Chemical Characterizations of Contaminants in Indoor Environments: Sampling and Analysis

Chemical Characterizations of Contaminants in Indoor Environments: Sampling & Analysis

Tuesday, June 2, 2015, 10:30 AM - 12:30 PM

CS-111-01 A Novel Method for Determining Chemical Residues from Fire and Smoke in Indoor Air

A. Delia, K. Martin, Prism Analytical Technologies, Inc., Mt. Pleasant, MI; D. Baxter, Environmental Analysis Associates, Inc., San Diego, CA

Situation/Problem: The particulate and chemical residues from fire and smoke events can pose a significant challenge for air quality professionals in terms of the possible aesthetic,​​ health, and odor aspects, particularly in determining the level of remaining contamination during and after cleanup. The complexity of the particulate and chemical residues makes identification of the components specific to the fire difficult. Traditional methods are complicated by secondary sources and do not typically address the issue of the characteristic smoky odor that often lingers for months, or even years, or the potential health hazards of the chemical residue.

Resolution: A new method using thermal desorption gas chromatography-mass spectrometry (TD GC-MS) for determining the presence of chemical residues from fire and smoke by examining select volatile organic compounds (VOCs) has been developed. These VOCs were determined based on laboratory and situational studies of a variety of materials exposed to fire and smoke as well as an extensive literature review. This method reveals the extent of chemical contamination from fire and smoke events in indoor air and can be used to assess the potential health and odor effects. Together, this VOC analysis of chemical residues and the more traditional microscopy analysis of soot, char, and ash, provide a more comprehensive solution in determining the level of contamination from fire and smoke events.

Results: Several VOCs were evaluated for their efficacy as fire and smoke indicators for both structural and wild fire events. VOCs were selected based on their prevalence in multiple fire situations, lack of additional potential sources, and ease of analytical identification. The selected VOC fire and smoke indicators were tested in several real fire and smoke events and were used to evaluate the extent of contamination.

Lessons Learned: Fire produces a complex mixture of chemicals with a variety of characteristics that influence the effects of the fire upon its surroundings. Since the fire and smoke residues add to the existing mix of chemicals, determining the source of the specific chemical compounds can be challenging. A comprehensive understanding of these potential sources is critical to separating the effects of the fire and smoke from the other sources.

SR-111-02 A Comparison of Canisters and Solid Sorbent Tubes for Air Sampling of Volatile Organic Compounds in Indoor Environments for 14 to 21 days

A. Rossner, Clarkson University, Potsdam, NY

Objective: This research focused on the evaluation of evacuated canister coupled with the capillary flow controllers to collect volatile organic compounds (VOCs) for sampling periods ranging from 14 to 21 days using an exposure chamber. This research is being done to evaluate the effectiveness of sampling indoor environments for vapor intrusion chemicals as well as other indoor contaminates that may cause long term health effects. Evacuated canisters have been used for many years to collect ambient air and indoor air samples. There are several benefits of using canisters over other sampling methods, including the ability to analyze multiple sub-samples from a single canister sample and the ability to directly and cost-effectively analyze the samples without the need for toxic or expensive extracting solutions. 

Methods: Using a capillary flow control device designed to provide extremely low flow rates (ranging from 0.05 to 1.0 mL/min) VOC (specifically, BTEX and Perchloroethylene) samples were collected over an extended period of time. Six replicate canister samples and six diffusion tube samples were collected for each of the 6 experiments in a chamber for time periods for up to 3 weeks. Concentrations ranging from 0.05 to 0.5 of the TLVs were evaluated. All analysis was conducted using a GC/FID. The sorbent tubes were thermo desorbed and analyzed on GC/FID. The chamber was connected to an on-line GC and this data was used as the “gold standard” for the challenge concentrations. 

Results: The results indicate that the capillary-canister precision and accuracy exceeded that of the sorbent methods. Long-term sampling with the small evacuated canisters was found to provide results statistically more accurate (p<0.5) than sorbent sampling methods. In addition, the canister method allowed for significant increase in sampling time and allows for the collection of a broader range of VOCs. 

Conclusions: A canister coupled with a capillary flow controller can provide for long-term sampling in indoor air quality assessments for low levels of VOCs and support new exposure assessment strategies for contaminants from inside and outside the buildings.

SR-111-03 Representativeness of Single-Point Sampling for Estimating Residential Indoor Air Temperature and Relative Humidity

J. Johnston, B. Magnusson, D. Eggett, Brigham Young University, Provo, UT; S. Collingwood, University of Utah, Salt Lake City, UT; S. Bernhardt, Utah State University, Logan, UT

Objective: Residential air temperature and relative humidity (RH) are important determinants of human comfort and health, and accurate assessment of indoor environmental conditions is necessary to properly characterize exposure. Studies commonly use instantaneous single-point measures collected with handheld (pen-type) thermo-hygrometers to estimate indoor temperature and RH, but there is little evidence to support using this sampling strategy to represent longer-term residential exposures. This study evaluated the relationship between single-point and continuous sampling methods over two exposure periods (30 min and 12-day).

Methods: Study homes (N = 9) were recruited from among employee volunteers at the Cache County national children’s study center in Logan, Utah. Continuous data-logged sampling was conducted in each home for 2–3 weeks from March–June 2012. Instruments were placed in a main living area of the home. While continuous monitors were operating in the home, simultaneous single-point measures (n = 114) were collected in the same room on multiple days and at different times using handheld thermo-hygrometers.

Results: Time-centered single-point measures were moderately correlated with short-term (30 min) data logger means for air temperature (r = 0.76) and RH (r = 0.70). Single-point air temperature was also moderately correlated with data-logger 12-day means (r = 0.64). Single-point measures were weakly correlated with data logger 12-day RH (r = 0.53). Of the single-point RH measures, 59(51.8%) deviated more than +/- 5%, 21(18.4%) deviated more than +/- 10%, and 6(5.3%) deviated more than +/- 15% from data logger 12-day means.

Conclusions: The strength of the relationship between single-point sampling and continuous monitoring decreased rapidly as exposure time intervals were increased. This finding was more pronounced for RH than for air temperature. These data suggest that single-point sampling, particularly for assessing residential RH, may lead to home misclassification when used as either a direct measure or as a surrogate for the presence of other indoor exposures such as mold or house dust mites. Continuous indoor monitoring is recommended for use in studies where air temperature and RH exposures are evaluated for health effects.

SR-111-04 Characterization of Malodors from a Polymethyl Methacrylate Roof Membrane System

J. Kominsky, Environmental Quality Management, Inc., Cincinnati, OH

Objective: This study determined whether the source of malodors characterized by building occupants as “chemical-, fecal-, and/or barnyard-like” was associated with emissions from a recently installed polymethyl methacrylate (PMMA) roof membrane system.

Methods: Three samples of roof membrane were analyzed to identify the headspace volatile organic compounds (VOCs). A portion of each sample was placed in a 1-liter glass chamber that was purged with ultra-pure air, sealed, and maintained at 46oC for 24 hours to equilibrate the headspace. An aliquot of the headspace was analyzed for VOCs using EPA Methods TO-15 and TO-17. Fixed-station area samplers were positioned at rooftop air intakes and in areas of the building with reported incidents of malodors to determine whether the identified compounds entered the building. Six pairs of samplers were positioned. Each sampler pair consisted of a 6-liter stainless steel canister with a 72-hour flow controller, and a tandem thermal desorption tube with Swagelok® fittings attached to a constant-flow vacuum pump operating at 25 ml/min. Samples were collected over 5 days (6:00 am to 6:00 pm). Fixed-station air samples were collected at HVAC evaporator coils to test for carboxylic acids known to have “fecal-like” and/or rancid odors to determine whether the malodors were emanating from wet organic debris (biofilm) on the coils.

Results: Headspace analysis showed similar emission profiles. Quantitatively methyl acrylate > 2-ethyl hexyl acrylate > benzene > trimethylbenzenes > toluene > 4-ethyltoluene > n-Propyl benzene > naphthalene > 1-methylnaphthalene >2-methyl naphthalene. Benzene, naphthalene, methylnaphthalenes, toluene, trimethylbenzenes, and other compounds were consistently present at rooftop air-intakes and in the building tenant space; this demonstrate that emissions from the PMMA roof membrane are entering the building. Qualitatively the results are similar to the headspace analysis of roof membrane samples completed by the manufacturer’s consultant, which includes compounds (p-cresol, 1- and 2-methylnaphthalene, and naphthalene) with odors characterized as fecal- or barnyard-like, musty, and/or naphthalenic. Carboxylic acids were not detected.

Conclusions: The malodor reported by building occupants appears to have resulted from the PMMA roof membrane emissions entering the building via rooftop air-intakes. Carbon-filtration units in air-intakes operated until the malodors subsided over time.

SR-111-05 Particulate and Chemical Emissions from 3-Dimensional Printers

A. Stefaniak, M. Duling, R. LeBouf, NIOSH, Morgantown, WV; J. Yi, T. Nurkiewicz, West Virginia University, Morgantown, WV

Objective: Three-dimensional (3-D) printers use a heated nozzle to melt a solid thermoplastic filament and deposit multiple thin layers of extruded plastic to form a solid three-dimensional shape. The objective of this research was to evaluate factors which may influence the emission of particulate and chemicals from 3-D printers.

Methods: Real-time instrumentation was used to measure particle number, mass, size, and size distribution and total volatile organic compounds (TVOCs) and ozone. Evacuated canisters and gas chromatography were used to quantify specific VOCs. The influence of acrylonitrile butadiene styrene filament color on emissions was evaluated by printing a hair comb in natural, blue, red, and black on the same 3-D printer in a 500 L chamber. The effectiveness of controls was evaluated by measuring emissions with and without the manufacturer-provided printer cover in use.

Results: Filament color had a clear influence on particulate emissions. On a mass basis, maximum particle emissions [in µg m-3] were highest for natural (214±6), followed by blue (160±14), red (100±14), and black (9±2). Maximum particle number concentration [# m-3] and count median diameter [nm] also differed by filament color: red (3.8 x 1011; 50), natural (2.5 x 1011; 55), black (1.5 x 1011; 45), and blue (1 x 1011; 63). Peak TVOC levels followed the same rank order as mass concentration, i.e., natural (625±35), followed by blue (448±18), red (395±21), and black (165±21). Specific VOCs emitted were styrene, ethanol, and acetaldehyde. Ozone did not exceed background levels during testing. Removal of the printer cover resulted in a 24% increase in particle mass concentration and a doubling of particle number concentration but little change in TVOC levels.

Conclusions: 3-D printers may be important sources of ultrafine particles and VOCs in indoor manufacturing, office and home work environments. Users should be cognizant that emissions will be influenced by the choice of color filament. Particulate emissions will be reduced by use of the manufacturer-provided printer cover. Emission of ultrafine particles and styrene, a known asthmagen and neurotoxin, indicate the need for additional research on potential health effects from use of these printers and control technologies to reduce emission levels.

CS-111-06 Mercury Vapor Analysis of Cinnabar in Simulated Shipping Conditions by Atomic Fluorescence Spectroscopy

C. Altamirano, Arizona Instrument, Chandler, AZ

Situation/Problem: Cinnabar, also known as mercury sulfide (HgS), is a naturally occurring mineral ore, which has historically been used for its prominent red pigmentation in paints (vermillion) and cosmetics. Today, cinnabar is used to create elemental mercury by heating cinnabar in the presence of oxygen to create elemental mercury vapor. Although cinnabar is considered less toxic than elemental mercury, its toxicity is poorly understood in the context of ‘real world’ environments. Variables such as sun exposure, elevated temperatures, humidity and moisture may change the mercury vapor emissions of cinnabar and potentially create dangerous environments for employees.

Resolution: Using a portable atomic fluorescence spectroscopy mercury vapor analyzer, levels of mercury vapor emitted by cinnabar in simulated shipping environments can be reliably detected and measured. Using this form of analysis can be useful in verifying the safety of employees who are mining natural cinnabar, producing synthetic cinnabar, or are transporting cinnabar domestically or abroad.

Results: Results suggest that the two biggest factors in mercury vapor emission from synthetic cinnabar may be sunlight exposure and elevated temperatures. Sunlight exposure also transforms red cinnabar into black ‘metacinnabar’, which indicates a structural change in the crystalline structure. Humidity has little effect on the emissions, but when paired with elevated temperatures a greater signal is observed.

Lessons Learned: Synthetic Cinnabar emitted low levels of elemental mercury vapor at room temperatures and in a dry environment. Precautions should also be made to keep cinnabar in an inert gas such as nitrogen to prevent oxidation as well as storing it away from direct sunlight.​