Chemical and Physical Aspects of Exposures in the Built Environment


Tuesday, May 24, 2016, 10:30 AM - 12:30 PM


Indoor Air Monitoring​ in Day-Care Centers

Y. Yen, Kaohsiung Medical University, Kaohsiung, Taiwan

Objective: the aim of this study is to monitor the airborne influenza A and B virus in two day-care centers with different ventilation form

Methods: Environmental monitoring was from August 2006 to January 2007. Day care center A was near a busy traffic street and had natural ventilation and air conditioning. Center B had only an air-conditioning system and was located in a small lane. The sampling parameters are as follow: the concentration of bacteria and fungus, influenza virus in the air, indoor meteorological factors, particle numbers, CO and CO2. The seasonal variation was also investigated (Summer, Fall and Winter) to evaluate the relation between the concentration of airborne pathogen and occurrence of respiratory infections.

Results: Airborne influenza A and B virus were both successfully quantified from the two centers by filter and real-time qPCR. The mean concentration of 179 samples of influenza A and B virus is 8.03x104 copy/m3 and 1.59x105 copy/m3. The average of influenza A virus is significantly higher in summer (p =0.019). The positive rate of influenza A and B virus is 29% and 53%.

Conclusions: Comparing different ventilation system from two centers, the air contaminant: total cultivable bacteria, CO and CO2 concentration: center A > center B (p <0.01). The positive rate of influenza A and B virus: B>A (p <0.05). The mechanical exhaust system with less fresh air of center B might be the reason.



Formaldehyde Emissions from Small Chamber Testing of Laminate Flooring and Comparison to Exposure Modeling

J. Lotter, K. Unice, P. Ruestow, A. Abelmann, H. Fritz, E. Beckett, J. Bare, and J. Pierce, Cardno ChemRisk, Chicago, IL

Objective: It has long been understood that composite wood products may release airborne formaldehyde. As such, the California Air Resources Board (CARB) has set limits on formaldehyde emissions from composite wood products. The purpose of our investigation was to determine (1) how chamber test emission results from two products labeled as CARB Phase 2 compliant compared to the emissions standards in the Airborne Toxic Control Measure (ATCM) and (2) if the predicted steady-state airborne concentrations based on small chamber testing were consistent with the measured concentrations following the installation of these products.

Methods: Samples of two laminate flooring products (Products 1 and 2) were evaluated in accordance with the ASTM D6007 small chamber testing method. Each product was analyzed using CARB comparative and deconstructive testing protocols. The results of the tests were compared to the emission standards for hardwood plywood with a composite core [HWPW-CC] (0.05 ppm) and medium density fiberboard [MDF] (0.11 ppm), respectively. Predicted steady-state room air concentrations were determined using the small chamber CARB comparative test results. In addition, both products were installed in separate study rooms and 24-hr diffusive badge samples (n = 48) were collected over the course of 35 days. Predicted steady state formaldehyde concentrations were compared to the concentrations measured on post installation day 35, as it was determined that steady state was not reached in either study room.

Results: Based on CARB comparative testing, the concentrations for Products 1 and 2 were 0.018 ppm and 0.012 ppm, respectively. However, using CARB deconstructive testing, the concentrations were 0.420 ppm and 0.106 ppm. Results for Product 1 exceeded the emission standard for MDF by nearly 4-fold, and Product 2 was within 5% of the standard. The predicted steady-state concentrations were approximately 4- to 5-fold lower that the actual concentrations measured in the study rooms on post-installation day 35.

Conclusions: We found that certain flooring products labeled as CARB Phase 2 compliant may be classified as exceeding the CARB Phase 2 emissions standards for MDF based on deconstructive testing. Furthermore, using accepted modeling techniques designed to provide conservative estimates of room air concentrations, the modeled concentrations were considerably lower than actual measured concentrations.



Air Corrosivity Monitoring in Museums

E. Light and R. Gay, Building Dynamics, LLC, Ashton, MD; C. Grzywacz and C. Hawks, National Gallery of Art, Washington, DC; K. Horiuchi, ALS Global, Simi Valley, CA; K. Makos, Research Collaborator, Smithsonian, Washington, DC

Objective: Corrosion of museum collections caused by air contaminants is a major concern. The authors compared several monitoring methods for use in screening materials for museum displays and tracking air corrosivity in museums.

Methods: A pilot project was conducted in a museum to compare several methods for assessing air for corrosive agents. Exposure to carboxylic acids and aldehydes emitted by wood products was of particular interest. Side by side measurements were made by active sampling (sorbent tubes), passive sampling (acid strips and diffusion tubes) and copper probes quantifying overall air corrosivity.

Results: Data are presented from samples collected in various display cabinets and museum HVAC zones.

Conclusions: Pros and cons of alternative sampling methods are presented. Recommendations are made for development of air corrosivity assessment protocols for screening wood emissions from museum display cabinets and tracking ambient air quality in museums.



Assessment of Indoor Formaldehyde Concentrations Following the Installation and Removal of Laminate Flooring

J. Pierce, A. Abelmann, P. Ruestow, J. Lotter, E. Beckett, and H. Fritz, Cardno ChemRisk, Chicago, IL; J. Bare and K. Unice, Cardno ChemRisk, Pittsburgh, PA

Objective: Concerns have been raised regarding formaldehyde emissions from laminate flooring. Given the limited sampling data available, an investigation of the potential formaldehyde emissions resulting from the installation, use, and removal of laminate flooring was conducted.

Methods: Two laminate flooring products were purchased and installed in separate study rooms. Passive 24-hr diffusive badge samples (n = 79) for formaldehyde were collected over 63 days during: a preinstallation period, an acclimation period (packaged products stored in the study rooms), and installation and removal. The concentrations were compared to exposure limits and guidelines that exist in the U.S. for indoor air.

Results: Mean background concentrations were 0.006 ppm and 0.005 ppm in Rooms 1 (R1) and 2 (R2), respectively. During acclimation, mean concentrations increased to 0.009 ppm and 0.010 ppm in the two rooms, respectively. Mean concentrations following the installation of the flooring were 0.038 ppm (range: 0.020-0.058 ppm) in R1 and 0.022 ppm (range: 0.013-0.039 ppm) in R2; these concentrations were statistically significantly higher than background (p < 0.001) and acclimation concentrations (R1: p < 0.001; R2: p = 0.011). Upon removal of the flooring, concentrations decreased rapidly and, on post-removal day 7, were not statistically significantly elevated compared to background. Throughout the study (including prior to and during acclimation), mean airborne concentrations exceeded the 8-hr and chronic Reference Exposure Level (REL) of 0.007 ppm and the Proposition 65 No Significant Risk Level (NSRL) of 40 µg/day (24-hr equivalent: 0.002-0.003 ppm) set by California’s Office of Environmental Health Hazard Assessment (Cal-OEHHA). Following the installation of the flooring, the Federal Emergency Management Agency (FEMA) procurement standard (0.016 ppm) was also exceeded in both rooms.

Conclusions: Formaldehyde was detected in indoor air at levels that exceeded background during the acclimation of the products, following flooring installation, and up to 7 days following removal. Concentrations resulting from the use of both products exceeded nonoccupational indoor air exposure limits and guidelines in the U.S during all study periods.



A Review of the Health Effects of MVOCs

H. Burge, EMLab PK, San Bruno, CA

Situation/Problem: Microbial volatile organic compounds (MVOCs) are produced by bacteria and fungi during food digestion. MVOCs are not unique to microbes, nor are any specific to any one species. Hundreds of MVOCs have been identified, including 3-methylbutan-1-ol, 3-methylbutan-2-ol, fenchone, heptan-2-one, hexan-2-one, octan-3-one, octan-3-ol, pentan-2-ol, α-terpineol, and thujopsene. Many occupants of moldy buildings detect these MVOCs and worry about health effects of the mold or of the VOCs.

Resolution: Some sampling has been done to document concentrations of various MVOCs in some environments. These studies have used varying methods both of sampling and analysis. At least one study of odor thresholds has been done, and several laboratory and human exposure studies have been reported.

Results: There are few reports of measured concentrations of MVOCs. One investigator used a charcoal diffusion sampler over 4 weeks and found four week averages in the range of 0.27-15.0 ug/m3. Mean total MVOCs in schools in Sweden were 423 ng/m3 indoors and 123 ng/m3 outdoors. The odors associated with these volatiles are often the first clue that microbial growth is occurring in a building. Odor thresholds for these compounds have not been well studied, but are apparently quite low. Many human factors, both physiological and emotional change odor perception. 1 -octen-3-ol which is a common volatile produced by many fungi has an odor threshold of 200 ng/m3. In lab studies embryonic stem cells have been exposed to 1-octen-3-ol. 50% inhibition concentrations were in the range of 98 and 258 ppm. The concentration capable of decreasing the respiratory frequency of mice by 50% (i.e., the RD(50) of 1-octen-3-ol, 3-octenol, and 3-octanone were 182 mg/m3, 1,359 mg/m3 and 17,586 mg/m3 respectively. In human chamber studies, 29 volunteers were exposed to 3-Methylfuran (a common fungal volatile) at concentrations of 1mg/m3. There were no subjective symptoms at this concentration but there were some significant physiological changes. In epidemiological studies, some health associations with MVOCs have been noted. In Sweden, nocturnal breathlessness and doctor diagnosed asthma were associated with the higher levels of total MVOC measured. Mean levels of MVOCs were in the nanogram range. In another study, home symptoms in 4% of the study population were associated with 1-octen-3-ol.

Lessons learned: The question of whether or not MVOCs cause symptoms or illness in occupants of moldy buildings remains open. The existing literature leans toward the conclusion that odor perception is far below any possible irritation effect, as are measured concentrations in even moldy environments. However, there is some contradictory evidence, and more studies are needed.



Research Report: New "Green" Tracer for Measuring Air Movement in Buildings

C. Cooper, VERTEX companies, Kingston, NY

Objective: The current methods for measuring air movement and distribution in buildings all have drawbacks that make it difficult, expensive, time consuming, and require particular scientific expertise to carry out, and hence field testing of air distribution in buildings is rarely done. In 2015 the New York State Energy Research and Development Authority (NYSERDA) supported research to characterize the performance of a new air tracing technology (Cove) over varying distances, measurement times, materials interactions, air volumes, and tracer concentrations. The invention is an air measurement platform that enables air labeling and quantitation of a wide range of interactions using sensitive quantitative real-time measurement of a labeled air parcel.

Methods: Experimentation on COVE air tracer chemistry, method precision, and field applications included use of a small chamber test bed, and full scale building measurements. Data objectives included determining instrumental sensor detection sensitivities to tracer mixtures, multi-instrument precision, control of broadcast concentrations, lower detection limits, and safe operating parameters. Field experiments explored useful applications and limitations for this real-time rapidly deployed tracer release and measurement method, including applications for puff release of tracer, air velocity measurements, outdoor air ventilation air supply and exhaust efficiency, and determining indoor/outdoor mixing ratios, and duct leakage. A series of tests under ASHRAE Standard 129 methods for ventilation efficiency determination were completed at building scale under controlled conditions. Comparison measurements were made with blower door methods, and with tracer sulfur hexafluoride releases (SF6).

Results: Our experimental results of this new COVE tracer technology showed the ability to achieve scalable precise emitter control, parts per billion detection sensitivities, excellent repeatability of experimental results, and excellent multiple sensor precision with single point calibration, over recorded time scales of seconds to days.

Conclusions: This new tracing technology is shown to be a safe, relatively simple and reliable measurement method for field applications to accurately determine air leakage and airflow distribution in HVAC systems and in occupied ambient space. Envisioned applications for this new technology include field determination of ventilation effectiveness, and as a surrogate for precise quantitative measurement of an engineered system's ability to either contain, remove, or dilute chemical or biological contaminants.​