weighed to determine the mass of oil loaded on the filter. After clean air was drawn through the filters for 4 hours, the filters were reweighed to determine the mass of oil lost to evaporation. A similar procedure was followed for the electrostatic precipitator. Fresh mineral o...

Mist Concentration Measurements II: Laboratory and Field Evaluations

Sampling methods to determine occupational exposures to metalworking fluid mists are subject to bias. Light-scattering devices may respond differently to variations in particle size, shape, and refractive index. Gravimetric samplers are prone to evaporative losses of semi-volatile components. The performance of two light scattering devices, an electrostatic precipitator, and filters followed by gravimetric analysis was investigated when measuring metalworking fluid mist in laboratory and field settings. Laboratory tests with soluble oil and field tests with soluble oil, straight oil, and semi-synthetic fluid showed significant evaporative losses from filters. Light-scattering devices tended to overestimate mist concentrations when mass median diameters were less than about 2 microns and to underestimate mist concentrations when mass median diameters were larger. Filters will underestimate occupational exposures to metalworking fluid mists when semi-volatile components are present.

Passive Sampler for PM10–2.5 Aerosol

Abstract This study investigates the use of a small passive sampler for aerosol particles to determine particulate matter (PM)10–2.5 concentrations in outdoor air. The passive sampler collects particles by gravity, diffusion, and convective diffusion onto a glass coverslip that is then examined with an optical microscope; digital images are processed with free software and the resultant PM10–2.5 concentrations determined. Both the samplers and the analyses are relatively inexpensive. Passive samplers were collocated with Federal Reference Method (FRM) samplers in Chapel Hill, NC; Phoenix, AZ; and Birmingham, AL; for periods from 5 to 15 days. Particles consisted primarily of inorganic dusts at some sites and a mix of industrial and inorganic materials at other sites. Measured concentrations ranged from <10 µg/m3 to ∼40 µg/m3. Overall, PM10–2.5 concentrations measured with the passive samplers were within ∼1 standard deviation of concentrations measured with the FRM samplers. Concentrations determined with passive samplers depend on assumptions about particle density and shape factors and may also depend somewhat on local wind speed and turbulence; accurate values for these parameters may not be known. The degree of agreement between passive and FRM concentrations measured here suggests that passive measurements may not be overly dependent on accurate knowledge of these parameters.

Conducting Environmental Health Research in the Arabian Middle East: Lessons Learned and Opportunities

Background: The Arabian Gulf nations are undergoing rapid economic development, leading to major shifts in both the traditional lifestyle and the environment. Although the pace of change is brisk, there is a dearth of environmental health research in this region. Objective: We describe challenges and successes of conducting an environmental epidemiologic study in the United Arab Emirates (UAE), a Gulf nation in the Middle East, with an inter-disciplinary team that includes in-country academic and government collaborators as well as U.S. academic collaborators. Discussion: We present several issues, including study and data collection design, exposure assessment, scheduling and time coordination, quality assurance and quality control, and institutional review board protocols. These topics are considered in a cultural context. Benefits of this research included building linkages among multinational, interdisciplinary team members, generating data for local environmental decision making, and developing local epidemiologic research capacity. The Middle Eastern culture of hospitality greatly benefited the project team. Conclusion: Cultural differences impact multiple aspects of epidemiologic research and should be respectfully addressed. Conducting international population-based environmental research poses many challenges; these challenges can be met successfully with careful planning, cultural knowledge, and flexibility. Lessons learned are applicable to interdisciplinary research all over the world. The research conducted will benefit the environmental and public health agencies of the UAE and provide the nation’s leadership with country-specific environmental health data that can be used to protect the public’s health in a rapidly changing environment.