1 8 Indoor Air Quality Update September 1992 The building had a constant-air-volume venUla­ air intake to 10 cfmpp. The lowest they could tion system with an economizer. A single air in­ achieve was 20.4 cfmpp. Neither did they reach take was on the 11th floor. During the study, 50 cfmpp, achieving only 33 cfmpp one week 0 fresh air volume was supposed to vary weekly and 47.5 cfmpp the other. on each floor from 10 cubic feet per minute per This led them to recommend that future studies person (cfmpp). the Montreal standard: to 20 using this technique limit the attempt to the cfmpp, the ASHRAE standard: and 50 cfmpp, a two extreme levels, bettering the chance for a standard proposed by the Ontario Department greater variance. of Labour. The building operator and engineer, the only ones who knew the ventilation level Both time and the questionnaire type were im­ each week, overrode the economizer cycle and portant in results reported by the subjects. used the building's heating and cooling systems, Those respondents who used an open-ended rather than outside air, to maintain temperature questionnaire reported fewer symptoms as the and humidity. study went on, ranging between 11 o/o and 36% lower than those respondents with direct probe Measuring the Results questionnaires. Each Wednesday during the six weeks of the Researchers conclude from the temporal study, the researchers measured temperature, phenomenon that future researchers should humidity, and C02 three times at 10 work sites allow for the variation when designing a study. on each floor. They measured outdoor air sup­ The researchers also suggest that the choice of a ply using the C02 measurements and sulfur questionnaire was crucial. Those subjects who hexafluoride (SF6) tracer gas decay. used the open-ended style questionnaire At the beginning of the study, workers in the ex­ reported 22% fewer symptoms in general than periment filled out a baseline questionnaire and those with the direct questionnaire. completed additional queries on each Wednes­ The team also discovered through work site day afternoon in one of two formats: a direct measurements that exposure to building condi­ probe and an open-ended questionnaire. The tions is not homogeneous for all workers. There­ questionnaires tested worker symptoms in re­ fore, they recommend local work site measuring sponse to environmental changes, and whether for a more accurate reading. the respondents had been "unblinded," that is, whether they knew what changes in ventUatlon For more information, contact: Dr. Robyn M. levels they were experiencing. Tamblyn, Lady Meredith House, Clinical Epi­ demiology, 1110 Pine Avenue West, Montreal, Researchers discovered that building leaks PQ H3A 1A3, Canada; (514) 398-3324. frustrated their attempts at restricting outdoor CASE STUDY [Jn each issue IAgU presents a case study on an investigation of indoor air problems in a particular building. The editorial staff relies on information provided. by the environmental consultants involved tn the investigation. lAQU presents a variety of approaches to investigation and mitigation implemented by consultants with a broad range of experience, philosophies, and expertise. Inclusion of a particular case study in the newsletter does not imply IAl!JU's endorsement of the investigative procedures, analysis, or mitigation techniques employed tn the case. IAl!JU.invites readers to submit comments, suggestions, and questions concerning any case. At the discretion of the editors, correspondence may be presented in a.future issue.) Wet-Process Copier Fumes Elevate TVOC Levels in Four Buildings We usually present a case study that examines dividual situation in each structure, as did problems and solutions in a single building. management's response. However, this case involves four buildings, all lo­ All four buildings are located in the province of cated in Canada. where the IAQ problems Quebec, where the winter season is cold and stemmed from copying machines. The recom­ windy (low of -20'C, -4'F) and the summer mended solutions differed according to the in- season is hot and damp (high of 30'C, 86'F). © 1992 Cutter Information Corp. September 1992 Indoor Air Quallty Update 9 Table 3-HVAC Investigation Techniques Ventilation Factors Testing Method Sampllng Method Fresh Air Change Rates Tracer gas decay using sulfur Automated system collected samples hexafluoride (SFs) and gas from each floor, or velocity chromatography, or anemometer measurements were made at the total system air duct Air Distribution Balometer Measurements at diffusers by direct- reading balometer Reentrainment of Exhaust Air Injection of SFs into exhaust system Sampling by direct-reading instruments at outdoor intakes of each HVAC system Installation and Operational Problems Visual inspection Visual inspections and walk-through With HVAC Systems Thermal Comfort/Relative Humidity Spot readings of relative humidity, air All the instruments are installed on a velocity, and dry bulb and radiant cart and data are recorded by a temperatures recorded at 2.75 inches, technician pushing the cart through all 29.5 inches, and 73 inches above selected stations floor level None of the buildings had windows that could • Measurements of fresh air change rates using be opened. In each case, building occupants tracer gas decay: had reported problems for a number of years, • Direct-reading balometer measurements of air but no one had investigated previously. Also, distribution: in each case, symptoms affected more than 50016 of the occupants and included: difficulty con­ • Measurement of exhaust reentrainment: centrating, tendency to fall asleep, lack of • Visual HVAC inspections: and energy, dry throat problems, and sneezing and • Spot readings of humidity, air velocity, and coughing. temperatures. The investigative teams, while differing from The IAQ assessment of each building (outlined case to case, generally consisted of several en­ in Table 4) consisted of: gineers and engineering students from the same consulting company. This team followed a • Infrared detection of CO and C02: general IAQ inspection routine, as well as the • Charcoal-type filters connected to air pumps to study of specific contaminants, such as voes. measure total volatile organic compounds lead, and microo_rganisms. ('IVOCs); The HVAC investigation techniques (outlined in • Passive dosimeters installed for three days to Table 3) included: measure formaldehyde: and Table 4- IAQ Assessment Techniques Contaminant Measurement Technique Accuracy Measurement Locations Carbon Monoxide (CO) Infrared detector Range: 0-100 ppm; Selected workstations and Precision: 1% full scale outside air Carbon Dioxide (C02) Infrared detector Range: 0-5,000 ppm; Selected workstations and Precision: 1% full scale outside air Total Volatile Organic Charcoal-type filters Range: 0-100 ppm; Selected workstations and Compounds (TVOCs) connected to air pumps Precision: 2.5 ppb outside air Formaldehyde (HCHO) Passive dosimeters Range: 0-100 ppm; Selected workstations and installed for three Precision: 1% full scale outside air consecutive days Suspended Particulates PVC filter analyzed by Precision: 5 µg/m3 Selected workstations and gravimetry outside air © 1992 Cutter Information Corp. l i 10 Indoor Air Quality Update September 1992 • PVC filters analyzed by gravimetry to indicate (AHIA) recommended limit of 5,000 µg/m3. suspended particles. Most voe contamination came from the wet­ process photocopiers. Case 1 0 Building and HVAC Description Recommendations for Mitigation This tight glass office building and courthouse Investigators recommended increasing humidity of unknown age consists of four stories, plus the in winter and relocating the fresh air intake that basement, and features both closed offices and was responsible for reentraining auto exhaust. open areas with partitions. No recent renova­ They also suggested that the clients duct the tions had been done. Two H-type systems with wet-process copiers. The clients adopted all variable fresh air volume provide HVAC for the recommendations. While no followup has been facility. Approximately 100 people occupy the conducted yet, building owners, management, structure on a permanent basis, and up to 300 and the employee unions have been very satis­ clients visit at a time. fied with the results, and report an alleviation of the symptoms that prompted the investigation. HVAC Investigation Investigators reported that the HVAC system ap­ Case2 peared to be very clean with evidence of a good Building and HVAC Description maintenance program. A tight glass structure, this office building, ap­ proximately 30 years old, consists of four stories Indoor temperature varied from 20.3°C to 25.8°C 2 (69°F to 78°F). and the relative humidity (RH) plus the basement, totalling about 10,266 m . varied from 20% to 59%. Workers in the build­ Two HVAC systems provide 100% fresh air for ing, however, reported that in winter the RH the 500 occupants who worked in both closed stayed around 20%, leading to numerous com­ offices and open areas with partitions. plaints of dryness. The air change rate, ap­ HVAC Investigation proximately 10.2 liters per second per person The HVAC investigation revealed that the fresh (l/s/p). complied with ASHRAE's standard of 10 air change rate varied from 20.5 to 96.41/s/p, l/s/p. The air distribution rate was 240 l/s/p, depending on the floor that was under study. () five times higher than what is required by Even at the minimum, this was well above the Quebec law. 10 l/s/p recommended by ASHRAE. The air dis­ Suspecting reentrainment of automobile ex­ tribution varied from 42 to 421 l/s/p, again haust, the researchers also conducted a fume depending on the floor. Investigators found that test at the parking lot, sampling by direct-read­ crowding on some of the floors meant the occu­ ing instruments at each HVAC intake. These pants of these floors did not receive enough air. indicated that some exhaust fumes were being Tests indicated no problem with reentrainment reentrained. of exhaust air, and the HVAC system seemed to IAQ Assessment be well maintained, although the diffusers were Indoor and outdoor concentrations of CO reg­ a little dirty.