Behzad Samimi

Evaluation of a real-time passive personal particle monitor in fixed site residential indoor and ambient measurements

Recent experimental findings in animals and humans indicate adverse respiratory effects from short-term exposures to particulate air pollutants, especially in sensitive subpopulations such as asthmatics. The relationship between air pollution and asthma has mainly been determined using particulate matter (PM) measurements from central sites. Validated tools are needed to assess exposures most relevant to health effects. Recently, a personal passive particulate sampler (personal Data-RAM, pDR, MIE Inc., Bedford, MA) has become available for studying personal exposures to PM with time resolution at 1 min. The pDR measures light scatter from PM in the 0.1–10 µM range, the significant range for health effects. In order to assess the ability of the pDR in predicting gravimetric mass, pDRs were collocated with PM2.5 and PM10 Harvard Impactors (HI) inside and outside nine homes of asthmatic children and at an outdoor central Air Pollution Control District site. Results are presented of comparisons between the HI samplers and the pDR in various modes of operation: passive, active, and active with a heated inlet. When used outdoors at fixed sites the pDR readings exhibit interference from high relative humidity (RH) unless operated with a method for drying inlet air such as a heater, or if readings at times of high RH are adjusted. The pDR correlates more highly with the HI PM2.5 than with the HI PM10 (r2=0.66 vs. 0.13 for outdoors, r2=0.42 vs. 0.20 for indoors). The pDR appears to be a useful tool for an epidemiologic study that aims to examine the relationship between health outcomes and personal exposure to peaks in PM.

Exposure of Acrylic Fingernail Sculptors to Organic Vapors and Methacrylate Dusts

Personal and area samples for organic vapors and polymethacrylate dust were collected in six different sculptured nail salons. Self-administered symptom questionnaires were completed by 20 female nail sculptors and 20 matched controls. Mean time-weighted average concentrations (TWACs) of ethyl methacrylate, isopropyl alcohol, butyl acetate and toluene in 17 personal organic vapors samples collected in these establishments were 4.5, 15.6, 0.4 and 0.8 ppm, respectively. The mean TWACs of polymethacrylate dust in 16 personal samples were 0.9 mg/m3 and 1.4 mg/m3 for respirable dust and total dust, respectively. The only statistically significant (p less than .05) health effect noted among sculptors was throat irritation. Also, nose and skin irritation, drowziness, dizzy spells and trembling of the hands were reported consistently more often by sculptors than the control group; however, the difference was not statistically significant.

Evaluation and quality control of personal nephelometers in indoor, outdoor and personal environments

Personal nephelometers provide useful real-time measurements of airborne particulate matter (PM). Recent studies have applied this tool to assess personal exposures and related health effects. However, a thorough quality control (QC) procedure for data collected from such a device in a large-scale exposure assessment study is lacking. We have evaluated the performance of a personal nephelometer (personal DataRAM or pDR) in the field. We present here a series of post hoc QC procedures for improving the quality of the pDR data. The correlations and the ratios between the pDRs and the collocated gravimetric measurements were used as indices of the pDR data quality. The pDR was operated in four modes: passive (no pump), active (with personal sampling pumps), active with a heated inlet, and a humidistat. The pDRs were worn by 21 asthmatic children, placed at their residences indoors and outdoors, as well as at a central site. All fixed-site pDRs were collocated with Harvard Impactors for PM2.5 (HI2.5). By examining the differences between the time-weighted average concentrations calculated from the real-time pDRs’ readings and recorded internally by the pDRs, we identified 9.1% of the pDRs’ measurements suffered from negative drifts. By comparing the pDRs’ daily base level with the HI2.5 measurements, we identified 5.7% of the pDRs’ measurements suffered from positive drifts. High relative humidity (RH) affected outdoor pDR measurements, even when a heater was used. Results from a series of chamber experiments suggest that the heated air stream cooled significantly after leaving the heater and entering the pDR light-scattering chamber. An RH correction equation was applied to the pDR measurements to remove the RH effect. The final R2 values between the fixed-site pDRs and the collocated HI2.5 measurements ranged between 0.53 and 0.72. We concluded that with a carefully developed QC procedure, personal nephelometers can provide high-quality data for assessing PM exposures on subjects and at fixed locations. We also recommend that outdoor pDRs be operated in the active mode without a heater and that the RH effect be corrected with an RH correction equation.

Organic Vapors at Underground Gasoline Tank Removal Sites

Abstract Leaking underground fuel storage tanks are a major public health concern of the 1980s. The discovery of these leaking tanks and the potential for groundwater contamination prompted legislation which requires monitoring of existing tanks and removal of those tanks found leaking. In San Diego County, the removal of an underground storage tank is witnessed by a Hazardous Materials Specialist (HMS). The HMS and the tank contractor (TC) who actually conducts the tank removal are both subject to exposure to organic vapors during this work activity. To investigate the organic vapors at gasoline tank removal sites, breathing zone and general air samples are collected on large (400/200 mg) charcoal tubes. Breathing zone samples were collected for both HMSs and TCs. General air samples were collected upwind and downwind from the site, three meters deep in the excavation and directly above the excavation at grade. Five gasoline tank removal sites were sampled. The samples were analyzed for pentane, n-hexane...

Analysis of Volatile Chemicals in the Workplace by Fourier Transform Infrared Spectroscopy

Abstract Fourier transform infrared (FTIR) instrumentation was evaluated to determine if it has the capability to singly monitor mixtures of volatile organic chemicals (VOCs) at or below their threshold limit value. The system investigated to monitor work sites for the presence of VOCs was the Perkin-Elmer 1760x Fourier Transform Infrared Spectrometer equipped with a 20-meter Wilks/Foxboro gas cell. Six different work areas were chosen for this study: a photography lab, a dry-cleaning establishment, surgical operating rooms in a vivarium, a histology lab, a paint stripping shop, and a paint spraying facility. The contents of workplace air samples collected in Teflon™ bags were identified by matching FTIR sample spectra against known VOC spectra stored in a computerized library and by manual spectral comparisons. The FTIR monitoring of the workplace air samples identified single volatile components in the photography laboratory (acetic acid), and the two medical operating rooms (forane, halothane). Air sam...

Comparison of Standard Charcoal Tubes With Abcor (NMS) Gasbadges Within Controlled Atmosphere

Standard charcoal tubes were compared with Abcor (NMS) Gasbadges to sample different concentrations of styrene, ethyl acrylate, and n-butyl acrylate at different air velocities. Air velocities of 0.22 and 0.44 m/sec in a direction perpendicular to the dosimeters suface were investigated. Desorption efficiency from badges was consistently higher than from charcoal tubes for all three monomers. Correction factors for charcoal tubes and badges for each sampling condition were calculated. There were no significant differences among the correction factors for charcoal tubes collected at various concentrations and air velocities. The differences were also insignificant among the correction factors of badges collected at different concentrations but at same air velocity; however, the correction factors for badges were significantly different under the two experimental air velocities, i.e., they were consistently above 1.0 at 0.22 m/sec. and below 1.0 at 0.44 m/sec. Establishment of a series of correction factor...

Extent of Fungal Growth on Fiberglass Duct Liners with and without Biocides Under Challenging Environmental Conditions

Eight brands of fiberglass duct liners, including three that contained biocides, were exposed to challenging environmental conditions that would promote fungal growth. Twenty-four rectangular sheet metal ducts in three groups of eight ducts per group were lined with the eight selected liners. Each group of ducts was exposed to one of the three test conditions within an environmental chamber for a period of 15 days. These conditions were a) 75 percent RH, b) 75 percent RH plus water spray, c) 75 percent RH plus dry nutrient, and d) 75 percent RH plus water plus nutrient. Viable spores of Aspergillus niger were aerosolized into each duct as seed. On the 16th day, air and surface samples for fungal spores were collected from inside ducts. The results of air sampling using N6 sampler and visual inspection indicated that two out of three biocide-containing liners, Permacote and Toughgard, inhibited fungal growth but only under condition A. The third biocide-containing liner, Aeroflex Plus, was effective even when it was wet (conditions A and B). All three biocide-containing liners failed to inhibit fungal growth under conditions C and D. Among the five other types of liners that did not contain biocides, ATCO Flex with a smooth Mylar coating was more preferable, exhibiting lower fungal activity during conditions A, B, and C. All liners failed under condition D when nutrient and water were added together. Surface sampling using adhesive tape failed to produce representative results, apparently due to rough/porous surface of duct liners. It was concluded that duct liners with biocide treatment could be less promoting to microbial growth under high humidity as long as their surfaces remain clean and water-free. A liner with an impermeable and smooth surface seems to be less subject to microbial growth under most conditions than biocide-containing liners having porous and/or rough surfaces.

Laboratory Evaluation of RDM-201 Respirable Dust Monitor

The current paper discusses the results of laboratory experiments conducted to evaluate the GCA Respirable Dust Monitor RDM-201 in comparison with the standard Gravimetric Respirable Dust Sampler (GRDS). The samplers were compared in parallel within the atmosphere of an inhalation chamber laden with Arizona Fine Road Dust (AFRD). A wide range of dust concentrations (i.e., from 0.17 to 32:81 mg/m3) was used in the experiments. Sampling time varied from 15 to 120 min. There was a high agreement between the two GRDSs, particularly for samples with dust weight larger than 0.5 mg. The correlation and linearity between the RDM-201 display reading and the actual weight of dust on the instruments filter were quite high for dust samples larger than 0.5 mg, but dropped significantly for samples less than 0.5 mg. Considering the extremely high dust concentration required to collect a minimum of 0.5 mg of respirable dust within 1-min sampling time of the RDM-201s automatic sampling mode, it was concluded that the use of automatic mode intended for quick evaluation of dusty atmosphere is impractical under most ordinary dusty conditions. The RDM-201 manual mode can be used, however, as reliably as a GRDS, for extended sampling times for assessment of TWAC of respirable dust in the atmosphere of a workplace, providing that a minimum of 0.5 mg sample is collected on the filter.