Grantee Research Project Results
1998 Progress Report: Longitudinal Studies of Indoor Air Quality in Office Buildings
EPA Grant Number: R825272Title: Longitudinal Studies of Indoor Air Quality in Office Buildings
Investigators: Batterman, Stuart A. , Franzblau, Alfred , Baker, Wayne
Institution: University of Michigan
EPA Project Officer: Chung, Serena
Project Period: July 1, 1997 through June 30, 2000 (Extended to June 30, 2002)
Project Period Covered by this Report: July 1, 1998 through June 30, 1999
Project Amount: $430,000
RFA: Air Quality (1996) RFA Text | Recipients Lists
Research Category: Air , Air Quality and Air Toxics
Objective:
This study addresses relationships between indoor air quality (IAQ), occupant health and comfort, and mitigation strategies. The major objectives are to relate direct measurements of IAQ to building-related illness (BRI) and sick building syndrome (SBS) and to increase the understanding of the relationships between occupant health, building system operation, and air quality.
The study uses a series of controlled interventions in large, mechanically ventilated office buildings with simultaneous measurements of IAQ parameters and surveys of occupant health and perception. The experimental interventions may include variations in fresh air exchange, ventilation rates, HVAC scheduling/operation, humidity, nighttime purge, filtration, and cleaning. A psychosocial survey accounts for job-related and personal cofactors that may affect reporting results of the IAQ and symptom survey. The blind, controlled and repeated measures design of the study is designed to provide high discriminatory power; experimental controls and carefully controlled interventions will minimize effects of confounding factors. Statistical analyses of survey results in conjunction with various indoor air quality indicators will adjust for confounding and will indicate controlling factors.
The study should help to identify and quantify effects of various indoor pollutants and potential mitigation strategies, and should help to improve protocols for building investigations.
Progress Summary:
Building Selection. Baseline monitoring began in the case study building, a six-story building (including an occupied basement) containing approximately 240 persons involved in clerical work. This building is connected to two other buildings (ISR-1 and ISR-3). It utilizes separate HVAC systems on each floor, which allow independent control of IAQ parameters on each floor. Planned interventions will adjust IAQ parameters on floors 2 and 4, and then on 3 and 5. The ground level floor differs from other floors in that it has greater occupant traffic leading to elevators and stairs, and its doors allow largely uncontrolled entry of outside air, dust, etc.; thus, this floor will not be examined.
IAQ Measurements. Systems to monitor IAQ were deployed and protocols refined. This included three self-contained real-time sensor arrays that were designed, built, and deployed on the 2nd, 3rd, and 5th floors to continuously measure seven indoor environmental parameters in fixed areas and systematically log the data into data files using laptop computer hardware and software. The seven parameters were light, sound, motion, carbon dioxide (CO2), relative humidity (RH), temperature, and total volatile organic compounds (TVOC). The sensor arrays were mounted on carts and thus could easily be moved from one location to another. In addition to the seven sensors listed, a vacuum supply was incorporated into the arrays so that integrated samples for volatile organic compounds (VOC) and respirable particulate matter smaller than 2.5 microns in aerodynamic diameter (PM2.5) also could be obtained. The sensor arrays were composed of three separate modules located on a mobile cart, namely, sensor module, support module, and a vacuum supply module. The sensor module consisted of a metal sheet to which the sensors and sensor electronics support board were fastened, surrounded by a protective plastic box with one side open to the environment. All sensors and sampling points were located towards the front, in close proximity to the opening facing outward. This module was placed on a support platform located 1.5 meters above the floor fastened to a vertical mast. An effective baffling system helped to reduce noise from the vacuum pump, and overall, the units were quiet and acceptable to building occupants.
Integrated samples for speciated VOCs were collected following the U.S. EPA TO-17 method for determination of volatile organic compounds in ambient air using active sampling onto sorbent tubes. A new GC-MS system with an automated thermal desorption system was obtained, and protocols developed for the TO-17 method. In brief, this involved low flow sampling using stainless steel sampling tubes packed with Tenax GC and Carbosieve. The protocol included the collection of duplicate samples at each of the three area monitoring sites on the 2nd, 3rd, and 5th floors, and one outdoor air site. The indoor air samples were taken at a height of 1.5 meters above the floor, located at the front of the sensor module. Outdoor air samples were taken at a location in the center of the intake grate of the 3rd floor HVAC system, just inside of the grate system, to provide protection from the elements. These samples were to be collected once per week during the study period, during working hours (approximately from 9 a.m. to 3 p.m.), at a sampling flow rate of 10 cc/minute to obtain a sampling volume of approximately 4 liters, as defined by the TO-17 method. On all days, duplicates and blanks were taken according to procedures outlined in the TO-17 method.
Particulate matter <2.5 µm was measured using preconditioned 37 mm Polytrak hydrophobic polyester membrane filters (Pall/Gelman, Ann Arbor, MI) and size-selective impactors (SKC PM2.5 impactor, 10 liter/minute operating flow rate. SKC Corp, Eighty Four, PA). The protocol included blanks on each sampling event. Airflow was the required 10 L/minute (± 0.16 L/second) flow. Because levels were quite low, 16-hour samples were collected from 8 a.m. to 5 p.m. on 2 consecutive mid-week days, usually on Wednesdays and Thursdays. Filters were conditioned and then weighed using a microbalance.
Bioaerosol measurement protocols were developed. In brief, sampling used a Standard Biotest RCS Centrifugal Air Sampler (Biotest Diagnostics Corp., Denville, NJ.) and three types of commonly used agars: Tryptic soy (TSA), Rose-Bengal (RBA) and DG-18 agars. TSA has a high water activity and provides a total count of molds, yeasts, and bacteria; RBA has a high water activity and employs Rose Bengal and streptomycin toxins to select for molds; and DG-18 has low water activity and employs glycerol dichloran and streptomycin toxins to limit the spread of fast-growing organisms, and is selective for xerophyllic bioaerosols that favor dry environments. The protocol developed took indoor samples at locations adjacent to the area sensor array sites; the outdoor air sampling site was located next to the ground floor air intake for the study wing of the building, at a level of approximately 1.5 m from the ground. Replicate samples were taken at one site to determine precisions.
Protocols to measure fibers were developed. Fiber data were collected following procedures in the National Institute for Occupational Safety and Health (NIOSH) Method 7400 "Asbestos and Other Fibers by PCM" (Phase contrast microscopy). In brief, field samples were to be obtained at each of the three area monitoring sites on the 2nd, 3rd, and 5th floors at a height of approximately 1.5 meters above the floor, located next to the sensor module. On the initial sampling dates, sampling took place on Wednesdays using personal sampling pumps (Dupont Constant Flow Sampler model P2500A or equivalent) and 25-mm cassettes with electrically conductive extension cowls and mixed cellulose esters (MCE) polymer membrane filters. Air flow was calibrated using a Gilian Gilibrator (model D800266. Gilian Instrument Corporation, W. Caldwell, NJ) to achieve 2.5 L/minute, which was determined to be sufficient to collect an acceptable number of fibers for accurate quantification. Sample preparation and fiber counting was performed according to NIOSH Method 7400, in which an area of approximately 25 percent of the filter was cut with a curved steel scalpel blade and mounted onto a glass microscope slide. The filter was cleared by placing the slide onto a hot (~70°C) metal block and exposing the slide to acetone vapor, after which a glass cover slip was mounted over the cleared filter. Fiber counting was accomplished using phase contrast microscopy and a Walton-Beckett type graticule. Per NIOSH recommendations for non-asbestos fibers, "B" counting rules were used.
Building performance data were collected from the pressure and temperature transmitters in the HVAC systems via the DDC network and imported in Excel spreadsheets. Parameters measured were temperatures in the supply, return, and mixed air plenums; supply and return airflow; and the mixed air damper position, as indicated by the pressure to the damper solenoid. Outdoor temperature and humidity, measured at a nearby location, also were recorded.
Occupant Survey. Several questionnaires will be administered to building occupants to gather information regarding (1) demographics; (2) medical history; (3) symptoms and perceptions, e.g., odors, irritants; and (4) psychosocial factors, e.g., information needed to construct a social network analysis. Both initial and follow-up questionnaires were revised based on the results of pilot tests. Generally, revisions were fairly minor, mainly clarifications and shortening.
Future Activities:
Future activities include recruiting and consenting subjects, administering initial and follow-up surveys, implementing the interventions, collecting and analyzing data, and completing papers and reports.
Journal Articles:
No journal articles submitted with this report: View all 10 publications for this projectSupplemental Keywords:
indoor air, exposure, health effects, human health, sensitive populations, VOC, survey, social science, epidemiology, monitoring, Midwest., Health, Scientific Discipline, Air, Epidemiology, Risk Assessments, indoor air, Atmospheric Sciences, Environmental Engineering, building related illness, fresh air exchange, hvac, office buildings, surveys, occupant health, filtration, ventilation rates, ambient air, workplace, human exposure, mitigation strategies, sick building syndrome, furnaces, indoor air quality, air qualityProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.