Required Ventilation Rate Research Articles

Uncertainty Distribution of Air Infiltration Rates of Thai Detached Homes for Energy Model

Air infiltration through building envelope is considered as a path of outdoor air ventilation in modern Thai detached homes where there is no outdoor air intake in an air condition unit. At present, there are limited studies of air infiltration rate through building envelope for Thai homes and such few studies are insufficient for establishing a database of air infiltration rate for evaluating home energy performance. This present study used a multi-zone airflow model to calculate air infiltration rates in 134 homes from 137 housing development projects located in suburban areas near Bangkok. The calculated air exchange rate (air infiltration) ranged from 0.33-0.58 h-1 with an average value of 0.43 h-1 (s.d. = 0.04). Compared to the ventilation standards, the calculated air exchange rates were approximately 1.7 times greater than the required ventilation rates defined by the ASHRAE Standard 62.2 (2007) and 93% of those achieved the required ventilation rate prescribed in the Thai Building Control Act B.E. 2522 (2015). Consequently, it has a potential to reduce air infiltration rate for modern Thai detached home to save home energy consumption. The default air infiltration rate typically used in energy models provided a maximum input error ranged from 7-65% when compared to the calculated air infiltration rates.

A natural ventilation wind tower with heat pipe heat recovery for cold climates

Commercial wind towers are passive ventilation technology based on traditional wind towers of the Middle East. Typical operation of wind towers in cold – mild climates is generally limited to summer-seasons as the outdoor air is too cold to be introduced into spaces for the majority of the year. In addition, the use of natural ventilation solutions has been seen to increase heat loss in buildings and lead to increased energy cost. Wind towers are normally shut down for the sake of avoiding indoor heating energy losses during winter months. Consequently, the concentration of pollutants has seen to rise above the guideline levels, which can lead to ill health. To improve the year-round capabilities of wind towers, a heat recovery system utilising the combination of heat pipes and heat sink was incorporated into a multi-directional wind tower. This study investigates the potential of this concept through the use of numerical analysis and wind tunnel experiments for validation. The findings showed that the wind tower with heat pipes was capable of meeting the required ventilation rates above an inlet air velocity of 1 m/s. In addition to sufficient ventilation, the integration of heat pipes had a positive effect on thermal performance of the wind tower; it raised the supply air by up to 4.5 K. The technology presented here is subject to a patent application (PCT/GB2014/052263).

심부 석탄광산의 환기시스템 최적화 연구

Abstract This paper aims for the ultimate goal to optimize the work place environment through assuring the optimal required ventilation rate based on the analysis of the airflow. The working environment is deteriorated due to a rise in temperature of a coal mine caused by increase of its depth and carriage tunnels. To improve the environment, the ventilation evaluation on J coal mine is carried out and the effect of a length of the tunnel on the temperature to enhance the ventilation efficiency in the subsurface is numerically analyzed. The analysis shows that J coal mine needs 17,831 m 3 /min for in-flow ventilation rate but the total input air flowrate is 16,474 m 3 /min, 1,357 m 3 /min of in-flow ventilation rate shortage. The temperatures were predicted on the two developed models of J mine, and VnetPC that is a numerical program for the flowrate prediction. The result of the simulation notices the temperature in the case of developing all 4 areas of -425ML as a first model is predicted 29.30 at the main gangway 9X of C section and in the case of developing 3 areas of -425ML excepting A area as a second model, it is predicted 27.45 Celsius degrees.Key words Coal mine, Artificial Neural Network, Temperature prediction, Ventilation system초 록 본 연구에서는 적정 소요환기량의 확보를 통한 갱내 환경의 최적화를 위한 기초연구로 갱내 소요환기량을 추정하였다. 채굴의 심부화 및 운행갱도의 증가로 인한 온도상승으로 작업환경이 점차 악화되는 광산에서 작업환경의 개선을 위하여 J광업소를 대상으로 환기평가를 하였으며 갱내의 환기효율을 증가시키기 위하여 갱도의 길이에 따른 온도에 대한 효과를 수치 해석하였다 . 연구결과 J광업소의 소요환기량은 17,831 m

Engineering control of respiratory infection and low-energy design of healthcare facilities

Indoor microorganisms and infection have become an emerging direction in indoor air quality research science. Airborne droplet nuclei can serve as carriers of respiratory infectious diseases. The study of expiratory droplets and their exposure control has received particular attention since the 2003 severe acute respiratory syndrome epidemics and the 2009 influenza pandemics. Little is known about how effective the commonly used indoor environment control strategies are for infection control. Significant questions also exist on the ventilation requirements for airborne infection control. There is a broad range of relevant important issues, including the exposure risk, and effective control methods in various indoor settings, such as hospitals, homes, schools, and offices. What is known is that the minimum required ventilation rate for infection control in hospitals can be much higher than the general health and comfort requirement in homes and offices. This has resulted in significant energy-efficiency issues in healthcare facilities. This review considers the current knowledge on airborne transmission of infection and the potential implications of a move to low-energy design, particularly in hospitals, on the risk of infection. The review outlines active research and development on reducing hospital energy use while improving infection control and discusses the potential for conducting “clinical trials” to gain the necessary evidence to support changes in hospital ventilation design.

Practical approaches to determine ventilation rate for offices while considering physical and chemical variables for building material emissions

Indoor air pollutants in offices can be attributed to various sources, including building materials, consumer products, and exhalation from occupants. The required ventilation rate for offices can be determined by estimating the majority of emissions originated from building materials, as an additional determinant factor for ventilation rate, with the assumption of constant ventilation with 100% outdoor air, uniform indoor mixing, and no chemical reactions. In this paper, the validity of these assumptions was investigated by incorporating the effects of various physical and chemical factors in determining material emissions and ventilation rates. Three physical factors investigated were recirculation ventilation, intermittent ventilation and pollutant distribution. Simplified methods using correction factors were proposed to revise the ventilation rate and validated by emission modeling and CFD method. In addition, three chemical factors were discussed. First, 28 building materials were selected from the NRC database and each was subject to determining the ventilation rate. As a result, 28 leading pollutants that are likely to determine the ventilation rate were obtained. Because most of the leading pollutants are reactants rather than products of indoor air reactions, it was concluded that the current ventilation rate determining methods should still be applicable. Additionally, a correction method was proposed for a reaction product such as formaldehyde. Second, the methods to revise ventilation rate based on temperature variation and pollutant concentration in outdoor air were proposed. This study showed that ventilation rate for offices could be determined based on building material emissions in more realistic ventilation and environmental conditions.

Rampway 설치 석회석 광산내 환기 현황 및 열환경 분석 사례연구

As more diesel engines have been employed in underground limestone mines with large cross section, underground space environment is worsened by diesel exhausts and heat flow. This paper aims for the ultimate goal to optimize the work place environment through assuring the optimal required ventilation rate based on the analysis of the airflow, diesel exhaust gas concentrations and the effects of mechanization and deepening working face on temperature and humidity. Due to the insufficient capacity of the main exhaust fan and poor airway management, stagnant airflows were observed at various locations, while the flow direction was reversed instantly with passing diesel equipment and the flow reversal was also made by the seasonal variation of the outside surface weather. During the loading operation, CO concentration measurements were found to be frequently higher than the threshold limit of 50 ppm, and most of the measurements during drilling and loading operations shows even more serious levels surpassing the permissible limit of 3 ppm. The actual ventilation quantity was considerably less than the required quantity estimated by the mine health and safety law, and this shortage problem was less serious in colder winter showing more effectiveness of the natural ventilation.

Determining Optimum Configurations of Solar Collecting Window Systems for Double Skin Envelope

This study investigates the influence of cavity depth and the conditions of louvers on indoor thermal environments to propose optimum configurations of solar collecting window systems that can be effectively applied to double skin envelopes. Field measurements were performed for a reduced-scale mock-up model to represent the analysis results for a full-scale model. Computer simulations were performed using computational fluid dynamics (CFD) under a variety of cavity and horizontal louver conditions to validate the results from the field measurements. Two theoretical computation models, namely the k-e RNG and k-e standard models, were applied to the simulations.The results of field measurements imply that a cavity depth of 0.2 m was most effective in supplying air from a cavity to an indoor space with the required velocity and temperature. The validated computer simulation results imply that the k-e RNG model was more effective than the k-e standard model in predicting the properties of airflow in cavities where turbulent patterns occur due to the buoyancy effect.According to the analysis based on the k-e RNG model, a cavity depth of 0.2 m appeared to be optimum to achieve the required ventilation rates with energy savings. The temperature and velocity of air supplied from the cavity to the indoor space was most effective when the tilt angle of the horizontal louver was 45o. While airflow passed through the cavity exchanging heat with the louvers, it was not significantly blocked by the tilted louvers. This improved natural convection and ventilation rates in the cavity. This study suggests that the solar collecting window system could be effectively applied to building envelopes in winter.

Ventilation rates in the bedrooms of 500 Danish children

The ongoing “Indoor Environment and Children’s Health” (IECH) study investigates the environmental risk factors in homes and their association with asthma and allergy among children aged 1–5 years. As part of the study, the homes of 500 children between 3 and 5 years of age were inspected. The selected children included 200 symptomatic children (cases) and 300 randomly selected children (bases). As part of the inspection, the concentration of carbon dioxide in the bedrooms of the children was continuously measured over an average of 2.5 days. The ventilation rates in the rooms during the nights when the children were sleeping in the room were calculated using a single-zone mass balance for the occupant-generated CO 2. The calculated air change rates were log-normally distributed ( R 2 > 0.98). The geometric mean of the air change rates in both the case and the base group was 0.46 air changes per hour (h −1; geom. SD = 2.08 and 2.13, respectively). Approximately 57% of both cases and bases slept at a lower ventilation rate than the minimum required ventilation rate of 0.5 h −1 in new Danish dwellings. Only 32% of the bedrooms had an average CO 2 concentration below 1000 ppm during the measured nights. Twenty-three percent of the rooms experienced at least a 20-minute period during the night when the CO 2 concentration was above 2000 ppm and 6% of the rooms experienced concentrations above 3000 ppm. The average air change rate was higher with more people sleeping in the room. The air change rate did not change with the increasing outdoor temperature over the 10-week experimental period. The calculation method provides an estimate of the total airflow into the bedroom, including airflows both from outdoors and from adjacent spaces. To study the accuracy of the calculated air change rates and their deviation from the true outside air change rates, we calculated CO 2 concentrations at different given air change rates using an indoor air quality and ventilation model (Contam). Subsequently we applied our calculation procedure to the obtained data. The air change rate calculated from the generated CO 2 concentrations was found to be between 0% and 51% lower than the total air change rate defined in the input variables for the model. It was, however, higher than the true outside air change rate. The relative error depended on the position of the room in relation to the adjacent rooms, occupancy in the adjacent room, the nominal air change rate and room-to-room airflows.

Estimation of appropriate capacity of ventilation system based on the air infiltration rate in Korean classrooms

The appropriate capacity of a ventilation system based on the air infiltration rate in Korean classrooms is investigated to obtain optimal design conditions for ventilation systems. Theoretical and the experimental analyses are performed to estimate the proper ventilation capacity with a consideration of the air infiltration, the indoor air quality, and the ventilation rate. The air infiltration rate of the classroom is measured within the range of 0.5–1.5 1/h, and the required ventilation rate should be decided not by the contaminants (Formaldehyde and TVOC) emitted from the construction materials but by the carbon dioxide (CO2) emitted from human breath. The appropriate capacity of the ventilation system based on the air infiltration rate of the classroom for elementary schools is 500CMH and for middle and high schools is 800 CMH. The measured and the estimated values of CO2 concentrations are very similar and the modeling equation of CO2 concentration can be used as a reference for the proper estimation of ventilation rate in Korean schools.

휴대용 가스렌지 연소에 의한 공기오염물질의 발생량 및 실내환경의 필요 환기량

A series of source tests were conducted to characterize emissions of nitrogen oxide(NOx, NO, <TEX>$NO_2$</TEX>), carbon mon oxide(CO), carbon dioxide<TEX>$(CO_2)$</TEX> and total VOCs from portable combustion devices in steady-state using well-mixed chamber. Since use of portable gas range is widespread in houses and restaurants in Korea, it is important to characterize the emission of air pollutants and suggest optimum ventilation rate. Ranges of emission rates of air pollutants from portable gas ranges were <TEX>$NO \;0.551\sim0.939mg/hr,\;NO_2\;0.354\sim1.080mg/hr,\;NO_x\;1.207\sim1.631mg/hr,\;CO\;1.389\sim4.21mg/hr,\;CO_2\;2426.823\sim2973.495mg/hr$</TEX>, and VOCs <TEX>$0\sim0.119mg/h$</TEX>. Mean of personal exposure and indoor environment level of <TEX>$NO_2$</TEX> by combustion of portable gas range were 74.7 ppb and 65.4 ppb, respectively, suggesting persons using portable gas range in houses and restaurants might be highly exposed. Required ventilation rate to control the air pollutants emitted from portable gas range was maximumly <TEX>$3.131m^3/hr$</TEX> on the basis of <TEX>$NO_2$</TEX> indoor air quality standard.

ENERGY BALANCE MODEL FOR NATURAL VENTILATION OF GREENHOUSES

Energy balance methods currently used to estimate the natural ventilation rate of greenhouses ( ma  ) assume that the input energy to the greenhouse is the transmitted solar radiation. An average value for the cover transmittance ( c  ) is usually used to estimate this energy. However, this estimate includes a large error due to the spatial variation of c  in the greenhouse. These methods also give negative values of ma  at low solar radiation levels (e.g. in the morning and afternoon). The purpose of this study was to develop a simplified energy balance model to estimate the value of ma  precisely. In this model, all modes of energy were treated at the outer surface of the cover to avoid the error caused by using an average value of c  . Required environmental parameters to be used in the model were measured inside and outside a single-span glass-covered greenhouse with a floor area of 26 m2 located in the Tokyo area, Japan during four sunny days (Sept. 29 to Oct. 2., 2005) The greenhouse was naturally ventilated using two roof ventilators (0.6 m  5 m). Diurnal variations of ma  were estimated and compared with the results of other models and showed the necessity of applying the present model. The estimated value of ma  was in the range between 0.11 kg s -1 and 2.25 kg s-1 and these results were in accordance with those measured and reported in the literature. The results also confirmed that outside wind at a speed less than 2.5 m s-1 has no significant effect on the value of ma  and the value of ma  resulting from the greenhouse thermal balance depends mainly on temperature difference of air between inside and outside the greenhouse ( T ). A linear correlation between ma  and T was provided that can be used to estimate the required ventilation rate to maintain the air temperature in the greenhouse at a desired level.

Wind Pressure Coefficients for Different Building Configurations with and without an Adjacent Building

The design protocol for wind-driven cross ventilation in buildings should include two processes, namely the determination of required ventilation rate to reduce the room temperature and the prediction of the ventilation rate resulting from the arrangement of openings and wind pressure on those. Computer fluid dynamic techniques (CFD) have the potential to be a useful tool in such calculations but another more practical way is the airflow network model combined with the wind pressure coefficient (Cp) values for buildings with different shapes and surrounding conditions. The authors have conducted a series of wind tunnel experiments using scale building models to obtain the wind pressure coefficient distribution on the building envelope and have developed a database to be used as input data for network simulation programs. In the estimation of Cp, one of the challenging problems is the effect of surrounding obstacles such as adjacent buildings. There are some works that take this effect into consideration, by making corrections to the wind pressure coefficients of an isolated building. Firstly, this paper applies such correction knowledge and secondly, tries to draw some general rules, which can be applied when estimating the wind pressure coefficients for a building which is surrounded by adjacent buildings.

Summary of human responses to ventilation.

It is known that ventilation is necessary to remove indoor-generated pollutants from indoor air or dilute their concentration to acceptable levels. But as the limit values of all pollutants are not known the exact determination of required ventilation rates based on pollutant concentrations is seldom possible. The selection of ventilation rates has to be based also on epidemiological research, laboratory and field experiments and experience. The existing literature indicates that ventilation has a significant impact on several important human outcomes including: (1) communicable respiratory illnesses; (2) sick building syndrome symptoms; (3) task performance and productivity, and (4) perceived air quality (PAQ) among occupants or sensory panels (5) respiratory allergies and asthma. In many studies, prevalence of sick building syndrome symptoms has also been associated with characteristics of HVAC-systems. Often the prevalence of SBS symptoms is higher in air-conditioned buildings than in naturally ventilated buildings. The evidence suggests that better hygiene, commissioning, operation and maintenance of air handling systems may be particularly important for reducing the negative effects of HVAC systems. Ventilation may also have harmful effects on indoor air quality and climate if not properly designed, installed, maintained and operated. Ventilation may bring indoors harmful substances or deteriorate indoor environment. Ventilation interacts also with the building envelope and may deteriorate the structures of the building. Ventilation changes the pressure differences across the structures of building and may cause or prevent infiltration of pollutants from structures or adjacent spaces. Ventilation is also in many cases used to control the thermal environment or humidity in buildings. The paper summarises the current knowledge on positive and negative effects of ventilation on health and other human responses. The focus is on office-type working environment and residential buildings. The review shows that ventilation has various positive impacts on health and productivity of building occupants. Ventilation reduces the prevalence of airborne infectious diseases and thus the number of sick leave days. In office environment a ventilation rate up to 20-25 L/s per person seem to decrease the prevalence of SBS-symptoms. Air conditioning systems may increase the prevalence of SBS-symptoms relative to natural ventilation if not clean. In residential buildings the air change rate in cold climates should not be below app. 0.5 ach. Ventilation systems may cause pressure differences over the building envelope and bring harmful pollutants indoors.

SE—Structures and Environment: The Penman–Monteith Evapotranspiration Equation as an Element in Greenhouse Ventilation Design

Transpiration is a major cooling mechanism of greenhouse crop canopies. The larger this energy dissipation component, the smaller the required ventilation rate. The evaporation coefficient, namely the fraction of the radiation load dissipated as latent heat, is therefore an important ventilation design parameter, of which designers have currently no more than qualitative knowledge. In an attempt to overcome this difficulty, the present study proposes to incorporate the Penman–Monteith evapotranspiration equation into the standard ventilation design formula. With this modification the design adapts automatically not only to different radiation loads and temperatures, but also to different humidity conditions. The new design formula can be modified for greenhouses with an evaporative cooling system, and either air temperature or crop temperature may be used as the design criterion. The applicability of this approach depends on the availability of reliable bulk Penman–Monteith coefficients, which may be improved by a joint analysis of data from different climatic regions.

Trends in cabin air quality of commercial aircraft: industry and passenger perspectives.

The small air space available per person in a fully occupied aircraft passenger cabin accentuates the human bioeffluent factor in the maintenance of air quality. The accumulation of carbon dioxide and other contributions to poor air quality that can occur with inadequate ventilation, even under normal circumstances, is related to the volume of available air space per person and various ventilation rates. This information is compared with established air quality guidelines to make specific recommendations with reference to aircraft passenger cabins under both normal and abnormal operating conditions. The effects of respiration on the air quality of any enclosed space from the respiration of a resting adult are estimated using standard equations. Results are given for different volumes of space per person, for zero air exchange, and for various air change rates. The required ventilation rates estimated in this way compared closely with results calculated using a standard empirical formula. The results confirm that the outside air ventilation required to achieve a target carbon dioxide concentration in the air of an occupied enclosed space remains the same regardless of the volume of that space. The outside air ventilation capability of older and more recent aircraft is then reviewed and compared with the actual measurements of cabin air quality for these periods. The correlation between calculated and measured aircraft cabin carbon dioxide concentrations from other studies was very good. Respiratory benefits and costs of returning to the 30% higher outside air ventilation rates and 8% higher cabin pressures of the 1960s and 1970s are outlined. Consideration is given to the occasional occurrence of certain types of aircraft malfunction that can introduce more serious contaminants to the aircraft cabin. Recommendations and suggestions for aircraft builders and operators are made that will help improve aircraft cabin air quality and the partial pressure of oxygen that is available to passengers at minimal cost. Also suggested are some measures that passengers can take to help improve their comfort and decrease their risk of illness, particularly on long-haul flights.

Alternative Design Formulae for the Ventilation Rate of Greenhouses

A fresh look at a standard design formulae for ventilation of greenhouses is presented. The new approach emphasizes crop-canopy temperature rather than air temperature and covers situations with positive as well as negative ventilation Bowen ratios (ratio of sensible to latent heat). The latter situation is characteristic of arid conditions, and is the result of intense evapotranspirational cooling on hot, dry days. Two design formulae are considered, depending on the availability of experimental data for parameter estimation. First, a midday crop-in-greenhouse model is developed. It relates canopy temperature to environmental and operational conditions and can be used, at least in principle, to find the dependence of stomatal and aerodynamic conductances on the ventilation rate. If canopy-temperature data are not available, but transpiration data make it possible to develop a simple predictive formulae, representative values of the stomatal and aerodynamic conductances can be obtained. These can then be used to calculate the required ventilation rate. The procedure is illustrated with data from a temperate-maritime climate. Some improvement over the standard approach can be made even with just standard environmental data. With these an empirical relationship may be found between the Bowen ratio and the temperature rise in the greenhouse. The Bowen ratio is then used in the revised design formulae. This approach removes some of the guesswork currently involved in selecting the evaporation coefficient for the standard design formulae. This procedure is illustrated with data sets from mediterranean locations, which also demonstrate the effect of evaporative cooling.

95/05198 Reducing energy costs using run-around systems

This article describes how run-around systems reduce costs by efficient energy recovery from ventilation air and still provide required ventilation rates. Air heating usually constitutes 25% to 50% of the heating loads in commercial buildings, while cooling loads are satisfied entirely by air. Prior to the introduction of ASHRAE Standard 62-1989, more than 95% of commercial buildings did not use any means to reduce air heating and cooling loads by exchanging heat between the building exhaust and outside supply air. The run-around system does not require the exhaust coil near the supply coil because the energy is transferred by a coupling fluid that is pumped and controlled independently. Energy exchange between exhaust and supply air can now have overall effectiveness values much higher than in the past (50% or less) by using run-around coil-tube heat exchanger systems that are accurately designed for maximum cost-effective performance.

On ventilation design for underground car parks

Ventilation design for underground car parks is studied, first through a brief review of the ventilation requirement. Carbon monoxide concentration is believed to be the most important chemical species to be considered. Some results on field measurement of underground car parks reported in the literature are reviewed. The well-mixed model, which is a basic design model for studying the transient variation of carbon monoxide concentration, is described. The model is then revised to describe multiple sources of emission for several cars staying in a car park with their internal combustion engines operating. Two mixing models proposed by Sandberg 1981)—Model 1, based on a displacement ventilation system and Model 3, based on a ventilation system with a short-circuiting air flow path—are applied to study the ventilation design in car parks. The technique of computational fluid dynamics is used to verify those existing models and then to compute the mixing factors concerned. Key system performance parameters are calculated, and a set of graphs relating those system performance parameters with the input design data is presented. These graphs can be used for designing the required ventilation rate for the system under different carbon monoxide loads. Eight local car parks are surveyed to illustrate the application of the model. Field measurement data on underground car parks, as described above, are reviewed and applied to justify the mixing models.

Assessment of Multiple Markers of Environmental Tobacco Smoke (ETS) in Controlled, Steady-State Atmospheres in a Dynamic Test Chamber

Controlled test atmospheres of sidestream and mixed mainstream! sidestream tobacco smoke were produced in a dynamic test chamber of 16.9 m3 volume. University of Kentucky 1R4F research cigarettes were automatically smoked by a Borgwaldt smoking machine. Different target levels of smoke were attained by varying the number of cigarettes being smoked (one or two cigarettes continuously) and dilution airflow through the chamber (1.6 to 7.4 m3/min). For each level, a “smoke index” was calculated as the number of cigarettes being smoked divided by the dilution flow rate. Ultraviolet light-absorbing particulate matter (UVPM); aerosol counts and size distribution; and concentrations of CO, NO2, NH3, formaldehyde, acetaldehyde, acrolein, and nicotine were determined in the test atmospheres and background dilution air. Parameters exhibiting the highest correlations with smoke index (r2 > 0.98) included UVPM, aerosol counts, formaldehyde, and acetaldehyde. The other parameters were also highly correlated with r2 > 0.9 in each case. Differences in concentration for sidestream and mixed mainstream/sidestream atmospheres were statistically significant for acetaldehyde, formaldehyde, and CO; in each case the level was higher in mixed mainstream/sidestream smoke. These results demonstrate the utility of employing multiple markers for assessment of environmental tobacco smoke levels and for dichotomizing the contributions of sidestream and mainstream smoke to these levels. The generation factors developed in this work can be used for estimating required ventilation rates for attainment of target air quality conditions in smoking rooms.

Assessment of multiple markers of environmental tobacco smoke (ETS) in controlled, steady-state atmospheres in a dynamic test chamber.

Controlled test atmospheres of sidestream and mixed mainstream/sidestream tobacco smoke were produced in a dynamic test chamber of 16.9 m3 volume. University of Kentucky 1R4F research cigarettes were automatically smoked by a Borgwaldt smoking machine. Different target levels of smoke were attained by varying the number of cigarettes being smoked (one or two cigarettes continuously) and dilution airflow through the chamber (1.6 to 7.4 m3/min). For each level, a "smoke index" was calculated as the number of cigarettes being smoked divided by the dilution flow rate. Ultraviolet light-absorbing particulate matter (UVPM); aerosol counts and size distribution; and concentrations of CO, NO2, NH3, formaldehyde, acetaldehyde, acrolein, and nicotine were determined in the test atmospheres and background dilution air. Parameters exhibiting the highest correlations with smoke index (r2 > 0.98) included UVPM, aerosol counts, formaldehyde, and acetaldehyde. The other parameters were also highly correlated with r2 > 0.9 in each case. Differences in concentration for sidestream and mixed mainstream/sidestream atmospheres were statistically significant for acetaldehyde, formaldehyde, and CO; in each case the level was higher in mixed mainstream/sidestream smoke. These results demonstrate the utility of employing multiple markers for assessment of environmental tobacco smoke levels and for dichotomizing the contributions of sidestream and mainstream smoke to these levels. The generation factors developed in this work can be used for estimating required ventilation rates for attainment of target air quality conditions in smoking rooms.