Development of a field test method to evaluate gaseous air cleaner performance in a multizone building

The performance of gaseous air cleaners for commercial and residential buildings has typically been evaluated using test protocols developed for a controlled laboratory chamber or a test duct. It is currently unknown how laboratory measurements relate to the actual performance of an air cleaner installed in a real building. However, to date, there are no air cleaner field test protocols available, thereby limiting the existing field data. The National Institute of Standards and Technology (NIST) has conducted a series of experiments to support test procedure development for evaluating the installed performance of gaseous air cleaning equipment, as well as metrics for characterizing field performance. To date, over 100 experiments have been completed, of which 23 portable air cleaner experiments and 6 in-duct air cleaner experiments are described in this paper. Tests were conducted in a finished three-bedroom/two-bathroom manufactured house equipped with several gas chromatographs to semi-continuously measure air change rates and volatile organic compound concentrations. Experimental variables included air cleaner location, isolation of zones by closing doors, and contaminant source location. For each experiment, air cleaner removal of decane was directly measured using the air cleaner inlet and outlet concentrations, as well as with mass balance analyses using measured room concentrations. With a verified mass balance model, a field performance metric was developed to compare installed whole-building performance to the performance predicted by a laboratory result. The results provide insight into the protocols and metrics that might prove useful for characterizing the field performance of air cleaners as well as the impact of air cleaner removal on zonal concentration levels in a variety of situations.     

An experimental study of air entrainment and oxygen transfer at a water jet from a nozzle with air holes.

An adequate supply of dissolved oxygen is important in natural rivers and in some water treatment processes. The dissolved oxygen concentration can be enhanced by entraining air bubbles in a receiving pool. When a water jet impinges a receiving pool at rest, air bubbles may be entrained and carried away below the pool free surface. This process is called plunging water jet entrainment and aeration. This paper describes an experimental study of the air entrainment rate and oxygen transfer efficiency of circular nozzles with and without air holes. In particular, the effect of varying the number, positions, and open/close status of the air holes is investigated. A negative pressure occurred depending on the air holes opened on the circular nozzles. This phenomenon affected the water jet expansion, water jet shape, air entrainment, and bubble penetration depth and, hence, the oxygen transfer efficiency. It was demonstrated that the air entrainment rate and the oxygen transfer efficiency of the circular nozzles with air holes were better than those of the circular nozzles without air holes. Therefore, adding air holes to a simple, circular nozzle could lead to a significantly increased air entrainment rate and oxygen transfer efficiency.     

SAGA: a decision support system for air pollution management around a coal-fired power plant

Air quality models are currently feasible approaches to prevent air pollution episodes. From one of the first source-oriented modelling approaches for air pollution forecasting (Souto et al., 1994, 1996, 1998), a new decision support system for air quality management, SAGA, was developed to provide support to As Pontes Power Plant (APPP) staff. SAGA can provide air pollution forecasts and manage meteorological and air quality measurements. Power plant decisions are supported by the results of a non-hydrostatic meteorological model (ARPS, Xue et al., 2001) to produce Meteorological Forecasts (MFs), and to be coupled to different Lagrangian dispersion models.     

Progress Toward a Uniform Air Pollution Index

Recently, various authors^1–4 have indicated that a need exists to establish a uniform air pollution index for communities throughout the nation.Although the literature reveals several attempts to develop air pollution indices,^5–7 none of these indices has received widespread acceptance by state and local air pollution control agencies, probably because none has received the active support or endorsement of the federal government. We now wish to report that significant progress has been made at the federal level toward the goal of a recommended national air pollution index.     

Concentration of tetrachloroethylene in indoor air at a former dry cleaner facility as a function of subsurface contamination: a case study

A field study was performed to evaluate indoor air concentrations and vapor intrusion (VI) of tetrachloroethylene (PCE) and other chlorinated solvents at a commercial retail site in Dallas, TX. The building is approximately 40 yr old and once housed a dry cleaning operation. Results from an initial site characterization were used to select sampling locations for the VI study. The general approach for evaluating VI was to collect time-integrated canister samples for off-site U.S. Environmental Protection Agency Method TO-15 analyses. PCE and other chlorinated solvents were measured in shallow soil gas, subslab soil-gas, indoor air, and ambient air. The subslab soil gas exhibited relatively high values: PCE < or =2,600,000 parts per billion by volume (ppbv) and trichloroethylene < or =170 ppbv. The attenuation factor, the ratio of indoor air and subslab soil-gas concentrations, was unusually low: approximately 5 x 10(-6) based on the maximum subslab soil-gas concentration of PCE and 1.4 x 10(-5) based on average values.     

The state of ambient air quality in Pakistan—a review

Background and purpose  

Pakistan, during the last decade, has seen an extensive escalation in population growth, urbanization, and industrialization, together with a great increase in motorization and energy use. As a result, a substantial rise has taken place in the types and number of emission sources of various air pollutants. However, due to the lack of air quality management capabilities, the country is suffering from deterioration of air quality. Evidence from various governmental organizations and international bodies has indicated that air pollution is a significant risk to the environment, quality of life, and health of the population. The Government has taken positive steps toward air quality management in the form of the Pakistan Clean Air Program and has recently established a small number of continuous monitoring stations. However, ambient air quality standards have not yet been established. This paper reviews the data being available on the criteria air pollutants: particulate matter (PM), sulfur dioxide, ozone, carbon monoxide, nitrogen dioxide, and lead.     

Quantification and analysis of airborne bacterial characteristics in a nursing care institution

Indoor air quality has become a critical issue because people spend most of their time in the indoor environment. The factors that influence indoor air quality are very important to environmental sanitation and air quality improvement. This study focuses on monitoring air quality, colony counts, and bacteria species of the indoor air of a nursing care institution. The regular colony counts in two different wards range from 55 to 600 cfu m(-3) Regression analysis results indicate that the bacterial colony counts have close correlation with relative humidity or carbon dioxide (CO2) but not with carbon monoxide (CO) or ozone (O3). Real-time PCR was used to quantify the bacterial pathogens of nosocomial infection, including Acinetobacter baumannii, Citrobacter freundii, Escherichia coli, Klebsiella pneumoniae, and methicillin-sensitive Staphylococcus aureus. The most abundant bacteria species in the air of the nursing care institution is E. coli.     

Thermal and air flow characteristics in a deep pedestrian canyon under hot weather conditions

The present paper reports the results of a specific experiment carried out in a deep pedestrian canyon in Athens, Greece. The air flow inside and outside the canyon as well as the air and surface temperatures inside the canyon are measured for a period of seven continuous days during the whole day and night period. The air flow characteristics inside the canyon are analyzed. For perpendicular wind speeds, the air flow inside the canyon is characterized by either a circulatory vortex driven by the ambient air flow or a double vortex flow where the upper one is driven by the ambient air flow and the lower one is driven in the opposite direction by the circulation above. When the ambient air blows parallel to the canyon, the measured wind data inside the canyon indicate a flow in the same direction. When the air flows at a certain angle to the canyon axis, the measured data indicate that a spiral vortex is induced along the canyon length. The spatial and temporal variation of the surface and air temperature distribution inside the canyon is analyzed. The heat island intensity in the canyon is estimated based on measurements from a reference station.     

A comparison of air quality indices for a port and harbour region in India

The present paper discusses and compares four different air quality indices, viz. arithmetic, multiplicative, unweighted arithmetic, and unweighted multiplicative, which were considered for characterising the coastal air quality at the Jawaharlal Nehru Port, Mumbai, India. Suspended particulate matter, oxides of nitrogen, and sulphur dioxide were used as the parameters of air quality indices. Value function graphs for above-mentioned variables were developed using Indian ambient air quality standards for different areas. Product moment correlation coefficients for various air quality indices were determined using the SPSS software package to evaluate correlation among various indices.     

Development of a GIS-based decision support system for urban air quality management in the city of Istanbul

A decision support system has been developed for urban air quality management in the metropolitan area of Istanbul. The system is based on CALMET/CALPUFF dispersion modeling system, digital maps, and related databases to estimate the emissions and spatial distribution of air pollutants with the help of a GIS software. The system estimates ambient air pollution levels at high temporal and spatial resolutions and enables mapping of emissions and air quality levels. Mapping and scenario results can be compared with air quality limits. Impact assessment of air pollution abatement measures can also be carried out.     

Air emission inventories in North America: a critical assessment

Although emission inventories are the foundation of air quality management and have supported substantial improvements in North American air quality, they have a number of shortcomings that can potentially lead to ineffective air quality management strategies. Major reductions in the largest emissions sources have made accurate inventories of previously minor sources much more important to the understanding and improvement of local air quality. Changes in manufacturing processes, industry types, vehicle technologies, and metropolitan infrastructure are occurring at an increasingly rapid pace, emphasizing the importance of inventories that reflect current conditions. New technologies for measuring source emissions and ambient pollutant concentrations, both at the point of emissions and from remote platforms, are providing novel approaches to collecting data for inventory developers. Advances in information technologies are allowing data to be shared more quickly, more easily, and processed and compared in novel ways that can speed the development of emission inventories. Approaches to improving quantitative measures of inventory uncertainty allow air quality management decisions to take into account the uncertainties associated with emissions estimates, providing more accurate projections of how well alternative strategies may work. This paper discusses applications of these technologies and techniques to improve the accuracy, timeliness, and completeness of emission inventories across North America and outlines a series of eight recommendations aimed at inventory developers and air quality management decision-makers to improve emission inventories and enable them to support effective air quality management decisions for the foreseeable future.     

Atmospheric concentrations of saturated and aromatic hydrocarbons around a Greek oil refinery

Petroleum refineries are large industrial installations that are responsible for the emission of several pollutants into the atmosphere. Hydrocarbons are among the most important air pollutants that are emitted by petroleum refineries, since they are involved in almost every refinery process. The ambient air concentrations of many saturated and aromatic hydrocarbons were measured in several sites around an oil refinery, near the city of Corinth in Greece, during 1997. At the same time several meteorological parameters were also recorded. The seasonal, diurnal and spatial variations of the ambient air concentrations of these hydrocarbons were investigated and analyzed. An estimation of the contribution of the refinery to the measured atmospheric levels of hydrocarbons was also performed. The ambient air mixing ratios of the saturated and aromatic hydrocarbons in a large area outside the refinery were generally low, in ppbv range, much lower than the ambient air quality standards or the ambient air concentrations in the two largest urban centers in Greece, Athens and Thessaloniki.     

An automated systems for air sampling with annular denuder systems at a remote site

An automated air sampling system has been designed for use with the annular denuder system (ADS). The automated air sampling system allows for accurate measurements of air volume and day-night sampling while preventing the accumulation of moisture within the ADS caused by condensation or cloud events. The sampling system consists of air flow, monitoring and control subsystems. Calibration of the sampling system against a Hoffer turbine flow meter indicated accurate measurement of air flow volumes. Field testing and preliminary data have shown that the sampling system functions well in a remote mountain forest site, and was relatively unaffected by condensation, fog, or cloud events.     

Simulating sulfur dioxide plume dispersion and subsequent deposition downwind from a stationary point source: a model

Dispersion and subsequent deposition of SO(2) downwind from a stationary point source are affected by several transport processes: buoyancy at the source, advection, and air turbulence en route from the source to the area of impact. In this paper, SO(2) transport processes are simulated by way of Lagrangian air parcel trajectory simulations. In these simulations, the source releases air parcels in puffs. The calculations cover both daytime and night-time conditions and take into account: (i) solar geometry, (ii) diurnal variations of wind speed and air turbulence, (iii) resistance to the transfer of SO(2) from the air to the land, and (iv) flat terrain. Deposition to the forest is determined by calculating the rate of SO(2) flux from individual air parcels to the land according to the parcel's velocity and an assumed air-to-surface SO(2) transfer coefficient. Daily cumulative SO(2) deposition rates are calculated by summing the simulated diffusional fluxes of SO(2) from air to land over each simulated time step. Daily cumulative SO(2) amounts are calculated for downwind distances from 0 to 42 km, for smokestack heights from 30 to 200 m, and for each day of the year according to historical year-round and local weather patterns representative of days with neutral conditions and days with transitions from stable to unstable conditions. Annual per hectare rates of SO(2) deposition are calculated by way of Monte Carlo simulations, according to historical patterns for daily wind, atmospheric stability, and precipitation. These simulations are calibrated for the area surrounding a coal-burning power generator at Grand Lake in south-central New Brunswick, Canada. Calculated concentrations for SO(2) were similar to those obtained with a mobile SO(2) detection unit and a SO(2)-monitoring unit 42 km NE from the emission source. Cumulative SO(2) deposition rates were reasonably similar to those obtained with PbO(2) sulfation plates. A detailed comparison revealed topography was an important factor in modifying actual cumulative SO(2) deposition rates.     

Apparent Photosynthesis as a Measure of Air Pollution Damage

A system has been developed to automatically measure the effects of air pollutants in the ambient air on the rate of CO₂ exchange by intact leaves of citrus trees growing in the field. A miniaturized system utilizing the same nondispersive infrared CO₂ analyzer has been designed to study individually the effects of different concentrations of air pollutants on photosynthesis and respiration by plants.     

Adapting air quality management for a changing climate: Survey of local districts in California

Air quality can be affected by weather and thus is sensitive to a changing climate. Wildfire (influenced by weather), consecutive high temperature summer days, and other extreme events are projected to become more severe and frequent with climate change. These may create challenging conditions for managing air quality despite policy targets to reduce precursor and pollutant emissions. Although extreme events are becoming more intense and interest in climate adaptation is increasing among public health practitioners, little attention in scholarly literature and policy covers climate adaptation for air quality governance. Understanding the management and managers’ perspectives at the local level provides insight about the needs for climate adaptation, including their adaptation status, perspectives, responsibilities, and roles. This study explores local manager perspectives and experiences of managing air quality within a changing climate as one puzzle piece to understand the gap in climate adaptation within the air quality sector. A broader goal is to contribute to the discussion of developing a multi-jurisdictional vision for reducing the impacts of air quality in a changing climate. In 2016 local air quality district managers in California were invited to participate in an online survey of 39 questions focused on extreme event impacts on air quality. The questionnaire focused on present air quality threats and extreme event challenges, adaptation status and strategies, adaptive capacities, perceived barriers to adaptation, and jurisdictional responsibilities and roles. Over 85 percent of the 35 local air districts in California participated in the survey, which represents 80 percent of the state’s population. High awareness and knowledge of climate change among local managers indicates they are ready to adopt and take action on policies that would support climate adaptation, but barriers reported suggests they may need policies and adequate funding to take action and make necessary changes.

Implications: Downscaled global climate models project an increasing severity and frequency of extreme events. In the southwestern United States, these include wildfire, heat events, and dry periods, among others, all of which can place an extra burden on air quality managers and emitters to achieve air quality standards even as they reduce emissions. Despite climate change presenting increasing challenges to meet air quality standards, in the southwestern United States, policy and action to mitigate these impacts have been surprisingly absent. California presents a valuable case study on the topic because of its historic leadership in air quality management for the United States and also because of its initiatives in combating climate change. Yet still we found that adaptation has not been incorporated into air quality management thus far, but local managers seem sufficiently knowledgeable and willing.     

湿污泥在流化床中干燥特性

在鼓泡流化床干燥器内,床料采用0～1 mm的石英砂,以热空气作为干燥介质,对城市污水污泥的流态化干燥特性进行实验研究。通过控制送风温度、流化风量、加料量、污泥粒径等参数,研究在不同工况条件下床温以及干污泥含水率的变化情况。结果表明,随着送风温度的升高,床温升高,干污泥含水率下降,最终趋向于一个稳定值8%。床温随流化风量的增加先是减小而后升高,干污泥的含水率随流化风量的增加先是降低而后增大。当加料量从11 kg/h增加到13kg/h时,干污泥的含水率基本没有变化,当加料量超过13 kg/h时,干污泥的含水率从8.1%开始呈递增趋势。随污泥粒径的增大,床温升高,干污泥含水率也随之升高。     

Local emissions trading in developing countries as a transitional strategy toward international greenhouse gas trading: a Beijing example

As is the case in most developing countries, China relies on command-and-control regulation to control air pollution. While it has instituted a modest air pollution levy system in the past 20 years for emissions in excess of standards, the effect on emission levels has been minimal. This paper focuses on how to use emissions trading as a policy instrument to achieve cost-effective reductions in air pollution in Beijing. Emissions or allowance trading has been widely applied to air pollution control in the USA during the past 25 years. Three of the most recent programmes will be examined, which provide applicable experience for possible SO₂ and NO_x trading in the Beijing region. A trading strategy for Beijing will be proposed by comparing the economic and political institutional differences between the USA and China, which could eventually facilitate acceptance of an international greenhouse gas trading system.     

Quantification and Analysis of Airborne Bacterial Characteristics in a Nursing Care Institution

ABSTRACT

Indoor air quality has become a critical issue because people spend most of their time in the indoor environment. The factors that influence indoor air quality are very important to environmental sanitation and air quality improvement. This study focuses on monitoring air quality, colony counts, and bacteria species of the indoor air of a nursing care institution. The regular colony counts in two different wards range from 55 to 600 cfu m^?3. Regression analysis results indicate that the bacterial colony counts have close correlation with relative humidity or carbon dioxide (CO₂) but not with carbon monoxide (CO) or ozone (O₃). Real-time PCR was used to quantify the bacterial pathogens of nosocomial infection, including Acinetobacter baumannii, Citrobacter freundii, Escherichia coli, Klebsiella pneumoniae, and methicillin-sensitive Staphylococcus aureus. The most abundant bacteria species in the air of the nursing care institution is E. coli.

IMPLICATIONS Indoor temperature, humidity, ventilation, accumulation of biological pollutants, and potential infection problems will seriously affect the indoor environments. Studying these factors is important to indoor environmental sanitation and air quality improvements. Results of using real-time PCR to evaluate the bacterial pathogens of nosocomial infection for a nursing care institution in Taiwan reveal that the main bacteria species existing in the indoor air is E. coli.     

Regional air pollution at a turning point

The control of transboundary air pollution in Europe has been successful. Emissions of many key pollutants are decreasing and there are signs of improvements in damaged ecosystems. The strategies under development within the CAFE programme under the European Commission and the Convention on Long-range Transboundary Air Pollution (CLRTAP), aim to take regional air pollution control a large step further, in particular with respect to small particles. In this paper we highlight the new strategies but look primarily at socioeconomic trends and climate change feedbacks that may have a significant influence on the outcome of the strategies and which so far have not been considered. In particular, we point out the influence on air quality of increased summer temperatures in Europe and of increasing emissions including international shipping, outside of Europe. Taken together the further emissions reductions in Europe and the increasing background pollution, slowly cause a greying of the Northern Hemisphere troposphere rather than the traditional picture of dominant emissions in Europe and North America ('black') with much lower emission intensities elsewhere ('white'). A hemispheric approach to further combat air pollution will become necessary in Europe and elsewhere.