Air Pollution and Human Health: Perspectives for the '90s and Beyond

This paper considers the health effects of air pollution from three perspectives: historical, statistical, and public policy, and also as depicted by the recent epidemiology, primarily mortality studies. The historical perspectives establish the reality of population-based health effects, and they provide data with which to evaluate more recent evidence. Statistical perspectives imply that, while there is strong evidence that associations between air quality and health persist, many details of these relationships remain obscure, especially as to the existence of concentration thresholds that might define safe exposure levels. Additional major questions include the effects of uncertainties in actual pollution exposures, the degree of prematurity of "excess" deaths, and whether the development of new cases of chronic disease is associated with air pollution. Public policy issues center around interpreting the new epidemiological studies in the light of these uncertainties and the analysis and management of the concomitant health risks.     

空气污染对重污染公司股票价格的影响:基于政策干预视角的经济价值研究

随着经济发展和产业结构调整，社会公众和政府部门对空气污染问题的原因和治理给予了更多关注。空气重污染公司聚焦度陡增，在经营业绩、发展前景和股市表现方面受到不同程度的冲击。本文利用2014—2019年全国地级市层面空气重污染公司的日度非平衡面板数据，研究政策干预视角下空气污染对股票交易的影响及其经济价值。相较人体弹性感知能力，以空气质量等级变化为触发条件的地方政府防治措施能够更精准地对空气污染做出反应，进而通过公司基本面和投资者情绪渠道影响股市交易。实证结果显示，空气质量等级恶化会对空气重污染公司的股价产生非持续性负面影响，且股价的短期下跌伴随换手率上升特点。经济意义检验表明，空气污染与股价短期关系的发现能够指导投资实践以获取经济增益，而空气质量指数具有改进股价预测的潜力。本文的研究对理解政策干预视角下空气污染对股票市场的影响、股价预测和投资组合均具有十分重要的理论和实践意义。     

Exposure-Response Functions for Health Effects of Air Pollutants Based on Epidemiological Findings

Quantitative knowledge about health damage due to air pollution is an important element in analyses of cost-effective abatement strategies, and is also essential for setting Air Quality Standards. Epidemiological studies, in spite of the numerous problems connected to them, provide a reasonable basis for exposure-response functions in this context. On the basis of a literature review, exposure-response functions that relate ambient air pollutant concentrations to the frequency of various health effects are recommended in this paper. The following end-points were examined: Acute and chronic respiratory symptoms in children and adults, crude mortality, and lung cancer incidence. The effects are attributed to one indicator component, which in most cases is particles. A calculation procedure is suggested which makes it possible to estimate excess annual symptom-days for short-term effects using the annual average concentration.     

A New Air Quality Perception Scale for Global Assessment of Air Pollution Health Effects

Despite improvements in air quality in developed countries, air pollution remains a major public health issue. To fully assess the health impact, we must consider that air pollution exposure has both physical and psychological effects; this latter dimension, less documented, is more difficult to measure and subjective indicators constitute an appropriate alternative. In this context, this work presents the methodological development of a new scale to measure the perception of air quality, useful as an exposure or risk appraisal metric in public health contexts. On the basis of the responses from 2,522 subjects in eight French cities, psychometric methods are used to construct the scale from 22 items that assess risk perception (anxiety about health and quality of life) and the extent to which air pollution is a nuisance (sensorial perception and symptoms). The scale is robust, reproducible, and discriminates between subpopulations more susceptible to poor air pollution perception. The individual risk factors of poor air pollution perception are coherent with those findings in the risk perception literature. Perception of air pollution by the general public is a key issue in the development of comprehensive risk assessment studies as well as in air pollution risk management and policy. This study offers a useful new tool to measure such efforts and to help set priorities for air quality improvements in combination with air quality measurements.     

Technical Uncertainty in Quantitative Policy Analysis — A Sulfur Air Pollution Example

Expert judgments expressed as subjective probability distributions provide an appropriate means of incorporating technical uncertainty in some quantitative policy studies. Judgments and distributions obtained from several experts allow one to explore the extent to which the conclusions reached in such a study depend on which expert one talks to. For the case of sulfur air pollution from coal-fired power plants, estimates of sulfur mass balance as a function of plume flight time are shown to vary little across the range of opinions of leading atmospheric scientists while estimates of possible health impacts are shown to vary widely across the range of opinions of leading scientists in air pollution health effects.     

Estimating the Risks of Smoking, Air Pollution, and Passive Smoke on Acute Respiratory Conditions

Five years of the annual Health Interview Survey, conducted by the National Center for Health Statistics, are used to estimate the effects of air pollution, smoking, and environmental tobacco smoke on respiratory restrictions in activity for adults, and bed disability for children. After adjusting for several socioeconomic factors, the multiple regression estimates indicate that an independent and statistically significant association exists between these three forms of air pollution and respiratory morbidity. The comparative risks of these exposures are computed and the plausibility of the relative risks is examined by comparing the equivalent doses with actual measurements of exposure taken in the homes of smokers. The results indicate that: (1) smokers will have a 55-75% excess in days with respiratory conditions severe enough to cause reductions in normal activity; (2) a 1 microgram increase in fine particulate matter air pollution is associated with a 3% excess in acute respiratory disease; and (3) a pack-a-day smoker will increase respiratory restricted days for a nonsmoking spouse by 20% and increase the number of bed disability days for young children living in the household by 20%. The results also indicate that the estimates of the effects of secondhand smoking on children are improved when the mother's work status is known and incorporated into the exposure estimate.     

大气污染协同治理能促进污染物减排吗?--基于城市的三重差分研究

大气污染具有流动性,跨区域特征明显,协同治理至关重要。基于2010-2015年275个城市的面板数据,运用三重差分法(DDD)研究了大气污染协同治理对污染物减排的影响。从全样本分析结果来看,大气污染协同治理降低了工业二氧化硫排放量和工业烟(粉)尘排放量,而此结果并没有通过显著性检验。从子样本分析结果来看,大气污染协同治理显著降低了工业二氧化硫排放量,但对工业烟(粉)尘排放量没有产生显著影响。城市在促进不同污染物减排时存在差异,减排难度较低的污染物往往被优先完成。从时间效应来看,大气污染协同治理对污染物减排的影响存在时滞性,而且这种时滞性在不同污染物减排之间存在差异。     

Experience with urban air pollution in Paterson, New Jersey and implications for air pollution communication

Communication about air pollution can help reduce health risks, but a scattered, largely qualitative literature on air pollution beliefs, attitudes, and behaviors raises questions about its effectiveness. A telephone survey of Paterson, New Jersey (USA) residents tested four hypotheses aimed toward integrating these findings. Self-reported sheltering indoors during high pollution, the recommended strategy, was predicted by perceived air quality and self-reported "sensitivity" to air pollution. Nearly a quarter of the sample reported mandatory outdoor activity (e.g., work) that might increase their exposures, but this factor did not significantly affect self-reported sheltering. Perceptions of air quality did not correlate strongly with official monitoring data (U.S. Air Quality Index (AQI)); even people who regularly sought AQI data relied upon sensory cues to high pollution, and secondarily upon health cues. Use of sensory and health cues, definitions of what makes someone sensitive to air pollution, and (less strongly) definitions of vulnerability to air pollution varied widely. The minority aware of the AQI were more likely to seek it if they had illnesses or saw themselves in the targeted AQI audience, yet less likely if they believed themselves sensitive to pollution. However, their sense of the AQI's match to their own experience was driven by whether they used sensory (yes) or health (no) cues, not by illness status. Some urban residents might not have access to AQI data, but this barrier seems outweighed by need to bridge interpretive gaps over definitions of air pollution, sensory perception, vulnerability, and health consequences.     

A STOCHASTIC MODEL FOR ANALYSIS OF VARIATIONS IN AIR POLLUTION LEVELS

Examination of environmental data seems to suggest that variations in air pollution levels from one point in time to another tend to follow some form of observable pattern. In this article, the authors explore an approach to observing, describing and analyzing these variations. They develop a model which is essentially a Markov framework and use it to suggest a number of interesting questions and to facilitate their solution. In this demonstration, the focus is on a single component of air pollution, suspended particulate matter. For implementation, a model would need to incorporate other elements of the pollution mix. As the composition of air pollution differs from one air shed to another, so will the parameters of the model.     

城市机动车限行对PM2.5的影响与效果检验

为缓解城市道路拥堵与交通污染问题,全国多地陆续实施机动车限行政策,但针对不同城市不同限行政策对大气污染的影响却鲜有文献研究。根据政策特征,本文将限行政策分为一般限行和特殊限行两类。基于双重差分模型,采用2001-2017年我国各省会城市及直辖市的面板数据,本文分别研究了不同类型的限行政策对城市PM_2.5污染的改善作用。研究发现：首先,机动车PM_2.5排放已经成为了城市PM_2.5排放的主要来源之一,机动车限行措施也越来越多地被运用到治理城市空气污染的过程中;第二,一般限行政策和特殊限行政策均不同程度地缓解了大气污染,但相对而言,特殊限行政策的减排效果更明显;第三,限行政策的力度,如限行区域的相对大小和限制机动车的相对数量均能影响政策效果,一般来说,限行区域越大,限行的车辆越多,减排效果越显著;第四,在剔除特殊样本"北京"和"限购"政策的影响后,限行政策依然有效。本文从机动车PM_2.5排放的角度实证检验了限行政策对大气污染的影响和效果,为政府进一步制定更高效合理的道路交通污染防治措施提供了参考依据。     

Health Risks and Air Pollution — Error Analysis for a Cross-Sectional Mortality Study

An attempt is made to analyze in quantitative terms the uncertainties in multiple regression estimates of the effects of air pollution on death rates. A range of factors--statistical fluctuations in numbers of deaths, differences in local age distribution, differences in smoking habits, errors in estimated pollution levels, migration, and variability of the characterization of socioeconomic effects--are assessed as potential sources of error. Both the precision and the robustness of the regression calculation are shown to be poor. Examples and illustrative calculations are given based on a study of U. K. death rates around the 1971 Census.     

大气污染府际间合作治理联盟的达成与稳定——基于演化博弈分析

地方政府的大气污染治理模式主要有属地治理和合作治理模式,合作治理逐渐成为当前大气污染治理的共识。从演化博弈的视角,分析地方政府在大气污染治理中的行为演化路径与稳定策略,探究地方政府间达成并巩固合作治理联盟的因素。比较有中央约束和无中央政府约束下地方政府属地治理和合作治理四种演化博弈结果表明：在属地治理背景下,无论中央政府是否对地方政府进行约束,地方政府均倾向于“搭便车”行为,而中央政府对地方政府的约束在属地治理中面临失灵;在合作治理场景中,地方政府的稳定策略均向达成合作治理或均不治理的方向演进,但在中央政府约束下,地方政府的稳定策略能快速有效得向合作治理的方向演进。为实现大气污染的有效治理,地方政府间必须形成有效的合作治理联盟,合作收益是达成大气污染合作治理联盟的必要条件,而合作成本与中央政府约束的程度决定了合作治理联盟的稳定性。     

The Effects of Urban Form on Ambient Air Pollution and Public Health Risk: A Case Study in Raleigh,North Carolina

Since motor vehicles are a major air pollution source, urban designs that decrease private automobile use could improve air quality and decrease air pollution health risks. Yet, the relationships among urban form, air quality, and health are complex and not fully understood. To explore these relationships, we model the effects of three alternative development scenarios on annual average fine particulate matter (PM_2.5) concentrations in ambient air and associated health risks from PM_2.5 exposure in North Carolina's Raleigh‐Durham‐Chapel Hill area. We integrate transportation demand, land‐use regression, and health risk assessment models to predict air quality and health impacts for three development scenarios: current conditions, compact development, and sprawling development. Compact development slightly decreases (?0.2%) point estimates of regional annual average PM_2.5 concentrations, while sprawling development slightly increases (+1%) concentrations. However, point estimates of health impacts are in opposite directions: compact development increases (+39%) and sprawling development decreases (?33%) PM_2.5‐attributable mortality. Furthermore, compactness increases local variation in PM_2.5 concentrations and increases the severity of local air pollution hotspots. Hence, this research suggests that while compact development may improve air quality from a regional perspective, it may also increase the concentration of PM_2.5 in local hotspots and increase population exposure to PM_2.5. Health effects may be magnified if compact neighborhoods and PM_2.5 hotspots are spatially co‐located. We conclude that compactness alone is an insufficient means of reducing the public health impacts of transportation emissions in automobile‐dependent regions. Rather, additional measures are needed to decrease automobile dependence and the health risks of transportation emissions.     

Approximations for Estimating Change in Life Expectancy Attributable to Air Pollution in Relation to Multiple Causes of Death Using a Cause Modified Life Table

There is considerable debate as to the most appropriate metric for characterizing the mortality impacts of air pollution. Life expectancy has been advocated as an informative measure. Although the life‐table calculus is relatively straightforward, it becomes increasingly cumbersome when repeated over large numbers of geographic areas and for multiple causes of death. Two simplifying assumptions were evaluated: linearity of the relation between excess rate ratio and change in life expectancy, and additivity of cause‐specific life‐table calculations. We employed excess rate ratios linking PM_2.5 and mortality from cerebrovascular disease, chronic obstructive pulmonary disease, ischemic heart disease, and lung cancer derived from a meta‐analysis of worldwide cohort studies. As a sensitivity analysis, we employed an integrated exposure response function based on the observed risk of PM_2.5 over a wide range of concentrations from ambient exposure, indoor exposure, second‐hand smoke, and personal smoking. Impacts were estimated in relation to a change in PM_2.5 from 19.5 μg/m³ estimated for Toronto to an estimated natural background concentration of 1.8 μg/m³. Estimated changes in life expectancy varied linearly with excess rate ratios, but at higher values the relationship was more accurately represented as a nonlinear function. Changes in life expectancy attributed to specific causes of death were additive with maximum error of 10%. Results were sensitive to assumptions about the air pollution concentration below which effects on mortality were not quantified. We have demonstrated valid approximations comprising expression of change in life expectancy as a function of excess mortality and summation across multiple causes of death.     

Air Pollution and Mortality: Quantification and Valuation of Years of Life Lost

To analyze the loss of life expectancy (LLE) due to air pollution and the associated social cost, a dynamic model was developed that took into account the decrease of risk after the termination of an exposure to pollution. A key parameter was the time constant for the decrease of risk, for which estimates from studies of smoking were used. A sensitivity analysis showed that the precise value of the time constant(s) was not critical for the resulting LLE. An interesting aspect of the model was that the relation between population total LLE and PM2.5 concentration was numerically almost indistinguishable from a straight line, even though the functional dependence was nonlinear. This essentially linear behavior implies that the detailed history of a change in concentration does not matter, except for the effects of discounting. This model was used to correct the data of the largest study of chronic mortality for variations in past exposure, performed by Pope et al. in 1995; the correction factor was shown to depend on assumptions about the relative toxicity of the components of PM2.5. In the European Union, an increment of 1 microg/m3 of PM2.5 for 1 year implies an average LLE of 0.22 days per person. With regard to the social cost of an air pollution pulse, it was found that for typical discount rates (3% to 8% real) the cost was reduced by a factor of about 0.4 to 0.6 relative to the case with zero discount rate, if the value of a life year was taken as given; if the value of a life year was calculated from the "value of statistical life" by assuming the latter as a series of discounted annual values, the cost varied by at most +/-20% relative to the case with zero discount rate. To assess the uncertainties, this study also examined how the LLE depended on the demographics (mortality and age pyramid) of a population, and how it would change if the relative risk varied with age, in the manner suggested by smoking studies. These points were found to have a relatively small effect (compared to the epidemiological uncertainties) on the calculated LLE.     

The Risk Screening for Indoor Air Pollution Chemicals in Japan

In recent years, public health problems caused by indoor air pollution have been drawing strong public concern in Japan. After conducting extensive exposure assessment, governmental agencies have taken effective measures to solve the problem; for instance, "Guidelines for indoor air quality (IAQ)" of 13 chemicals, for example, formaldehyde, toluene, and xylene, has been established. Thousands of chemicals have been identified in the indoor environment. Priority rating of those chemicals, however, was not based on the health risk level. We developed a risk-screening scheme for indoor air pollution chemicals and analyzed the current status of the risk levels of those chemicals in Japan. We researched scientific knowledge of health hazards and exposure surveys of indoor air pollution chemicals in Japan, and classified those chemicals based on the health risk level estimated from the scheme. The risk levels of 93 chemicals were characterized and six chemicals (formaldehyde, acrolein, 1,4-dichlorobenzene, benzene, tetrachloroethylene, and benzo(a)pyrene) were classified in the highest risk category.     

Can Property Values Capture Changes in Environmental Health Risks? Evidence from a Stated Preference Study in Italy and the United Kingdom

Hedonic models are a common nonmarket valuation technique, but, in practice, results can be affected by omitted variables and whether homebuyers respond to the assumed environmental measure. We undertake an alternative stated preference approach that circumvents these issues. We examine how homeowners in the United Kingdom and Italy value mortality risk reductions by asking them to choose among hypothetical variants of their home that differ in terms of mortality risks from air pollution and price. We find that Italian homeowners hold a value of a statistical life (VSL) of €6.4 million, but U.K. homeowners hold a much lower VSL (€2.1 million). This may be because respondents in the United Kingdom do not perceive air pollution where they live to be as threatening, and actually live in cities with relatively low air pollution. Italian homeowners value a reduction in the risk of dying from cancer more than from other causes, but U.K. respondents do not hold such a premium. Lastly, respondents who face higher baseline risks, due to greater air pollution where they live, hold a higher VSL, particularly in the United Kingdom. In both countries, the VSL is twice as large among individuals who perceive air pollution where they live as high.     

AIR QUALITY CONTROL MODEL COMBINING DATA ON MORBIDITY AND POLLUTION ABATEMENT*

A pollution damage function is developed, using data from a study on the sensitivity of morbidity to ambient air concentrations of individual pollutants. This function is used in a model which incorporates the costs and technology for pollution abatement in the St. Louis Airshed. A set of air quality standards is determined which minimizes morbidity subject to a given control budget constraint. The results indicate that there should be a greater reduction of the pollutants associated with stationary sources than of those characteristic of the automobile.