Indoor air quality in a middle school, Part II: Development of emission factors for particulate matter and bioaerosols

A middle school (grades 6 to 8) in a residential section of Springfield, Illinois, with no known air quality problems, was selected for a baseline indoor air quality survey. The study was designed to measure and evaluate air quality at the middle school with the objective of providing a benchmark for comparisons with measurements in schools with potential air quality problems. The focus of this article is on the development of emission factors for particulate matter and bioaerosols. The school was characterized as having no health complaints and good maintenance schedules. Four indoor locations including the cafeteria, a science classroom, an art classroom, the lobby outside the main office, and one outdoor location were sampled for various environmental comfort and pollutant parameters for one week in February 1997. Integrated samples (eight-hour sampling time) for respirable and total particulate matter, and short-term measurements (two-minute samples, three times per day) for bioaerosols were collected on three consecutive days at each of the sampling sites. Continuous measurements of carbon dioxide were logged at all locations for five days. Continuous measurements of respirable particulate matter were also collected in the lobby area. A linear relationship between occupancy and corresponding carbon dioxide and particle concentrations was seen. A completely mixed space, one compartment mass balance model with estimated CO2 generation rates and actual CO2 and particulate matter concentrations was used to model ventilation and pollutant emission rates. Emission factors for occupancy were represented by the slope of emission rate versus occupancy scatter plots. The following particle and bioaerosol emission factors were derived from the indoor measurements: total particles: 1.28 mg/hr/person-hr; respirable particles: 0.154 g/hr/person-hr; total fungi: 167 CFU/hr/person-min; thermophilic fungi: 35.8 CFU/hr/person-min; mesophilic fungi: 119 CFU/hr/person-min; total bacteria: 227 CFU/hr/person-min; gram-negative bacteria: 69.5 CFU/hr/person-min; gram-positive bacteria: 191 CFU/hr/person-min; Aspergillus: 17.0 CFU/hr/person-min; Penicillium: 161 CFU/hr/person-min; and yeasts: 16.4 CFU/hr/person-min.     

Analysis of CO<Subscript>2</Subscript> monitoring data demonstrates poor ventilation rates in Albanian schools during the cold season

Poor ventilation in schools is associated with accumulation of indoor-generated pollutants, which is associated with “stuffy” air, elevated risk of infectious diseases and impaired learning outcomes. This survey in Albania was conducted as part of WHO’s efforts to facilitate assessments of indoor air quality and other environmental factors in schools in the European Region. The survey was conducted in 36 classrooms in 12 middle schools (eight urban and four rural) from December 2011 through March 2012. In each school, carbon dioxide (CO₂) was continuously measured in three classrooms during one school week. Ventilation rates during classes were estimated using the build-up and steady-state mass balance equations utilizing CO₂ concentration data, classroom occupancy and classroom volume. All 12 schools had gravimetric ventilation systems. Heating systems were absent or not operational in most schools. Average classroom temperatures during lessons varied from 9.1 to 14.4 °C (median 11.7 °C) with lower temperature associated with poorer ventilation. Weekly average CO₂ levels during classes ranged from 1286 to 5546 ppm (median 2776 ppm) while average ventilation rates ranged from 0.8 to 3.6 (median 1.8) litres per second per person. Classrooms with indoor combustion heaters had higher indoor temperature, lower CO₂ levels and higher levels of carbon monoxide (CO). WHO guidelines on 1- and 8-h CO exposure levels were exceeded in one classroom. Classroom CO₂ levels were substantially above and ventilation rates below existing national and international guidelines. Detrimental impacts of poor ventilation on health and learning outcomes are likely to be substantial in Albanian schools during the cold season. Indoor temperature in most classrooms was below the commonly recommended levels.     

Indoor air quality assessment of daycare facilities with carbon dioxide,temperature, and humidity as indicators

Poor indoor air quality (IAQ) in daycare facilities affects both attending children and care providers. Incident rates of upper-respiratory-tract infections have been reported to be higher in children who attend daycare. Excessive carbon dioxide (CO2) exposure can cause several health effects and even sudden infant death. For this study, 26 facilities were randomly selected in a Midwestern county of the United States. CO2, room temperature, and relative humidity were used as indicators for IAQ and comfort levels. These IAQ parameters were continuously monitored for eight hours at each facility by a direct-reading instrument that was calibrated before each measurement. More than 50 percent of the facilities had an average CO2 level over the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) standard of 1,000 parts per million (ppm). For temperature and relative humidity, respectively, 42.3 percent and 15.4 percent of facilities were outside of the ASHRAE-recommended comfort zones. The nap-time average CO2 level was about 117 ppm higher than the non-nap-time level. The increment of the nap-time CO2 level in the sleeping-only room over the level in multipurpose rooms was statistically significant (p < .05). According to stepwise multiple regression analysis, nap-time CO2 level was predicted by CO2 level before occupancy, nap-time average temperature, carbon monoxide, and child density (R2 = .83). It is recommended that an appropriate IAQ standard for daycare facilities be established and that children should not be placed in a completely isolated room during nap time.     

青岛市某学校室内空气质量卫生学评价

目的了解学校教室、实验室、阅览室、体育馆、餐厅的室内空气质量,为保护学生身体健康、改善室内环境质量提供依据。方法对青岛市某学校学生日常活动场所的室内温度、湿度、风速、CO、CO2、甲醛、PM10、空气细菌总数共8项指标进行检测和分析。结果该学校室内污染较严重的是甲醛、可吸入颗粒物,场所的超标率分别为80%和50%;污染较轻微的是CO2和空气细菌总数,场所的超标率分别为20%和10%。室内甲醛浓度和CO2浓度、室内PM10浓度与室外PM10浓度、空气细菌总数与室内风速指标间的相关性具有统计学意义(P<0.05)。结论学校应采取定时通风、安装智能室内通风系统、使用符合卫生要求的课桌椅和装修材料以及绿化校园等有针对性的措施改善教室空气质量。     

Modelling indoor air quality: validation and sensitivity

The main objective of this work is to extend the knowledge of indoor air quality by using a numerical tool to calculate the concentrations of pollutants in the indoor air of a classroom. The application of a numerical model allowed to quantitatively assess the impact of several proposed improvement measures, through the simulation of scenarios.The numerical model CONTAM was used to characterise the indoor air quality in a classroom of an elementary school, in terms of concentrations of carbon dioxide, carbon monoxide and particulate matter. The results of the CONTAM simulations were compared to measurements performed during monitoring campaigns (SINPHONIE project). The simulated and measured carbon dioxide and carbon monoxide concentrations inside the classroom are in good agreement. Furthermore, for particulate matter, simulated values show a significant difference from measured values, which are higher overall. With the goal of maximising the indoor air quality of the classroom, several alternative scenarios were simulated. The door and windows of the classroom were opened or closed at different times for each scenario. The scenario promoting the best indoor air quality (i.e. with the lowest concentrations of carbon dioxide and carbon monoxide) is the one in which the door is only open to allow students to get in and out of the room, and the window is kept half-open during the entire day.     

Evaluation and determinants of airborne bacterial concentrations in school classrooms

A survey of 39 elementary schools was undertaken to determine indoor air concentrations of bioaerosols within a coastal, temperate climatic zone in British Columbia, Canada. This article reports the results for airborne bacteria. Determinants of exposure were grouped into environmental (outdoor temperature, relative humidity, season, weather), ventilation and comfort parameter (indoor relative humidity, temperature, indoor CO2 concentration, indoor fungal concentration), and occupancy (number of occupants, activity levels, occupancy patterns) variables. Regression modeling was used to evaluate the association between these factors and measured concentrations of indoor mesophilic bacteria. Naturally ventilated rooms (47% of the total rooms surveyed) had higher bacterial counts than mechanically ventilated rooms (geometric mean 325 vs. 166 CFU/m3, respectively, p < 0.001). In univariate analyses, bacterial counts were negatively correlated with supply and exhaust flow rates, air exchange rates, and the percentage of the day that occupants spent quietly sitting at their desks. Analysis of bacterial groups indicated various sources of the bacterial aerosol, with micrococci and staphylococci closely associated with occupancy variables, Bacillus with site and occupancy, and coryneform bacteria with site variables only. Approximately 60% of the variance in the outcome measurement of total bacteria was accountedfor by indoor CO2, lower air exchange rate, the age of the building, signs of current or old moisture stains, room volume, indoor relative humidity, and occupant activity level in a multiple linear regression model, with ventilation factors accounting for 40% of the variance.     

"Breathing freely" in schools--results and model approaches concerning the air quality in classrooms

Seven schools in Lower Saxony participated in a scientific re-search project measuring the concentration of carbon dioxide (CO2), indoor air temperatures and the relative air humidity in naturally ventilated classrooms on 58 days during the period of one year. The results are as follows: The hygienic reference value of 1500 ppm CO2 (in accordance with the official German regulation DIN 1946-2) was exceeded on 7 days in summer when measurements were taken (32% of all samples in summer) and on 32 days in winter (89% of all samples in winter). The mean CO2-concentration was 1316 ppm, 766 ppm and 1652 ppm in all samples (58 measuring days), summer samples (22 measuring days) and winter samples (36 measuring days), respectively. The mean indoor air temperature was 21.7 degrees C, 22.9 degrees C and 20.9 degrees C. The mean relative humidity was 50.7%, 54.3% and 48.5%. The mean number of persons per classroom (including the teacher) was 25.1, corresponding to a mean volume of 8.5 m3 for each person and a mean area of 2.9 m2 per person. A statistical association of CO2 concentration with season, outdoor temperature and the age of the windows was found. A software programme has been developed for calculating the concentration of CO2 depending on the number of persons and the ventilation rate in a classroom. A 3-level scheme based on CO2 concentration was developed to assess the air quality. The results showed that the classrooms were not ventilated regularly but depending on the outdoor temperature and the season. Deficits concerning all 3 parameters were found. It is very likely that the deficits are not limited to the schools participating in this project. Ventilation and indoor climate deficits might cause health problems and therefore lead to costly measurement programmes. To enable schools to take their own health-related measurements, measuring instruments were purchased which can be loaned to schools in Lower Saxony.     

Exposure assessment of non-electric ice resurfacer operators in indoor ice rinks: a pilot study

Exposure of ice resurfacer operators to indoor air contaminants was measured in six indoor ice arenas. A standardized questionnaire on technical and operational features was employed and indoor airborne concentrations of carbon monoxide (CO), carbon dioxide (CO₂), nitric oxide (NO), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and total volatile organic compounds (VOCs) were measured. Air samples were collected using a range of direct reading instruments attached to the driver’s seat of the resurfacer. The range of mean exposure concentrations via positional sampling (i.e. as close as able to the operator’s breathing zone) were 5.7–7.4 ppm, 694–2171 ppm, <0.5 to 0.5 ppm, and < 0.1 to 0.2 ppm, for CO, CO₂, NO, and NO₂, respectively. Exposure levels for SO₂ and VOC were below detection. Overall, each of the measured indoor air contaminants was found to be below its respective occupational exposure limits (OEL), suggesting that the risk of hazardous exposure is low. The use of natural gas as a fuel source is believed to contribute to low contaminant concentrations.     

上海市黄浦区市级综合医院候诊输液室空气质量调查

[目的]了解上海市黄浦区市级综合性医院候诊输液室的空气质量及影响因素。[方法]对医院候诊及输液区域的室内卫生指标和集中空调通风系统卫生指标进行检测,根据《公共场所卫生监测技术规范》要求设点检测,以《医院候诊室卫生标准》和《公共场所集中空调通风系统卫生规范》进行评价。[结果]室内卫生学指标中噪声及二氧化碳合格率分别为0.00%和24.07%。集中空调通风设备卫生学指标中可吸入颗粒物(PM10)及细菌总数合格率分别为52.78%和83.33%。空气中二氧化碳浓度与人员密度呈直线正相关,在人员密度相同的情况下,通风条件不同的场所空气中二氧化碳浓度差异有统计学意义(P0.01)。[结论]医院候诊输液区域噪声和二氧化碳问题最为突出,二氧化碳浓度与通风条件及人员密度密切相关。医院集中空调通风设备的卫生管理亟待规范。     

Indoor air quality in two urban elementary schools--measurements of airborne fungi, carpet allergens, CO2, temperature, and relative humidity

This article presents measurements of biological contaminants in two elementary schools that serve inner city minority populations. One of the schools is an older building; the other is newer and was designed to minimize indoor air quality problems. Measurements were obtained for airborne fungi, carpet loadings of dust mite allergens, cockroach allergens, cat allergens, and carpet fungi. Carbon dioxide concentrations, temperature, and relative humidity were also measured. Each of these measurements was made in five classrooms in each school over three seasons--fall, winter, and spring. We compared the indoor environments at the two schools and examined the variability in measured parameters between and within schools and across seasons. A fixed-effects, nested analysis was performed to determine the effect of school, season, and room-within-school, as well as CO2, temperature and relative humidity. The levels of all measured parameters were comparable for the two schools. Carpet culturable fungal concentrations and cat allergen levels in the newer school started and remained higher than in the older school over the study period. Cockroach allergen levels in some areas were very high in the newer school and declined over the study period to levels lower than the older school. Dust mite allergen and culturable fungal concentrations in both schools were relatively low compared with benchmark values. The daily averages for temperature and relative humidity frequently did not meet ASHRAE guidelines in either school, which suggests that proper HVAC and general building operation and maintenance procedures are at least as important as proper design and construction for adequate indoor air quality. The results show that for fungi and cat allergens, the school environment can be an important exposure source for children.     

An evaluation of the indoor air quality in bars before and after a smoking ban in Austin, Texas

This study assessed differences in the indoor air quality and occupancy levels in seventeen bars due to a city-wide smoking ban that took effect on September 1, 2005 in Austin, Texas, USA. We measured the following in each venue before and after the smoking ban: mean number of occupants, mean number of lit cigarettes, temperature, relative humidity, room volume, and PM(2.5), CO, and CO(2) concentrations. Additionally, VOC measurements were conducted at three of the venues. There was not a statistically significant change in occupancy, but the best estimate PM(2.5) concentrations in the venues decreased 71-99%, a significant reduction in all venues, relative to the pre-ban levels; CO concentrations decreased significantly in all but one venue; and concentrations of VOCs known to be emitted from cigarettes decreased to below the detection limit for all but two common compounds. These results suggest that the smoking ban has effectively improved indoor air quality in Austin bars without an associated decrease in occupancy.     

Air quality in a school with dampness and mould problems

An air quality monitoring campaign was carried out from the 13th to the 17th of January 2013 in a secondary school of the municipality of Anadia (Portugal) with dampness and mould problems. Continuous measurements of different particulate matter (PM) sizes [PM₁, PM_2.5, PM₄ and PM₁₀ and total suspended particles (TSP)], comfort parameters (temperature and relative humidity), CO, CO₂ and total volatile organic compounds were simultaneously carried out in a computer classroom, in the girl’s locker/shower room and outdoors. Low-volume samplers were used to collect PM₁₀ samples for subsequent determination of their carbonaceous content. Bacteria and fungi were collected by liquid impinger sampling and by direct scratching of surfaces. Temperature and relative humidity were far outside the comfort ranges in both rooms. Contrary to the locker/shower room, highly inefficient ventilation rates in the computer classroom, with occupancy always higher than 20 students, led to elevated CO₂ concentrations (>2250 mg m^?3). Much higher particle concentrations were observed in the locker room. Although not allowed, some smoking episodes in this indoor space may have contributed to particle concentrations up to 30 mg m^?3 and to indoor-to-outdoor ratios of 340. If the short smoking episodes are excluded, similar average PM₁₀ levels (<50 μg m^?3) are obtained for both rooms. Around 60 % of the total suspended particles are composed of submicrometric material. The concentrations of total culturable bacteria in the locker room, computer classroom and outdoors were, on average, 1038, 772 and 176 CFU m^?3, respectively. The corresponding fungi concentrations were 285, 542 and 125 CFU m^?3. In most cases, the concentrations of both, culturable bacteria and fungi, were above the legal limits (500 CFU m^?3). Fungi present in impinger samples and also those collected by direct scratching of surfaces were identified as belonging to the genera Alternaria, Aspergillus, Cladosporium and Penicillium, all of them potentially harmful to human health. A high degree of discomfort, insufficient ventilation in some microenvironments and the presence of allergenic bioaerosols at excessive levels indicate that the adoption of remedial actions is required.     

Perceptions of indoor air quality associated with ventilation system types in elementary schools

With the increased utilization of school buildings on a year-round basis, school indoor air quality has become a national concern. The purpose of this study was to evaluate possible associations between ventilation system type and occupant perception of indoor air quality. Staff (n = 403) from 12 schools completed a self-administered questionnaire. Carbon dioxide (CO2) levels, air exchange rates, and particle counts were also measured for each school. Schools with unit ventilator (UV) systems had the lowest mean CO2 level at 637 ppm, followed by the variable air volume (VAV) systems with 664 ppm, and constant volume (CV) systems with a mean of 703 ppm. Schools with UV systems had the lowest mean air exchange rate at 2.67 air changes per hour (ACH), followed by the VAV system type at 2.80 ACH and the CV system type at 4.61 ACH. Indoor versus outdoor particle ratios were calculated for each ventilation system type. Particles with aerodynamic diameters ranging from 0.1-1.0 microm had a geometric mean ratio ranging from 0.38 to 0.68; particles with aerodynamic diameters ranging from 1-3 microm had ratios ranging from 1.39 to 5.47, and particles with aerodynamic diameters greater than 3 microm had ratios ranging from 3.20 to 14.76. Schools using VAV systems had a significantly lower prevalence of red and watery eyes while schools with UV systems had an elevated prevalence of nasal congestion, sore throat, headache, and dustiness complaints. This increased prevalence of complaints in buildings with UV systems may be due to the increased particulate levels.     

某地铁站竣工耐室内化学性污染物监测与评价

目的对深圳某地铁站竣工时站厅、站台、室内空气化学性污染物进行卫生监测与评价,预防和控制污染物可能对乘客健康的危害。方法根据该地铁站厅、站台面积,采用随机抽样方法,每天分上、下午对室内空气化学性污染物进行连续3天的检测。结果12种化学性污染物3天检测结果的均值均无超标;站厅站台的PM10、站厅的苯、站台的TVOC合格率分别为85．O％、78．8％、91．7％、96.3％,其他污染物各检测点合格率均为100％;站厅和站台CO、CO2、SO2、NO2,站厅的甲醛,站台的笨、二甲苯的含量明显低于深圳市2004年18个地铁站的平均水平（P〈．05）。结论该地铁站竣工时站厅站台受化学性污染物污染的程度较轻,可能与改善通风和使用环保材料有关。     

Assessment of indoor air pollution in homes with infants

Infants spend most of their indoor time at home; however, residential air quality is poorly understood. We investigated the air quality of infants' homes in the New England area of the U.S. Participants (N = 53) were parents of infants (0-6 months) who completed telephone surveys to identify potential pollutant sources in their residence. Carbon monoxide (CO), carbon dioxide (CO(2)), particulate matter with aerodynamic diameter ≤0.5 μm (PM(0.5)), and total volatile organic compounds (TVOCs) were measured in 10 homes over 4-7 days, and levels were compared with health-based guidelines. Pollutant levels varied substantially across homes and within homes with overall levels for some homes up to 20 times higher than for other homes. Average levels were 0.85 ppm, 663.2 ppm, 18.7 μg/m(3), and 1626 μg/m(3) for CO, CO(2), PM(0.5), and TVOCs, respectively. CO(2), TVOCs, and PM(0.5) levels exceeded health-based indoor air quality guidelines. Survey results suggest that nursery renovations and related potential pollutant sources may be associated with differences in urbanicity, income, and presence of older children with respiratory ailments, which could potentially confound health studies. While there are no standards for indoor residential air quality, our findings suggest that additional research is needed to assess indoor pollution exposure for infants, which may be a vulnerable population.     

Oxidative DNA damage estimated by urinary 8-hydroxydeoxyguanosine and indoor air pollution among non-smoking office employees

This study investigated whether urinary 8-hydroxydeoxyguanosine (8-OHdG), a biomarker of oxidative stress, was associated with indoor air quality for non-smokers in high-rise building offices. With informed consents, urine samples from 344 non-smoking employees in 86 offices were collected to determine 8-OHdG concentrations. The concentrations of carbon dioxide (CO(2)) and total volatile organic compounds (TVOCs) in each office and outside of the building were simultaneously measured for eight office hours. The average workday difference between indoor and outdoor CO(2) concentrations (dCO(2)) was used as a surrogate measure of the ventilation efficiency for each office unit. The CO(2) levels in the offices ranged 467-2810ppm with a mean of 1170ppm, or 2.7 times higher than that in the outside air. The average urinary 8-OHdG levels among employees increased from 3.10 micro g/g creatinine, for those at the lowest tertile levels of both dCO(2) and TVOCs, to 6.27 micro g/g creatinine, for those at the highest tertile levels. Multivariate logistic regression analysis showed that the risk of having the urinary 8-OHdG level of greater than the median, 4.53 micro g/g creatinine, for participants was increased significantly at the highest tertile dCO(2) level of >680ppm (odds ratio (OR)=3.37, 95% confidence interval (CI)=1.20-9.46). The effect was significant at the middle tertile TVOCs level of 114-360ppb (OR=2.62, 95% CI=1.43-4.79), but not at the highest tertile. Inadequate ventilation in office increases the risk of building-related oxidative stress in non-smoking employees.     

Variation in indoor air pollutant concentrations with time in a newly constructed private house

An indoor air quality research project was conducted in a new private house built in January 1997 to investigate time course changes in formaldehyde concentrations during an 11-month period from April 1997 to February 1998. Indoor and outdoor concentrations of volatile organic compounds (VOCs) and nitrogen dioxide were also measured in August 1997 and February 1998. Indoor formaldehyde concentrations were measured 14 times (48 hrs sampling for each measurement) for 28 days in the living room, a bedroom and the kitchen in April '97. The concentrations exceeded the Japanese Government's guideline value of 0.08 ppm in 34 of the 42 (81.0%). Day to day variation in the formaldehyde concentration was found to be substantial, the range being between 0.073 and 0.232 ppm for the bedroom, for example. In June and August '97, values for 20 of 21 measurements exceeded the guideline, the results suggesting that indoor formaldehyde concentrations remain high until 7 months after the completion of construction. There were positive correlations between the formaldehyde concentrations in the living room and the kitchen and personal exposure levels to formaldehyde, the result indicating a direct influence of the home environment. The formaldehyde concentration in the living room also exhibited a positive correlation with the room temperature. Natural ventilation by opening windows was found to be effective for decreasing the concentration of formaldehyde in the indoor air. Indoor VOC concentrations decreased rapidly after the completion of construction except for that of toluene, which was higher than the outdoor concentration even after 7 months. Indoor concentrations of all of the VOCs were, however, found to be almost the same as those outdoor at the 13 month time point. Indoor nitrogen dioxide concentrations measured in the bedroom in winter (February '98) exceeded the Environmental Air Quality Standard in Japan, this result being considered due to use of an oil fan heater. These data suggest that personal exposure levels to formaldehyde and nitrogen dioxide are high in newly constructed private homes in Japan. In order to avoid prolonged exposure to high concentrations of indoor air pollutants, it is considered very important to take measures such as of use building materials with low formaldehyde emissions and to discontinue the use of oil fan heaters.     

An evaluation of ventilation system flow rates and levels of carbon dioxide,ambient temperature,and relative humidity in restaurants

Studies of the indoor air quality of restaurants have rarely focused on ventilation system performance in relation to air pollutants and climatic factors. This study was conducted in eight restaurants to examine this issue by determining the ventilation flow rates and the levels of carbon dioxide (CO2), ambient temperature, and relative humidity during at least one complete shift of serving a meal. The mean values of number of dining patrons, ventilation flow rates, and the levels of CO2, ambient temperature, and relative humidity were not significantly different in the nonsmoking dining rooms and the smoking dining rooms. The mean ventilation flow rates in individual restaurants ranged from 42-113 cubic feet per minute per person (cfm/person), overall exceeding the recommended lower limit of 30 cfm/person. The mean levels of CO2 in two restaurants (646 and 819 ppm) were below, and in the other six restaurants (ranging 1,012-1,820 ppm) were above the recommended upper limit of 1000 ppm. The levels of CO2 in each restaurant significantly correlated with the number of dining patrons and in four restaurants accumulated gradually over time. In the nonsmoking dining rooms, the levels of CO2 increased significantly as the ventilation How rates decreased. The mean ambient temperature in restaurants (ranging from 22 degrees C - 24 degrees C) were within the recommended range of 20 degrees C - 26 degrees C. The mean relative humidity in six restaurants (ranging from 46%-59%) were within the recommended upper limit of 60 percent, and in two restaurants (62% and 71%) were slightly higher than this recommended limit. It was concluded that although the mean ventilation flow rates in all restaurants exceeded the recommended value, the design of the ventilation system or the distribution of air flow rate in some sections of restaurants were not appropriate to keep the levels of CO2 and relative humidity at some measurement locations below the recommended limits.     

Assessment of Fine Particulate Matter and Gaseous Pollutants in Workplace Atmosphere of Metallic Industry

In the present study, we measured the concentrations of fine particulate matter (PM_2.5), carbon dioxide (CO₂), carbon monoxide (CO) and volatile organic carbon (VOC) in the indoor air of the manufacturing department of a metal factory. The daily average PM_2.5 concentration ranged between 86.3 and 404.9 μg/m³. The isolation of the manufacturing machines reduced. PM_2.5 concentration between 2.5 and 8.8 fold. At the seven measurement points, daily concentrations ranged from 576.7 to 623.4 ppm for CO₂, 0.8 to 15.8 ppm for CO, and 0 to 0.58 ppm for VOC, respectively.     

Indoor air quality and occupational exposures at a bus terminal

This article presents an assessment of indoor air quality at a bus terminal. For this purpose, field surveys were conducted, and air samples were collected and analyzed for the presence of selected indoor air quality indicators. Mathematical modeling was performed to simulate bus emission rates, occupational exposure, and ventilation requirements to maintain acceptable indoor air quality. A sensitivity analysis based on literature-derived emission rates estimates was conducted to evaluate the effect of seasonal temperature changes within the terminal. Control measures to improve indoor air quality at the terminal are also outlined. While carbon monoxide concentrations were below the corresponding American Conference of Governmental Industrial Hygienists' (ACGIH) standards under normal operating conditions, they exceeded the 8-hr recommended average standard at peak hours and the World Health Organization (WHO) standard at all times. Total suspended particulates levels, on the other hand, were above the 24-hr American Society of Heating, Refrigerating and Air Conditioning Engineers' (ASHRAE) standard. Carbon monoxide emission rates that were estimated using the transient mass balance model correlated relatively well with those reported in the literature. Modeling results showed that the natural ventilation rate should be at least doubled for acceptable indoor air quality. While pollutant exposure levels depended on the individual activity patterns and the pollutant concentration, pollutant emissions rates within the terminal were affected mostly by the temperature with a 20-25 percent variation in carbon monoxide levels due to changes in seasonal temperatures.