M. A. CECIL & ASSOCIATES, INC. 4475 Shannon Way, Port Republic, Maryland 20676 (301) 855-7710 INDUSTRIAL HYGIENE AND ENVIRONMENTAL HEALTH October 17, 2013 Mr. Sean Yarup Montgomery County Public Schools 16651 Crabbs Branch Way Rockville, Maryland 20855 Re: Indoor Air Quality Dear Mr. Yarup: On, M. A. Cecil and Associates Inc., conducted the second of two indoor air quality surveys at. The scope of the work included bioaerosol, mold spores, carbon dioxide, and carbon monoxide, volatile organic compounds, and nuisance particulate sampling and temperature and relative humidity determinations. EVALUATION METHODS BIOAEROSOLS Bioaerosol sampling was performed using a SAS Microbial Air Sampler. The sampler draws air through a microsieve plate at a calibrated rate of air of 180 liters per minute. This process accelerates airborne particles, impacting them onto tryptic soy agar and malt extract agar filled plates. The samples were incubated at 25 C and examined everyday for 7-10 days. Once on the agar plates, viable particles can grow into visible colonies. Their numbers give an indication of the airborne concentration of viable fungi and bacteria. During the incubation period subsequent colonies are isolated, identified (genus) and counted to calculate airborne concentrations for each sample location. SPORE SAMPLING Spore sampling was performed by drawing air through an Aerotrap Spore Sampler and aimed directly at a sticky and optically clear sampling media (microscope slide). An air-sampling rate of ten liters per minute was used. This process accelerates airborne particles, impacting them onto the gel strip inside the sampler. The slides were analyzed via microscopy and particles identified. CARBON DIOXIDE Carbon dioxide (CO 2 ) levels were measured using Grey Wolf Technologies direct reading indoor air quality instrument. The instrument was two-point calibrated prior to use with a certified zero
gas and 1,000 ppm CO 2 span gas. Carbon dioxide was analyzed continuously for ten minutes at each site with average concentrations computed. TEMPERATURE AND RELATIVE HUMIDITY Temperature and relative humidity levels were measured throughout the building using the Grey Wolf Technologies direct reading indoor air quality instrument. Temperature and relative humidity were analyzed continuously for ten minutes with averages computed. CARBON MONOXIDE Carbon monoxide (CO) levels were measured throughout the building using the Grey Wolf Technologies direct reading indoor air quality instrument. The instrument was two-point calibrated prior to use with a certified zero gas and 50 ppm CO span gas. Carbon monoxide was analyzed continuously with average concentrations computed. VOLATILE ORGANIC COMPOUNDS Volatile organic compound samples were collected by drawing room air via a pre-calibrated RAE Systems photo ionization detector (PID). The PID draws in ambient air and analyzes for low concentrations of VOCs. The sampling was conducted simultaneously with carbon dioxide determinations. NUISANCE PARTICULATE Nuisance particulate (dust) sampling was performed with a pre-calibrated TSI Dust Trak Aerosol Monitor. This monitor uses light scattering technology to determine mass concentrations in real time. The instrument was operated for an approximate ten-minute period, with measurements recorded every minute with the on-board data logger. Ten-minute average concentrations were computed. RESULTS AND DISCUSSION BIOAEROSOLS Bioaerosols are airborne particles that are living or that are released from living organisms. These living particles include fungi and bacteria and some of these organisms have been implicated in human respiratory and skin allergies, hypersensitivity reactions and toxic effects. Fungal spores and other viable particles may enter a space through the outside air intakes and due to their small size, are not typically eliminated from the air stream by the building air filtration system. Once they have settled out of the air stream, the spores may grow almost anywhere within a building where conditions permit. Optimal conditions include a surface for growth, organic nutrients, darkness, and moisture. Areas in which microorganisms may proliferate or bioamplify include internal surfaces of air handling units and ducts; especially if insulated, ceiling tiles (wet or moist), carpet, and areas, which remain dark, seldom cleaned, or congested with furniture and office materials. Indoor environmental bacterial populations can be from humans as well as environmental sources. All humans shed skin flakes and bacteria. Commonly detected bacteria in indoor environments such as Micrococcus and Staphylococcus are likely from human sources. Environmental bacteria such as Bacillus and Pseudomonas normally originate from soils, plants, or water. Generally, there 2
is insufficient evidence to show that bacteria are a cause of allergies. Exposure to significant concentrations of airborne bacteria could challenge an individual's immune system. However, bacterial byproducts (proteins and endotoxins) have been suggested as causative agents for occupant illnesses. Fungi (molds and yeasts) produce spores during their growth or reproductive cycle. The asexual and/or sexual spores are often considered allergens. It is not known what concentration of spores is required to evoke an allergic reaction. It is known; that individuals exposed intermittently to significantly elevated levels of allergens or moderate levels continuously for a time period (months or years) may become sensitized. An individual sensitized to an allergenic agent is said to have developed an allergy to that agent. Once sensitized, the individual experiences an allergic reaction at each time of exposure. The degree and extent of the reaction is dependent on the exposure concentration, the length of exposure and the individual. Therefore, a sensitized individual may react to relatively low and in some cases undetectable concentrations of allergens while a nonsensitized or less sensitized individual in the same indoor environment will not experience any symptoms. Airborne fungi and bacteria naturally occur in most indoor environments. Currently, there are no indoor air quality guidelines or regulations for the determination of measured bioaerosol concentrations. However, excessive numbers or unusual types of microorganisms may cause health problems in sensitive individuals. Interpretation of such sample results depends on professional judgment as to whether types and amounts of organisms are comparable to normal background and the likelihood that the identified organisms will cause allergic reactions or infections. Since spores are only released into the air intermittently, any visible growth, water damage, or excessive dust may be considered an indication of potential bioaerosol problems, even where air-sampling results are negative. Bioaerosol samples were collected from classrooms and offices as well as outdoors for comparison. Bioaerosol results are interpreted by comparing indoor concentrations to outdoor concentrations. The total indoor concentrations should be lower than the total outdoor concentration. In addition, the types of mold found indoors should be similar and their concentrations not significantly higher than those found outdoors. The detected fungal concentrations were insignificant and generally below the outdoor concentration. The detected bacterial concentrations were insignificant and generally below the outdoor concentration. The sample locations and detected concentrations, expressed as colony forming units per cubic meter (cfu/m 3 ) of air, are summarized in the attached Table 1. SPORES Spore samples were collected from classrooms as well as outdoors for comparison. Mold spore sample results are interpreted by comparing indoor mold spore concentrations to outdoor mold spore concentrations. The total indoor mold spore concentration should be lower than the total outdoor mold spore concentration. In addition, the types of spores found indoors should be similar and their concentrations not significantly higher than those found outdoors. At the time of the sampling, the detected indoor spore concentrations (total) were less than the outdoor concentration (total). However, the concentration of Penicillium/Aspergillus spores was elevated as compared to the outdoors. Penicillium and Aspergillus mold are common in the environment. In the indoor environment Penicillium/Aspergillus is often found on damp building material drywall, wood and, 3
HVAC equipment surfaces. The types of spores detected indoors were essentially identical to the spores detected outdoors indicating the indoor spores originated outdoors. The sample locations and detected concentrations, expressed as spores per cubic meter (spores/m 3 ) of air, are summarized in the attached Table 2. CARBON DIOXIDE The carbon dioxide data was used to determine the effectiveness of the ventilation system in supplying outside air to the indoor environment. NIOSH indicates that in order to prevent employee discomfort, average carbon dioxide concentrations should not exceed 1000 ppm. ASHRAE recommends not exceeding 700 ppm above the outdoor concentration. The average CO 2 concentration at each sampling location was acceptable. The detected concentrations are summarized in the attached Table 3. TEMPERATURE AND RELATIVE HUMIDITY The primary functions of a building's ventilation system are to control temperature and humidity and to provide clean outdoor air for the dilution of odors and air contaminants. Many complaints of poor air quality are actually caused or exacerbated by temperature and/or humidity values outside the normal comfort ranges recommended by ASHRAE. These ranges are 73-79 F and 40-60% humidity for summer or 68-74 F and 30-50% humidity for winter. The average temperatures and relative humidity were within the ASHRAE recommended comfort range. CARBON MONOXIDE Carbon monoxide (CO) is one of the most prevalent of all indoor air pollutants, introduced into a building from outdoor automobile exhaust, industrial combustion sources, or combustion units for space heating. Indoor sources for air contamination can be produced from tobacco smoke, improperly vented combustion sources, or from leaking heat exchangers. OSHA has established a PEL of 50 parts of CO per million parts of air for an 8-hour industrial exposure. At this level of exposure, it is felt that most people will not experience any adverse health effects. The ambient air quality standard for CO, set by the U.S. Environmental Protection Agency (EPA), is 9 ppm and is considered more appropriate for application to office environments. The average concentrations were less than the instrument detection limit (1.0 ppm). VOLATILE ORGANIC COMPOUNDS Volatile organic compounds will off gas from numerous items associated with the indoor environment, especially new items. Odor and irritation responses to organic compounds are highly variable. The complaints and symptoms associated with exposure to VOCs may include: mental fatigue, headache, irritation of eye, nose and throat, and nonspecific airway hyperactivity reactions. The detected concentrations were below the maximum concentration (500 ppb) established by the U.S. Green Building Council s, LEED Indoor Environmental Quality program. 4
NUISANCE PARTICULATE Elevated levels of nuisance particulate or dust may cause employee health responses including cough, scratchy throat, and upper respiratory irritation. Detected concentrations were insignificant and ranged between 0.015 and 0.036 milligrams per cubic meter (mg/m 3 ) of air. The detected concentrations were below the maximum concentration (0.05 mg/m 3 ) established by the U.S. Green Building Council s, LEED Indoor Environmental Quality program. The detected concentrations are listed in the attached table. CONCLUSION/RECOMMENDATIONS The results for the commonly evaluated indicators of indoor air quality were within acceptable ranges with the exception of the spore levels in classrooms B102 and B211. Given the variability in mold spore sampling it is difficult to determine if the sampling results indicate indoor mold activity. There were no signs of water damage or apparent mold growth in the classroom. However, suspect sources for the elevated levels include the room s fan coil unit which may not have been cleaned sufficiently, the rooftop energy recovery unit (ERU) which was cleaned after this survey, and the relatively large number of potted plants in the room. Water damaged ceiling tiles were noted in Room C103 (above exterior door), Room B110 (at entrance), and in Room C205. Dehumidifiers were noted in B110, B108, Room B205, and C200. A thorough inspection of classrooms B102 and B211 and the fan coil units should be conducted. Particular attention should be given to likely areas for water intrusion into the rooms. Fan coil unit inspections should include internal unit insulation, condensate pans, and other surfaces in contact with supply air flow. If no evidence of mold is identified then a thorough cleaning of the classrooms and units should be conducted. Porous surfaces should be vacuumed with a HEPA filtered vacuum. Non porous surfaces should be wet wiped with a household cleaner/water solution. In addition, remove water damaged ceiling tiles and other materials, inspect and repair or prevent routes of water intrusion and replace water damaged materials as necessary. Conduct routine vacuuming and dusting with a high efficiency or HEPA filtered vacuum. Should you have any questions concerning this matter please do not hesitate to contact this office at (703) 721-0400 or (301) 855-7710. Sincerely, Kim Fowler Industrial Hygienist Michael A. Cecil, CIH 5
Table 1 Bioaerosol Sampling Results Room/Location Presumptive Bacterial & Fungal ID Raw Count Concentration(cfu/m 3 ) Bacillus species 15 106 Micrococcus species 13 92 Total Bactria 28 198 C103 Aspergillus niger 2 14 Cladosporium species 26 183 Nigrospora species 2 14 Penicillium species 5 35 Total Fungal 35 246 Bacillus species 29 204 Micrococcus species 18 127 Streptomyces species 1 7 Total Bactria 48 338 C100 Aspergillus niger 2 14 Cladosporium species 20 141 Non-sporulating colony 2 14 Penicillium species 1 7 Total Fungal 25 176 Bacillus species 10 70 Coag-negative Staphylococcus species 2 14 Micrococcus species 10 70 B110 Total Bacteria 22 154 Cladosporium species 8 56 Penicillium species 3 21 Yeast 1 7 Total Fungal 12 84 Bacillus species 6 42 Micrococcus species 2 14 Streptomyces species 1 7 B111 Total Bactria 10 70 Cladosporium species 19 134 Fusarium species 1 7 Non-sporulating colony 1 7 Penicillium species 3 21 Total Fungal 24 169 Micrococcus species 7 49 Total Bacteria 8 56 B109 Acremonium species 1 7 Cladosporium species 11 77 Non-sporulating colony 1 7 Pithomyces species 2 14 Total Fungal 15 105 6
Table 1 (continued) Bioaerosol Sampling Results Room/Location Presumptive Bacterial & Fungal ID Raw Count Concentration(cfu/m 3 ) Bacillus species 4 53 Micrococcus species 5 67 Total Bactria 9 120 B106 Aspergillus species 1 13 Cladosporium species 10 133 Non-sporulating colony 1 13 Paecilomyces species 1 13 Total Fungal 13 172 Bacillus species 1 13 Micrococcus species 5 67 Total Bactria 6 80 Cladosporium species 7 93 B107 Epicoccum species 1 13 Non-sporulating colony 1 13 Penicillium species 1 13 Pithomyces species 11 147 Total Fungal 21 279 Bacillus species 4 53 Coag-negative Staphylococcus species 2 27 Micrococcus species 4 53 Total Bacteria 10 133 B102 Aspergillus species 1 13 Cladosporium species 14 187 Epicoccum species 1 13 Penicillium species 2 27 Pithomyces species 5 67 Total Fungal 23 307 Bacillus species 5 35 Micrococcus species 15 106 Non-fermentative gram negative rod 1 7 Total Bacteria 21 148 B101 Alternaria species 1 7 Cladosporium species 6 42 Epicoccum species 1 7 Penicillium species 6 42 Pithomyces species 1 7 Total Fungal 15 105 Bacillus species 7 49 Micrococcus species 6 42 A102 Total Bacteria 14 98 Chaetomium species 1 7 Cladosporium species 5 35 Pithomyces species 1 7 Total Fungal 7 49 7
Table 1 (continued) Bioaerosol Sampling Results Room/Location Presumptive Bacterial & Fungal ID Raw Count Concentration(cfu/m 3 ) Bacillus species 2 14 A101 Micrococcus species 4 28 Total Bacteria 7 49 Cladosporium species 5 35 Total Fungal 5 35 Bacillus species 14 99 Micrococcus species 5 35 Total Bacteria 19 134 Media Center Acremonium species 2 14 Chaetomium species 1 7 Cladosporium species 4 28 Total Fungal 7 49 Bacillus species 8 56 Micrococcus species 2 14 B204 Total Bacteria 11 77 Cladosporium species 4 28 Non-sporulating colony 1 7 Total Fungal 5 35 Bacillus species 9 63 Micrococcus species 7 49 Total Bacteria 16 112 B200 Arthrospore-former 1 7 Cladosporium species 7 49 Non-sporulating colony 1 7 Total Fungal 9 63 Bacillus species 3 21 Micrococcus species 2 14 A203 Total Bacteria 6 42 Cladosporium species 5 35 Curvularia species 1 7 Total Fungal 6 42 Bacillus species 6 42 Micrococcus species 4 28 Total Bacteria 10 70 Chaetomium species 1 7 A200 Cladosporium species 8 56 Non-sporulating colony 1 7 Penicillium species 1 7 Pithomyces species 4 28 Total Fungal 15 105 8
Table 1 (continued) Bioaerosol Sampling Results Room/Location Presumptive Bacterial & Fungal ID Raw Count Concentration(cfu/m 3 ) Bacillus species 3 21 Micrococcus species 9 63 Total Bacteria 12 84 A202 Cladosporium species 35 246 Penicillium species 8 56 Pithomyces species 4 28 Total Fungal 47 330 Bacillus species 5 35 Micrococcus species 13 92 Total Bacteria 18 127 A201 Alternaria species 1 7 Cladosporium species 7 49 Fusarium species 1 7 Pithomyces species 1 7 Total Fungal 10 70 Bacillus species 11 77 Micrococcus species 8 56 Total Bacteria 19 133 B210 Aspergillus fumigatus 1 7 Aspergillus niger 1 7 Cladosporium species 16 113 Non-sporulating colony 1 7 Total Fungal 19 134 Bacillus species 58 408 Total Bacteria 58 408 Alternaria species 2 27 Aspergillus niger 12 160 B211 Cladosporium species 27 360 Penicillium species 2 27 Pithomyces species 1 13 Syncephalastrum species 1 13 Total Fungal 45 600 Bacillus species 5 35 Micrococcus species 1 7 Total Bacteria 6 42 Aspergillus fumigatus 1 7 B214 Cladosporium species 15 106 Paecilomyces species 1 7 Penicillium species 3 21 Pithomyces species 1 7 Total Fungal 21 148 9
Table 1 (continued) Bioaerosol Sampling Results Room/Location Presumptive Bacterial & Fungal ID Raw Count Concentration(cfu/m 3 ) Bacillus species 22 155 Micrococcus species 12 85 Total Bacteria 34 240 Alternaria species 1 7 C202 Cladosporium species 2 14 Coelomycete species 1 7 Penicillium species 1 7 Pithomyces species 1 7 Total Fungal 6 42 Bacillus species 8 56 Micrococcus species 7 49 Streptomyces species 1 7 C203 Total Bactria 17 119 Acremonium species 2 14 Alternaria species 1 7 Cladosporium species 5 35 Total Fungal 8 56 Bacillus species 24 169 Micrococcus species 7 49 Total Bactria 32 225 APR Alternaria species 1 7 Cladosporium species 6 42 Coelomycete species 1 7 Epicoccum species 1 7 Pithomyces species 1 7 Total Fungal 10 70 Bacillus species 7 49 Total Bactria 7 49 Alternaria species 3 21 Outdoors Cladosporium species 50 352 Epicoccum species 1 7 Penicillium species 4 28 Pithomyces species 3 21 Total Fungal 61 429 10
Table 2 Spore Sampling Results September 30, 2013 Location Presumptive Fungal ID Raw Count Concentration(spore/m 3 ) Basidiospores 2 Cladosporium 37 C103 Drechslera/Bipolaris group 1 Penicillium/Aspergillus group 7 Pithomyces 6 Smuts, Periconia, Myxomycetes 2 Total: 759 Ascospores 2 Basidiospores 13 Cladosporium 17 C100 Epicoccum 3 Hyphal elements 5 Penicillium/Aspergillus group 14 Smuts, Periconia, Myxomycetes 3 Unknown 1 Total: 787 Basidiospores 19 Cladosporium 6 B110 Hyphal elements 2 Penicillium/Aspergillus group 3 Pithomyces 1 Rusts 1 Smuts, Periconia, Myxomycetes 1 Total: 452 Basidiospores 15 Cladosporium 8 B111 Drechslera/Bipolaris group 1 Epicoccum 1 Hyphal elements 1 Penicillium/Aspergillus group 7 Smuts, Periconia, Myxomycetes 3 Total: 492 Basidiospores 18 B109 Cladosporium 11 Penicillium/Aspergillus group 1 Smuts, Periconia, Myxomycetes 1 Total: 426 Basidiospores 15 B106 Cladosporium 8 Hyphal elements 2 Penicillium/Aspergillus group 3 Total: 387 11
Table 2 (continued) Spore Sampling Results Location Presumptive Fungal ID Raw Count Concentration(spore/m 3 ) Basidiospores 8 Cladosporium 2 B107 Penicillium/Aspergillus group 1 Pithomyces 2 Smuts, Periconia, Myxomycetes 1 Total: 187 Ascospores 2 Basidiospores 6 Cladosporium 13 B102 Hyphal elements 4 Penicillium/Aspergillus group 32* Smuts, Periconia, Myxomycetes 2 Total: 7,200 Ascospores 2 Basidiospores 36 Cladosporium 8 B101 Hyphal elements 1 Penicillium/Aspergillus group 6 Pithomyces 1 Smuts, Periconia, Myxomycetes 1 Stachybotrys 1 Total: 746 Basidiospores 19 Cladosporium 2 A102 Penicillium/Aspergillus group 44 Pithomyces 1 Smuts, Periconia, Myxomycetes 1 Total: 919 Basidiospores 17 A101 Cladosporium 5 Penicillium/Aspergillus group 5 Pithomyces 1 Total: 400 Basidiospores 20 Cladosporium 10 Media Center Curvularia 2 Hyphal elements 1 Penicillium/Aspergillus group 1 Total: 453 Basidiospores 68 Cladosporium 15 B204 Curvularia 2 Penicillium/Aspergillus group 5 Pithomyces 1 Smuts, Periconia, Myxomycetes 2 Total: 1,241 12
Table 2 (continued) Spore Sampling Results Location Presumptive Fungal ID Raw Count Concentration(spore/m 3 ) Basidiospores 16 B200 Cladosporium 10 Penicillium/Aspergillus group 2 Total: 399 Ascospores 2 Basidiospores 51 A203 Cladosporium 15 Penicillium/Aspergillus group 4 Total: 973 Basidiospores 33 Cladosporium 10 A200 Epicoccum 1 Penicillium/Aspergillus group 8 Pithomyces 2 Total: 720 Basidiospores 15 A202 Cladosporium 13 Penicillium/Aspergillus group 2 Pithomyces 1 Total: 1.826 Alternaria 1 A201 Basidiospores 32 Cladosporium 5 Penicillium/Aspergillus group 3 Total: 560 Ascospores 5 Basidiospores 53 B210 Cladosporium 35 Hyphal elements 5 Penicillium/Aspergillus group 47 Total: 1,935 Alternaria 3 Ascospores 3 Basidiospores 20 Cladosporium 12 Curvularia 8 B211 Drechslera/Bipolaris group 3 Hyphal elements 28 Penicillium/Aspergillus group 33* Pithomyces 2 Rust 1 Smuts, Periconia, Myxomycetes 6 Total: 4,667 13
Table 2 (continued) Spore Sampling Results Location Presumptive Fungal ID Raw Count Concentration(spore/m 3 ) Basidiospores 82 Cladosporium 10 Epicoccum 1 B214 Hyphal elements 3 Penicillium/Aspergillus group 22 Pithomyces 1 Rust 1 Smuts, Periconia, Myxomycetes 1 Total: 1,611 Alternaria 1 Ascospores 3 Basidiospores 36 C202 Cladosporium 15 Hyphal elements 2 Penicillium/Aspergillus group 4 Smuts, Periconia, Myxomycetes 2 Total: 840 Basidiospores 52 C203 Cladosporium 4 Penicillium/Aspergillus group 1 Total: 772 Alternaria 1 Basidiospores 18 Cladosporium 6 APR Curvularia 2 Hyphal elements 3 Penicillium/Aspergillus group 3 Polythrincium 1 Smuts, Periconia, Myxomycetes 2 Total: 2,160 Alternaria 2 1 Basidiospores 78 Cercospora 3 Cladosporium 18 Drechslera/Bipolaris group 1 Outdoors Epicoccum 1 Hyphal elements 4 Penicillium/Aspergillus group 7 Pithomyces 1 Polythrincium 1 Pyricularia 1 Rusts 1 Smuts, Periconia, Myxomycetes 11 Total: 11,864 14
Location Carbon Dioxide (ppm) Table 3 Indoor Air Quality Parameters Rolling Terrace Elementary Average Temp. (ºF) Relative Humidity (%) Carbon Monoxide (ppm) Volatile Organic Compounds (ppb) Nuisance Dust (mg/m 3 ) Outdoors 367 67.0 64.0 <1.0 5 0.018 Classroom C103 578 72.3 56.1 <1.0 12 0.015 Classroom C100 490 73.9 54.0 <1.0 27 0.016 Classroom B110 648 74.8 49.3 <1.0 82 0.015 Classroom B111 453 75.8 49.7 <1.0 28 0.018 Classroom B109 467 75.4 49.2 <1.0 72 0.013 Classroom B106 479 75.9 49.8 <1.0 112 0.016 Classroom B107 503 75.0 50.2 <1.0 63 0.018 Classroom B102 628 75.7 51.5 <1.0 27 0.016 Classroom B101 485 75.0 50.0 <1.0 112 0.015 Classroom A102 576 74.7 52.7 <1.0 88 0.017 Classroom A101 474 75.3 49.6 <1.0 115 0.020 Media Center 472 71.4 50.5 <1.0 99 0.017 Classroom B204 460 74.8 48.8 <1.0 35 0.021 Classroom B200 470 75.5 48.4 <1.0 72 0.016 Classroom A203 476 76.1 47.5 <1.0 110 0.017 Classroom A200 482 75.6 47.4 <1.0 38 0.017 Classroom A202 426 76.0 47.2 <1.0 93 0.019 Classroom A201 455 75.8 47.6 <1.0 88 0.017 Classroom B210 436 75.0 48.1 <1.0 120 0.030 Classroom B211 478 75.8 49.6 <1.0 118 0.036 Classroom B214 462 76.7 46.6 <1.0 53 0.021 Classroom C202 567 77.1 47.6 <1.0 66 0.021 Classroom C203 477 76.8 46.5 <1.0 82 0.019 APR 532 74.2 49.7 <1.0 66 0.017 15