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4 90-92.6 to slab by the tenants of this space, resulting in severely reduced return air flow. Originally the return air shaft travelled uninterrupted from the basement to the penthouse, providing return air for both units. Apparently there were air balance problems so a divider was built at the 13th floor level of the shaft to completely separate the air from each unit. System Condition. Both main air handling units were found to be operating on 100% return air with the outside air dampers completely closed on the days of our inspection (maximum outside air temperature was 76°F). Both sets of filters were in excellent condition and well fitted in their frames. The filter chambers themselves were clean. There was some slime accumulation and standing water associated with the condensate trays, and some light fungal spots were found on flex ducting and insulation inside some of the chambers. The VAV boxes examined in this inspection all appeared to be in generally clean condition. Several of them had their dampers totally closed at the time of our inspection. The reheaters were equipped with low grade panel filters. Some of the loose spray-on insulation had passed through these filters since some light residues were caught up on the heater coils. In general, however, these units were found to be clean. Visual inspections of the air supply duct internals showed them to be deposited with only trace or light amounts of brown granular materials. Airborne sampling results for this building are shown on Table III. These show low levels of carbon dioxide, carbon monoxide and nicotine, but higherlevels of RSP, formaldehyde and in some areas airborne microbes. In summary, this building reflected its relatively young age and location. The building with a sealed "mirror" finish is typical of most contemporary office structures. It was designed and built at the height of the energy crisis and as a result, ventilation rates in the occupied spaces are at a practical minimum both due to the relatively restrictive design of the air supply system, and by its apparently routine operation with little or no outside air. One might expect to see these low ventilation rates result in high levels of carbon dioxide, but as seen in Table III, this is not the case. This is because of relatively light occupant density, with less than half the number of occupants than were found in Building A. Should the building ever be occupied to occupant densities more common in government buildings, we would expect these carbon dioxide levels to rise substantially, especially in workday afternoons. A further contrast is found in the filtration system, which was generally in an excellent, well maintained condition. This, together with the fact that the building is relatively young, had lead to systems which remain in a generally satisfactory clean condition. As a result, dust levels were found to be generally satisfactory, with only a few areas showing RSP levels over 75 µg/m3. Several types of potentially allergenic fungi were isolated from the mechanical rooms where visible growth was observed, but overall airborne levels in the occupied areas were not excessive. We did note the presence of formaldehyde, which while not at levels which breached the ASHRAE limit, did 11 TI DN 0004458 ©

I 90-92.6 approach it in some areas. In general, other indoor pollutants in this building, including tobacco smoke, were only found at low levels, but there can be no doubt that this building was found to be poorly ventilated, especially in the areas where complaints originated. As an incidental point, this study complements other work16 in that airborne measurements alone might fail to reveal the obvious causes of air quality problems in a building such as this. While individual pollutant levels remain under acceptable standards, a knowledgeable and thorough inspection of the mechanical systems helps to reveal not only the origin of current complaints, but potential for future ones. Recommendations for improvements in this building included opening of the outside air dampers to allow in the minimum outside air ventilation rate of 20 cfm per person, as recommended in ASHRAE Standard 62-89. Also, that the loading dock be equipped with signs instructing drivers to switch their engines off; cleaning and sanitizing of the condensate trays and other areas inside the main AHUs showing visible fungal growth; opening of the ceiling void in areas where slab-to-slab partitioning had been erected; and review of the VAV damper setting policy to ensure adequate fresh air delivery into the occupied spaces. DISCUSSION A simplistic overview of these contrasting buildings indicates that the older government building on the east coast suffered from very poor filtration and relatively high levels of dirt, while the newer commercial office building suffered mainly from ventilation related problems. The contrasting engineering characteristics, however, gave rise to very similar complaints from the building occupants. In our view, this demonstrates that at least at the initial stages of an investigation, little information can be gained from occupant questionnaires which will be ultimately useful in solving indoor air quality problems. Major flaws in air quality related operation and maintenance practices need to be corrected first before indulging in questionnaires, or indeed, any other disruptive practices such as occupant shuffling, carpet removal, or smoking bans. Further problems with occupant questionnaires are likely to be resistance to such an exercise by building management or occupant employers, and the real possibility that questions on health symptoms generate occupant anxiety and eventually lead to a "snowballing" political issue, uncontained by the original and possibly quite genuine complaints. Premature removal of suspect carpets or smoking bans before checking the engineering evaluation would usually only provide temporary relief and other pollutant accumulations would probably manifest themselves at a later date. Filtration. One of the biggest contrasts noted in these two buildings were the filtration systems, one of which was rated as very poor, and the other as excellent. Because choice and maintenance of filtration systems plays an important part in indoor air quality, standards for rating them are crucial to a successful engineering appraisal of an HVAC system. The current ASHRAE Standard 52-76 requests that filter manufacturers specify both a weight test and a dust spot test for each class of filter. 12 TI DN 0004459

90-92.6 i The arrescance test involves a standardized synthetic dust consisting of various particle sizes which is fed into the filter and the weight fraction of the dust removed is determined. The synthetic dusts used are considerably coarser than typical atmospheric dusts in general and indoor air particulate in particular. Since most of the weight of dusts is in the larger particles, the arrestance values are usually high, but these values give no indication of the filter's capability to remove the smaller particles. In general, arrestance values are virtually useless in choosing the suitability of filters for indoor air. The alternative is the atmospheric dust spot test, where atmospheric test dust is passed into the filter and the discoloration effect of the cleaned air is compared with the incoming air. This test does include many of the smaller particles since, although they are small and light, these particles do still soil walls, etc. A disadvantage of this test exists due to the variability of atmospheric dusts, which may cause the same filter to yield different efficiencies at different times or locations. Even this atmospheric dust spot test is unreliable at the smaller particle size range, i.e., below 1.0 microns in diameter. All the ASHRAE Atmospheric Dust Spot Test results give efficiency ratings that are representative of particles greater than 1.0 micron. However, when the suitability of filters from a point of view of human health is considered the sub-micron size particles are of most concern since these are the ones that penetrate deep into the respiratory system and into the lungs. In general, the sum of all the particles of less than 3.5 microns in diameter is described as the Respirable Suspended Particulate (RSP), although most of these particles are less than 1 micron in diameter. In order to make assessments and encourage improvements of filtration systems from the standpoint of an indoor air quality practitioner, some means of comparing filters according to a nationally recognized test procedure that addresses respirable particles is needed. One possible solution to this requirement would be the development of a "standard indoor dust." HVAC filters could then be assessed by their ability to remove this dust from an airstream within their rated airflow capacity. Possibly, with the appropriate standard testing equipment, this dust could be used to test an entire filtration assembly in situ. CONCLUSIONS This study consisted of comprehensive evaluations of two identically sized, yet contrasting office buildings. Despite similar complaints of primarily upper respiratory problems in both buildings, air quality problems were traced to entirely different origins. This calls into question the usefulness of occupant questionnaires in such cases. The two buildings demonstrate markedly different filtration characteristics in particular, which highlights a need for a standard method of evaluation of in situ building filtration systems. A standard indoor air test dust is proposed as a start in developing such a method. 13 TI DN 0004460

9o-92.6 REFERENCES 1. A. Hedge, T.D. Sterling, E.M. Sterling, C.W. Collett, D.A. Sterling and V. Nie, "Indoor Air Quality and Health in Two Office Buildings with Different ventilation Systems," Environmental International 15 (1-6):115 (1989). 2. J.F. Brundage, R. McN. Scott, W.M. Lednar, D.W. Smith, R.N. Miller, "Building-Associated Risk of Febrile Acute Respiratory Disease in Army Trainees," JtA 259(14):2108 (1988). 3. H. Levin, "Sick Building Syndrome: Review and Exploration of Causation Hypothesis and Control Methods," in The Human Eauation: Health and Comfort, IAQ 89, ASHRAE, San Diego 1989, pp. 263-274. J.G. Robertson, "Indoor Pollution: Sources, Effects and Mitigation Strategies," in Proceedines of the 1989 International Symposium on Environmental Tobacco Smoke at McGill Universitv, Lexington Books, Montreal, 1989, pp. 333- 355. 5. C. Molina, C.A.C. Pickering, 0. Valb,jorn, M. DeBortoli, Sick Building_SYndrome. A Practical Guide, Report #4 Cost Project 613, Indoor Air Quality and Its Impact on Man, European Concerted Action, Commission of the European Communitiies, Luxembourg, 1989. 6. EPA, Determination of Nicotine in Indoor Air, Compendium of Methods for the Determination of Air Pollutants in Indoor Air. Method 1P-2A. U.S. Environmental Protection Agency, AREAL, Research Triangle Park, 1989. 7. Bourdillon et al, "Airborne Bacteria Found in Factories and Other Places," MRC Report #263, HMSO, London, pp. 257-263 (1948). 8. T. Wright, V.W. Green, H.J. Paulus, "Viable Microorganisms in an Urban Atmosphere," JAPCA 19, p. 337 (1969). 9. P. Morey, et al, "Environmental Studies in Moldy Office Buildings," Annals ACGIH, 10, pp. 21-35 (1984). 10. M.A. Dourin, "A Study of Atmospheric Mold Spores," Ann. Allerev, 24, pp. 31-36 (1966). 11. G.T. Col, R.A. Sampson, "Mold Allergy," Ed. Y. AL-Doory and J.F. Domson (1984). 12. EPA, National Primary and Secondary Ambient Air Oualitv Standards, Code of Federal Regulations, Title 40 Part 50 (40 CFR 50), 1989. 14 TI DN 0004461

90-92.6 13. American Society of Heating, Refrigerating and Air Conditioning Engineers, Ventilation for Accentable Indoor Air va it , ASHRAE Standard 62-1989, Atlanta (1989). 14. American Conference of Governmental Industrial Hygienists Threshold Limit Values and Biologjcal Exvosure Indices, Cincinnati (1988-89). 15. American Society of Heating, Refrigerating and Air Conditioning Engineers, Method of Testing Air-Cleanine Devices used in General Ventilation for Removine Particulate Matter, ASHRAE Standard 52-76, Atlanta (1976). 16. V.L. Putnam, J.E. Woods, T.A. Bosman, "Objective Measures and Perceived Responses of Air Quality in Two Hospitals," ir.-The Human Eauation: Health and Comfort, IAQ 89, ASHRAE, San Diego 1989, pp. 241-250. NOTE TO EDITORS Under the new federal copyright law, publication rights to this paper are retained by the author(s). 15 TI DN 0004462