Integrated simulation of land use,transportation and air quality: Policy tests for the San Francisco region

This paper describes a series of tests carried out with a comprehensive transportation, land use and air quality simulation system, which has been designed for planning application at the metropolitan or regional scale, within the framework of the U.S. Government's Clean Air legislation. The urban location portion of the system was developed at the University of Pennsylvania under the direction of S. H. Putman. The air quality sections incorporate models formulated in earlier studies. The system was tested with data from the San Francisco Bay area, for the period 1975–1980. The test policies included changes in regional transportation costs and population totals; local interventions in the transportation network; and controls on pollutant emissions from mobile and stationary sources. To assess net impacts, the outcomes predicted for each policy were compared with the outcomes predicted in a “benchmark”, or base run of the system. The tests showed that the system is sensitive to a broad range of air quality policies, and that it is capable of predicting important air quality consequences of transportation and land use policies. Some further development will be needed before the system can be used in practical planning situations, but there is little doubt as to the soundness of its central theoretical constructs and logical structure.     

Indoor air quality and minimum ventilation rate

In a 30-m³ test chamber the air pollutants caused by man were measured. Variables were the number of persons and the rate of air change. During 2-h test sessions the temperature, relative humidity, carbon dioxide, and intensity of odors were measured. The relationship between the perceived odor intensities and the concentrations of carbon dioxide-independent of the number of persons and the air change rate—was observed. At air change rates of 12–15 m³/person/h, the carbon dioxide concentration was not higher than 0.15% and the odor intensity was evaluated only as a “slight annoyance.” Higher ventilation rates are necessary if smoking and increased physical activities are done in the rooms.     

Methods for control of indoor air quality

This report presents results of a review of available methods for control of environmental hazards applied to indoor air pollutants. Indoor air pollution originates from transport of ambient outdoor air contaminants into occupied spaces by natural infiltration ventilation, or by mechanical ventilation using outdoor makeup air, plus contributions from indoor emission sources. When air exchange with the external ambient environment is reduced to conserve energy, contributions from indoor emission sources may dominate indoor air pollutant levels. This paper identifies alternative methods available to control indoor air pollutant exposures. The performance characteristics of ventilation systems and of air cleaning devices used in mixed modes for ventilation of occupied spaces are described. Models for predicting effectiveness of several alternative modes are reviewed, with field trial validation results cited where available. Results of previous confined-space studies are briefly reviewed as points of departure for consideration of necessary air quality, ventilation, and air cleaning. Understanding of indoor air contaminant generation and controls is aided by examination of earlier studies of indoor air quality, using modern perspectives on occupational environmental health and hygiene.     

Olfactory and chemical characterization of indoor air. Towards a psychophysical model for air quality

The relationship between the odor strength of total air samples and the odor strengths of the constituents was investigated in three field experiments in an office building and a new preschool. The odor strength was scaled by magnitude estimation according to a master scale principle which results in comparable values for the total and the constituent odors. Between 60 and 120 chemical components were detected by GC/FID in the indoor air samples (N = 66). Most (81%) of the detected components in an air sample were odorous, even though most of them were of the low concentrations. By a method of pattern analysis, chemical as well as odor patterns of indoor air were found to be characteristics of different buildings. From the odor patterns (POG), the “odor print” of the outdoor air associated with the buildings was also recognized in the indoor air. Thus, the “odor print” of an air sample is different from its “chemical print”. A model was found that predicts the overall odor strength of an air sample from the number of FID-detected components most frequently reported to have a strong odor.     

Studies on indoor air quality in Egypt

Indoor air quality was examined for some gaseous pollutants and particulate matters. In a public library, the indoor/outdoor ratio of gaseous pollutants were found to be dependent on their reactivity, also on the outdoor concentrations and weather conditions. This ratio was 0.6 for SO₂,and 1.3 for CO. The indoor/outdoor ratio of carbon monoxide was found to increase at the higher floors of the same building. Concentrations of indoor particulates was found to be influenced by the outdoor concentrations and the particle size. Analysis indicated that indoor suspended dust contained a significant high concentration of lead as compared with outdoor values. Indoor sources were found to pollute the premises of fossil-fuel equipped homes, thus having carbon monoxide concentrations more than the recognized threshold limit value for industry.     

Comparing urban air quality in Europe in real time a review of existing air quality indices and the proposal of a common alternative

The EU directives on air quality force member states to inform the public on the status of the ambient air quality. The Internet is commonly used for this purpose and often air quality is being presented as an index ranging from good to bad. A review of existing websites and air quality indices shows that the way air quality is interpreted differs considerably. The paper presents a new air quality index. The index is part of a project to develop a website dedicated to comparing air quality in European cities. The common air quality index (CAQI) is not aimed at replacing existing local indices. The CAQI is a set of two indices: one for roadside monitoring sites and one for average city background conditions. Differentiating between roadside and general city conditions is a first step in assuring consistence in the parameters that are being compared.     

The dichotomy of relative humidity on indoor air quality

Dry and irritated mucous membranes of the eyes and airways are common symptoms reported in office-like environments. Earlier studies suggested that indoor pollutants were responsible. We have re-evaluated, by review of the literature, how low relative humidity (RH) may influence the immediately perceived indoor air quality (IAQ), including odour, and cause irritation symptoms (i.e. longer-term perceived IAQ). "Relative humidity" were searched in major databases, and combined with: air quality, cabin air, dry eyes, formaldehyde, inflammation, mucous membranes, offices, ozone, pungency, sensory irritation, particles, precorneal tear film, sick building syndrome, stuffy air, and VOCs. The impact of RH on the immediately and longer-term perceived IAQ by VOCs, ozone, and particles is complex, because both the thermodynamic condition and the emission characteristics of building materials are influenced. Epidemiological, clinical, and human exposure studies indicate that low RH plays a role in the increase of reporting eye irritation symptoms and alteration of the precorneal tear film. These effects may be exacerbated during visual display unit work. The recommendation that IAQ should be "dry and cool" may be useful for evaluation of the immediately perceived IAQ in material emission testing, but should be considered cautiously about the development of irritation symptoms in eyes and upper airways during a workday. Studies indicate that RH about 40% is better for the eyes and upper airways than levels below 30%. The optimal RH may differ for the eyes and the airways regarding desiccation of the mucous membranes.     

Current status of models in determining optimum chlorination practices

Interest in mathematical models for predicting the fate of chlorine in natural waters arose in the 1970's, and evolution of these models has proceeded rapidly. The crudest of the models incorporate empirical estimates of chemical reactions in a single term to predict generic chlorine products such as total residual chlorine or free residual chlorine. A second order of model complexity includes use of multifactor predictor variables to approximate losses of chlorine via chemical reaction, but predictions are still couched in terms of generic chlorine products. The most sophisticated of the current models are based on specific chemical reactions and predict the identity and quantity of some (but not all) of the products resulting from chlorination of natural waters. None of these models have been sufficiently verified, but each has some potential value for assessment of environmental effects of chlorinated discharges. Evaluation of the strengths and weaknesses of existing models is presented to stimulate further model development and to direct the focus of chemical studies toward collection of data most critical for derivation of input parameters.     

The effects of woodburning on the indoor residential air quality

Data from suburban residences in the Boston metropolitan area reveal a potential adverse impact on indoor air quality from woodburning in woodstoves and fireplaces. Ambient pollutant concentrations at each residence were compared to corresponding pollutant levels indoors at three locations (kitchen, bedroom, and activity room). Individual gaseous pollutant samples were averaged on an hourly basis while 24-h integrated samples of particulate matter were obtained. Ten gaseous pollutants were sampled along with total suspended particulates (TSP). Chemical analyses further determined ten components of TSP including trace metals, benzo-a-pyrene(B)aP, respirable suspended particulates (RSP), and water soluble sulfates and nitrates. Monitoring lasted two weeks at each residence and was conducted under occupied, real-life, conditions. Observed, elevated indoor concentrations of TSP, RSP, and BaP are attributed to woodburning. Data indicate that average indoor TSP concentrations during woodburning periods were about three times corresponding levels during nonwoodburning periods. The primary 24-h national ambient air quality standard (NAAQS) for TSP was exceeded once indoors during fireplace use, and the secondary, 24-h TSP NAAQS, was also exceeded indoors by RSP concentrations. Indoor BaP concentrations during woodstove use averaged five times more than during nonwoodburning periods. At this stage, results are only indicative, but the potential impact from elevated indoor concentrations of TSP, RSP, and BaP, attributed to woodburning, may have long-term health implications.     

Local air quality management as a risk management process: assessing, managing and remediating the risk of exceeding an air quality objective in Great Britain

Air quality is managed in Great Britain via an effects-based, risk management process designed to provide a dynamic solution to public health issues associated with elevated concentrations of seven specified air pollutants. This paper is concerned with an examination and evaluation of the process of Local Air Quality Management (LAQM) in Great Britain from the late 1980s to date as a risk management process. The statutory basis of LAQM process is provided by the Environment Act 1995. The Act provides a framework in which national and local actions are required to identify and remediate areas of poor air quality. Within this framework, the implementation of the process at national and local levels is considered, leading to an identification and assessment of risks in the formulation and implementation of air quality management policy and practice. Local Authorities began the process of Review and Assessment in 1999 and the first round of the process concluded in 2001. Following this, some 129 Local Authorities declared one or more Air Quality Management Areas (AQMAs). The Review and Assessment elements of the framework were subjected to an evaluation in 2001 and the essential elements of it were confirmed as fit for purpose. The evaluation led to a confirmation of the process of LAQM but also a simplification based on the experience of Round 1. Now, a two step process is required comprising of an Updating and Screening Assessment and, where a risk of exceeding an Air Quality Objective (AQO) is identified, a Detailed Assessment follows. The Government has identified a time scale for Review and Assessment through to 2010 and also introduced the requirement of a regular Progress Report in order that a Local Authority is able to address routine matters of air quality management. The risks inherent in epidemiological or scientific uncertainty are factored into the LAQM process at an early stage of the process and, by identifying the risks and subjecting them to regular review, the process provides a 'level playing field' across spatial and temporal scales. Whilst the process of LAQM described in this paper has been developed for Great Britain, the generic elements of the process are applicable to other countries challenged by air pollution problems which require both national and local action to resolve them.     

Procedures for estimation of modelling uncertainty in air quality assessment

The main objectives of this work focus, firstly, on a review of the current existent methodologies to estimate air quality modelling uncertainty, and, secondly, in the preparation of guidelines for modelling uncertainty estimation, which can be used by local and regional authorities responsible for air quality management. From the application exercise, it was concluded that it is possible to define a subset of statistical parameters able to reproduce the general uncertainties estimation. Concerning the quality indicators defined by EU directives, the results show that the legislated uncertainty estimation measures are ambiguous and inadequate in several aspects, mainly in what concerns the error measures for hourly and daily indicators based on the highest observed concentration. A relative error at the percentile correspondent to the allowed number of exceedances of the limit value was suggested and tested, showing that is a more robust and appropriate parameter for model performance evaluation.     

基于选择实验方法的北京市空气质量价值评估

科学地评估空气质量的经济价值是政府制定空气污染治理政策的必要前提。近年来选择实验方法逐渐兴起,并被研究者广泛应用于环境价值评估。与其他陈述偏好方法相比,选择实验的一个优势是其具有更高的外部效度。选择实验方法在国内的应用研究尚处在起步阶段。本研究分别在2015年和2016年对北京市居民开展了两次基于选择实验方法的网络调查,在调查数据的基础上采用随机参数Logit和广义多元Logit模型分析了北京市居民对空气质量的偏好,并据此估算了空气质量价值。根据2015年样本的估算结果,雾霾天气(PM_(2.5)超标)和沙尘天气(PM_(10)超标)对北京市居民的平均边际价值分别为6.32元/d和2.69元/d;根据2016年样本的估算结果,两个价值分别为7.72元/d和2.81元/d。上述估算结果在两次调查样本中基本稳定,而且,在多种模型设定下都具有较强的稳健性,与近年来的同类研究结果基本一致。以2016年样本的估算结果为基础,2015年北京市雾霾天气和沙尘天气引起的价值损失分别为239.61亿元和45.13亿元,占北京市当年GDP总量的1.04%和0.20%。进一步研究发现,北京市2015年和2016年空气质量改善的价值均低于北京市政府同年用于治理空气污染投入的财政资金总量,说明资金使用效率有待进一步提高;此外,虽然空气质量对高收入居民具有更高的价值,但是,以收入水平为指标设计的累进税率并不比固定税率更优。     

Comparative overview of indoor air quality in Antwerp, Belgium

This comprehensive study, a first in Belgium, aimed at characterizing the residential and school indoor air quality of subgroups that took part in the European Community Respiratory Health Survey and the International Study of Asthma and Allergy in Childhood [Masoli M, Fabian D, Holt S, Beasley R. Global Burden of Asthma, Medical Research Institute of New Zealand, University of Southampton; 2004.] questionnaire-based asthma and related illnesses studies. The principal aim was to perform a base-line study to assess the indoor air quality in Antwerp in terms of various gaseous and particulate pollutants. Secondly, it aimed to establish correlations between these pollutants investigated, the pollutant levels in the indoor and outdoor micro-environments, findings of the previous questionnaire-based studies and an epidemiological study which ran in conjunction with this study. Lastly, these results were compared and evaluated with current indoor and ambient guidelines in various countries This paper presents selected results on PM1, PM2.5 and PM10 mass concentrations and elemental C estimates as black smoke, as well as gaseous NO(2), SO(2), O(3) and BTEX concentrations of 18 residences and 27 schools. These are related to current guidelines of Flanders, Germany, Norway, China and Canada and evaluated with reference to selected similar studies. It was found that indoor sources such as tobacco smoking and carpets, the latter causing re-suspension of dust, are responsible for elevated indoor respirable particulate matter and place school children and residents at risk. Both PM2.5 and PM10 equalled or exceeded the current guidelines adopted by Flanders, noting that 12-h and 24-h PM2.5 were compared with an annual limit value. Indoor and ambient NO(2) concentrations in the school campaign were higher than the annual EU ambient norm. The other studied pollutant levels were below the current guidelines.     

Future directions in air quality research: economic issues

Our challenge was to address future directions in air quality research that involve economic issues. The paper outlines the role of economics in the evaluation of air pollution impacts on environmental systems and describes existing research. We identify studies that address economic effects in the agricultural sector, in the commercial forest sector, and in unmanaged natural systems. Effects related to ozone exposure are highlighted. The summary of available research is followed by a discussion of research recommendations. Several short-term recommendations are identified that can augment some of the new research being considered by scientists. A more ambitious, long-term research project is outlined for valuing air pollution impacts in unmanaged natural environments. Specifically, the paper describes possible advantages of an 'integrated assessment' framework that more formally brings together the complex relationships that exist in both ecological and economic systems. A final section contains thoughts on the importance of education (i.e., information transfer) in the research process, especially in relation to policy. It is further noted that education should be inclusive of all members of the research team, throughout all stages of the research process.     

Guidelines for Nordic building regulations regarding indoor air quality

A subcommittee of the Nordic Committee for Building Codes has released guidelines for building regulations regarding indoor air quality, especially concerning ventilation. The main features of the guidelines, such as acceptable outdoor air quality for ventilation and minimum outdoor air flows for dwellings and offices, are presented and discussed. Mechanical ventilation is, in principle, required in all buildings including dwellings, due to the requirement of a minimum outdoor air change of 0.5 h⁻¹ and the normal highly airtight nature of new buildings. The guidelines are a basis for designing energy-efficient buildings while maintaining an indoor air quality which provides acceptable comfort and does not impair health.     

The relationships of sprawl and ozone air quality in United States' metropolitan areas

This article reports the results of an examination of the relationships between degree of sprawl and improvements in ozone air quality for 52 metropolitan areas in the US. It also examines state political alignment and environmental resources with regard to these two primary objects of investigation. Evidence of a relationship between sprawl and air quality improvement was identified, but the evidence is ambiguous. More research appears warranted to explore the sprawl–air quality improvement relationship. Electronic Publication     

Evaluation of health benefits for improving indoor air quality in workplace

In contrast to a majority of reported damage-cost literature being focused on outdoor pollution, this paper describes the development of a protocol that links population exposure data with reported epidemiological concentration-response coefficients. A change in indoor particulate level is expressed as a change in total exposure levels, which is then linked with a corresponding change in ambient particulate concentrations before evaluating the associated health benefits. In this study, the development of protocol is illustrated by using a typical office building environment and daily time activity patterns of office occupants in Hong Kong. Our results indicate that some benefit gains for the owners-employers and the society would be anticipated if certain filter set configurations had been adopted. However, the amount of benefit gains for the owners-employers is shown to be increased with the average salary level of employees and the duration of their stay in offices.     

Emissions trading: An improved technique for air quality management

The emissions trading program was one of the first major regulatory reform efforts at the U.S. Environmental Protection Agency under the Reagan Administration. This program is a set of guidelines for the states to develop federally approved transactions in discharge permits, called an Emission Reduction Credit. The rules governing emissions trading apply within a total ambient constraint or “pollution budget.” This paper provides a discussion of the emissions trading program as an improved technique for air quality management. The paper begins with a discussion of the concept of emissions trading and how the EPA emissions trading program fits into the U.S. Clean Air Act. It is then argued that emissions trading provides a more cost-effective set of implementation incentives in comparison to a “command and control” regulatory system. A number of important attributes of the emissions trading program are discussed, and estimates of cost reductions are provided. The current status of the implementation of the emissions trading program is discussed. The paper concludes with a discussion of several legal, technical, and administrative obstacles to obtaining the efficiencies of emissions trading.     

Indoor air quality modeling: Compartmental approach with reactive chemistry

Data on indoor/outdoor pollutant and tracer concentrations were collected during different periods in 1981 at a residence in Newton, MA. Special studies within the kitchen were conducted to determine the vertical and horizontal variability of pollutant and tracer gas concentrations. A reactive chemistry model incorporating simplified NO_x chemistry was developed to simulate pollutant concentrations indoors. Multicompartmental mathematical modeling tools were also developed and tested to estimate efficiently the effective, emission, ventilation, and removal rates, as well as the intercompartmental pollutant exchange coefficients. Model studies utilizing two- and three-compartment systems and tracer measurements proved that the dynamics of pollutant mixing inside a kitchen is not only complex but may be quite important in controlling spatial and temporal variability of reactive species. Further monitoring and modeling studies to investigate the critical aspects of the short-term dynamics of the reactive pollutants inside homes with gas cooking stoves are recommended.