Glass Fibers and Their Use as Filter Media

Typical air quality effect levels of photochemical oxidants on specific plant substrates are illustrated. These include ambient oxidant exposure data measured as “total oxidant” as well as laboratory exposures to individual pure oxidants, ozone, or PAN compounds, since these oxidants are identified in photochemical smog. New terms, “PaNs” and “PAN-type” oxidant, have been proffered for purposes of clarification of the terminology. PAN-type oxidant more precisely defines the phytotoxicant complex causing silvering or bronzing of the lower leaf surfaces in lieu of the older term “oxidant.” Due to the recognition of several oxidizing phytotoxicants in recent years, it is recommended that the term oxidant be reserved for use as a generic term. A tabular classification of the oxidizing phytotoxicants found in community photochemical smog and the specific syndromes produced is provided.     

Effects of Vertical Temperature Difference on Soiling Index

Changes in contaminant levels at monitoring stations do not necessarily represent changes in emission levels, since variations in meteorological parameters determine the transport and diffusion of contaminants between sources and receptors. To estimate annual changes in emission levels, and thus of control program effectiveness, the meteorological stratification of data was employed to provide “comparable days.”

For San Francisco Bay Area photochemical oxidant data, simple criteria based on maximum temperature and on height of inversion base were selected. Temperature provided a readily available integrated index of solar energy input and of ventilation, while the inversion data added a vertical dilution factor.

An earlier study, employing only the temperature criteria, showed that oxidant levels on comparable warm days had nearly doubled from 1954 through 1962. The current study of oxidant data for 1962 through 1969 shows a gradual rise through 1965, and a sharp reversal in 1966, when for the first time a simultaneous decrease was noted at each benchmark station. Data through 1969 show that average oxidant levels have been maintained at this 25% lower plateau, with minor fluctuations at individual stations.

The general improvement in air quality since 1965 is attributed to the reduction of reactive organics emitted from stationary and automotive sources.     

Ambient Oxidant Exposure andHealth Costs in the United States—1973

The body of information presented in this paper is directed to policy makers and administrators involved in the evaluation and assessment of damages caused by oxidant air pollution on human health and welfare and of possible benefits of control.

To provide a comparison of some of the benefits that can be obtained by reducing photochemical oxidant levels, estimated health costs were derived from data relating adverse health effects to hourly oxidant concentrations. Hourly oxidant or ozone concentrations were measured at approximately 400 monitoring stations scattered throughout the U.S. Most of these sites were located in major urban areas or in other areas where high oxidant concentrations prevailed. Estimates of populations at risk and per capita health costs were generated for those areas where oxidant data was available.

During the period 1971-1973, nearly two-thirds of the U.S. population resided in areas where the hourly primary standard for oxidants of 160 µg/m³ was exceeded. The total annual health cost attributable to oxidants was estimated to range from $120 to over $240 million in the U.S.     

Perchlorate as an environmental contaminant

Perchlorate anion (ClO4-) has been found in drinking water supplies throughout the southwestern United States. It is primarily associated with releases of ammonium perchlorate by defense contractors, military operations, and aerospace programs. Ammonium perchlorate is used as a solid oxidant in missile and rocket propulsion systems. Traces of perchlorate are found in Chile saltpeter, but the use of such fertilizer has not been associated with large scale contamination. Although it is a strong oxidant, perchlorate anion is very persistent in the environment due to the high activation energy associated with its reduction. At high enough concentrations, perchlorate can affect thyroid gland functions, where it is mistakenly taken up in place of iodide. A safe daily exposure has not yet been set, but is expected to be released in 2002. Perchlorate is measured in environmental samples primarily by ion chromatography. It can be removed by anion exchange or membrane filtration. It is destroyed by some biological and chemical processes. The environmental occurrence, toxicity, analytical chemistry, and remediative approaches are discussed.     

Simultaneous Total Oxidant and Chemiluminescent Ozone Measurements in Ambient Air

The purpose of this project was to investigate the relationship of ambient air quality measurements between two analytical methods, referred to as the total oxidant method and the chemiluminescent method. These two well documented analytical methods were run simultaneously, side by side, at a site on the Houston ship channel. They were calibrated daily. The hourly averages were analyzed by regression techniques and the confidence intervals were calculated for the regression lines. Confidence intervals for point estimates were also calculated. These methods were used with all data sets with values greater than 10 parts per billion and again with values greater than 30 parts per billion. A regression line was also calculated for a second set of data for the preceding year. These data were generated before a chromium triox-ide scrubber was installed to eliminate possible chemical interferences with the Kl method.

The results show that in general the chemiluminescent ozone method tends to produce values as much as two times higher than the simultaneous total oxidant values. In one set of data collected an 80 ppb chemiluminescent ozone value predicted a value of 43.9 ppb total oxidant with a 95% confidence interval of 7.7 to 80.4 ppb. In the second set of data an 80 ppb chemiluminescent ozone value predicted a value of 78 ppb total oxidant with a 95% confidence interval of 0.4 to 156 ppb. Other statistical analyses confirmed that either measurement was a very poor predictor of the other.     

Control of Photochemical Smog by Alteration of Initial Reactant Ratios

This paper is an endeavor to show how several experimenters have quite closely equaled the results of the other, and how the results from these various laboratories can, by a change of coordinate system, be related to each other in a systematic manner. Only after demonstrating where the Los Angeles Civic Center atmosphere is in relation to these coordinates and the contours, or gradients, of these various effects, eye irritation and oxidant, is it possible to predict the photochemical effect of a reduction of olefins (hydrocarbons) or the reduction of nitric oxide. In addition, a study of the variation in eye irritation with irradiation time, demonstrates that the time at which eye irritation measurements are taken is important in understanding the entire photochemical mechanism underlying the “smog” problem in the summertime in Los Angeles     

Air Quality Criteria—Toxicological Appraisal for Oxidants,Nitrogen Oxides,and Hydrocarbons

The ultimate aim of toxicological studies is to determine the effects of pollutants on the health and welfare of human beings. To get this it is essential to conduct animal studies to evaluate the potential toxicity of different pollutants. Toxicological appraisal of the photochemical oxidant type of air pollution shows: (1) The effects are primarily on the lungs and the senses. (2) There is impairment of pulmonary function in humans at concentrations found in polluted air. (3) Both ozone and nitrogen dioxide tend to oxidize in animals the lung tissue for a time. This process creates agents which have the potential for cross-linking structural proteins, and this process initiates inflammation which accelerates cell turnover rates. Both crosslinking and cell turnover rates are factors in aging, which may thus be accelerated by years of repeated exposure to oxidants. (4) Long-term exposure to low levels of nitrogen dioxide can produce pre-emphasematous lesions in the lungs of rats and mice. Studies with other species are needed. (5) Ozone, nitrogen dioxide, and dilute irradiated car exhausts increase susceptibility to respiratory infection.

The constant search for more sophisticated and sensitive techniques to detect subtle changes indicative of pre-disease conditions should not be relaxed. Such techniques will provide chronic disease predictors of great relevance as air quality criteria.     

Relationship of Hydrocarbons to Oxidants in Ambient Atmospheres

The relation of ambient levels of hydrocarbons to the products of atmospheric photochemistry has proved to be an elusive problem. Models to account for the photochemical processes are available based on laboratory examination of simulated atmospheres. Likewise, dispersion models are available which, for nonreacting species, can predict air quality given knowledge of emission rates and meteorological variables. However, integration of the dispersion model with the photochemical model is as yet an unsolved problem. In this study an empirical approach was applied in which the only assumption made was that there exists a relationship between early morning average hydrocarbon concentrations and subsequent maximum hourly average oxidant concentrations. A direct examination of all available days in several cities shows that, at any given hydrocarbon level, there exists a limit on the amount of oxidant which can be generated. Specifically it shows that the average 6:00–9:00 A.M. concentration of 0.3 ppm C nonmethane hydrocarbon can be expected to produce a maximum hourly average oxidant concentration of up to 0.1 ppm.     

Smog Chamber Simulation of Los Angeles Pollutant Transport

The body of information presented in this paper is directed to those individuals concerned with the effect of urban pollution on downwind areas. In the absence of any evidence, it has been widely assumed that increasing NO _x emissions have caused oxidant levels to increase downwind of Los Angeles, i.e., Riverside and San Bernardino. This smog chamber study simulated pollutant transport from Los Angeles to the downwind areas by irradiating a typical Los Angeles hydrocarbon/NO _x mixture for extended periods of time. The smog chamber experiments were extended to 22 hours to obtain an integrated light intensity equal to that which occurs in the Los Angeles area. The effects of variations of nitrogen oxide emissions on an aged air mass were examined. The results show that downwind oxidant levels are only slightly affected by large changes in NO _x emissions. However, it is clear that reduced nitrogen oxide emissions will lead to an increase in oxidant in downtown Los Angeles.     

喹禾灵含酚废水混凝氧化效果的试验研究

选用三氯化铁作混凝剂,次氯酸钠作氧化剂,研究了混凝剂和氧化剂的投加量、pH及不同的反应时间对喹禾灵含酚废水处理效果的影响。试验结果表明,混凝剂最佳投加量为8．0g／L,最佳pH为9～10;氧化剂最佳投加量为50mL/L(有效氯为5．2％)．最佳pH为2～3。在最佳条件下,废水经混凝氧化后,其CODc,、对苯二酚、色度的去除率分别达98．12％、97．26％、99．00％。     

California Statewide Assessment of the Effects of Ozone on Crop Productivity

Six properties appear desirable for any set of ozone attainment criteria: (1) sufficient stringency to protect public health, (2) simplicity and understandability, (3) sensitivity to real changes in air quality, (4) stability against meteorological fluctuations, (5) use of as much data as possible, and (6) equivalence between the stringency the criteria appear to mandate, and what they actually mandate. We consider how the federal attainment criteria might be improved with respect to Properties 4 through 6 while being equally strong on 1 through 3. Whether the federal standard meets Property 1 has been the subject of debate, but our analysis would apply also to a modified standard. We show that there are subtleties in how improvements might be made. In particular, basing the attainment status on a statistic with low variance may not lead to a more stable criterion, and although it is easy to find a criterion that makes it hard for a district with bad air to reach attainment, or a district with good air to get out of attainment, it is hard to find a criterion that does both. This suggests using different criteria for districts that are out of attainment from districts that are in attainment. Initially the burden of proof would be on the district to prove that its air is of attainment quality. However, once the district has achieved attainment the burden of proof would shift; the district would remain in attainment unless there was strong evidence to the contrary. An evaluation of a set of criteria based on this idea showed improvements over the federal criteria with respect to the last three desirable properties-stability, use of data, and equivalent stringency-with some sacrifice in simplicity and sensitivity.     

Current Research on Aerosols at Pacific Northwest Laboratory1

Construction of a new bridge span over San Francisco Bay in the summer of 1967 made feasible for the first time continuous measurement of oxidant levels at a mid-bay site. Hypotheses of higher or lower oxidant levels over a central body of water in an urban complex could thus be evaluated. No significant bay effect, positive or negative, was found in the mean data, but analysis on a case basis showed that conditions favoring adverse oxidant development over the region favored even higher levels over the bay itself. Patterns of oxidant concentration reinforced by the mid-bay data show a broadly distributed community air pollution level, and they support the mixing of oxidant precursors from area-wide sources so that the bay and the surrounding land are equally involved as sites for the photochemical process of oxidant formation.     

Rethinking the ozone standard

Six properties appear desirable for any set of ozone attainment criteria: (1) sufficient stringency to protect public health, (2) simplicity and understandability, (3) sensitivity to real changes in air quality, (4) stability against meteorological fluctuations, (5) use of as much data as possible, and (6) equivalence between the stringency the criteria appear to mandate, and what they actually mandate. We consider how the federal attainment criteria might be improved with respect to Properties 4 through 6 while being equally strong on 1 through 3. Whether the federal standard meets Property 1 has been the subject of debate, but our analysis would apply also to a modified standard. We show that there are subtleties in how improvements might be made. In particular, basing the attainment status on a statistic with low variance may not lead to a more stable criterion, and although it is easy to find a criterion that makes it hard for a district with bad air to reach attainment, or a district with good air to get out of attainment, it is hard to find a criterion that does both. This suggests using different criteria for districts that are out of attainment from districts that are in attainment. Initially the burden of proof would be on the district to prove that its air is of attainment quality. However, once the district has achieved attainment the burden of proof would shift; the district would remain in attainment unless there was strong evidence to the contrary.(ABSTRACT TRUNCATED AT 250 WORDS)     

Eco-Labelling of Shampoos,Shower Gels and Foam Baths (6 pp)

GOAL, SCOPE AND BACKGROUND: Environmental issues of personal care products have been met with little attention in the past. Monitoring data as well as preliminary environmental risk assessments indicate that some ingredients in personal care products might be relevant pollutants in the environment. Following the precautionary principle, eco-labelling is proposed as an effective tool for source control of one major group of personal care products, shampoos, shower gels and foam baths (SSBs). Eco-labelling is a soft, but effective market driven and product specific approach to lower discharge of environmentally detrimental substances. Products that fulfil the criteria proposed help to minimise the impact of SSBs on the environment. METHODS: Available assessment tools for dangerous substances (e.g. current legislation on environmental risk assessments and classification, and labelling, eco-labelling criteria for similar products, the calculation of the critical dilution volume) were adapted and integrated into the criteria for the eco-labelling of SSBs. RESULTS AND DISCUSSION: A short outline of the eco-labelling criteria developed for SSBs is provided. The basic criteria concern the effects of the substances discharged into the waste water during and after use. Products with an eco-label award may exclusively contain substances for which basic information about their effects on the environment is available. They may not contain persistent, bioaccumulating, toxic or ecotoxicological substances. In addition, the basic criteria include requirements for the container and consumer information. CONCLUSION: The basic criteria for eco-labelling SSBs are based on the actual state of science and are at the same time as simple and transparent as possible to ensure the best applicability. SSBs that comply with the described basic criteria can contribute to a lower chemical burden of waste water treatment plants and surface water. RECOMMENDATION AND OUTLOOK: The proposal for basic criteria described should stimulate discussion on eco-labelling of SSBs. It should help to pass valid criteria supported by authorities, producers and consumer groups for a national or international eco-label, e.g. for the European Flower or the German Blue Angel. In future, the successful introduction of labelled SSBs into the market will raise the awareness of the general public about the environmental effects of personal care products and it will help to promote environmentally compatible products.     

Riparian rehabilitation planning in an urban–rural gradient: Integrating social needs and ecological conditions

In the present context of global change and search for sustainability, we detected a gap between restoration and society: local communities are usually only considered as threats or disturbances when planning for restoration. To bridge this gap, we propose a landscape design framework for planning riparian rehabilitation in an urban–rural gradient. A spatial multi-criteria analysis was used to assess the priority of riversides by considering two rehabilitation objectives simultaneously—socio-environmental and ecological—and two sets of criteria were designed according to these objectives. The assessment made it possible to identify 17 priority sites for riparian rehabilitation that were associated with different conditions along the gradient. The double goal setting enabled a dual consideration of citizens, both as beneficiaries and potential impacts to rehabilitation, and the criteria selected incorporated the multi-dimensional nature of the environment. This approach can potentially be adapted and implemented in any other anthropic–natural interface throughout the world.     

Changes of turbidity during the phenol oxidation by photo-Fenton treatment

Turbidity presented by phenol solutions oxidized with Fenton reagent shows the tendency of a first order intermediate kinetics. Thus, turbidity can be considered a representative parameter of the presence of intermediate oxidation species, which are generated along the decomposition of toxic and reluctant contaminants, such as phenol. Moreover, that parameter presents a linear dependence with the catalyst dosage, but is also determined by the initial contaminant load. When analyzing the oxidation mechanism of phenol, it is found that the maximum turbidity occurs when the treatment is carried out at oxidant to phenol molar ratios R?=?4.0. These oxidation conditions correspond to the presence of a reaction mixture mainly composed of dihydroxylated rings, precursors of the muconic acid formation. The oxidation via “para” comprises the formation reactions of charge transfer complexes (quinhydrone), between the para-dihydroxylated intermediates (hydroquinone) and the para-substituted quinones (p-benzoquinone), which are quite unstable and reactive species, quickly decomposed into hydroxyhydroquinones. Working with oxidant ratios up to R?=?6.0, the maximum observed value of turbidity in the oxidized solutions is kept almost constant. It is found that, in these conditions, the pyrogallol formation is maximal, what is generated through the degradation of ortho-species (catechol and ortho-benzoquinone) and meta-substituted (resorcinol). Operating with ratios over R?=?6.0, these intermediates are decomposed into biodegradable acids, generating lower turbidity in the solution. Then, the residual turbidity is a function of the molar ratio of the ferrous ions vs. moles of oxidant utilized in the essays, that lets to estimate the stoichiometric dosage of catalyst as 20 mg/L at pH?=?3.0, whereas operating in stoichiometric conditions, R?=?14.0, the residual turbidity of water results almost null.     

The Utilization of Optimum Meteorological Conditions for the Reduction of Los Angeles Automotive Pollution

Advantage can be taken of optimum conditions of turbulent mixing to decrease the intensity of automobile-caused pollution in the Los Angeles Basin. Changing the summertime peak traffic hours—delaying the morning rush by one hour—will result in an improvement of 24 percent for an eight-hour day, in terms of oxidant concentrations. Greater improvements (up to 54 percent) are possible by use of seven or six-hour days, should they be found to be economically feasible.     

Canadian Activities in Ambient Air Quality Criteria and Development of Standards

Within recent years, increasing attention has been directed to the determination of contaminant levels in urban and industrial areas involving particulate matter (dustfall, suspended matter and smoke), sulfur dioxide, hydrogen sulfide, fluorides, ozone or oxidant, oxides of nitrogen and polycyclic aromatic hydrocarbons. However, with regard to criteria and evaluation of effects, none of these pollutants has been studied as thoroughly as sulfur dioxide. Presently, three provinces in Canada have adopted acts or regulations dealing with the control of air pollution. The Ontario Act, passed in 1958 and amended in 1963 and 1964, is the most comprehensive in scope. The Damage by Fumes Arbitration Act of Ontario provides for the awarding of compensation where crops, trees or other vegetation is damaged by sulfur fumes arising from the smelting or roasting of nickel-copper ore or iron ore or from the treatment of sulfides for the production of sulfur of sulfuric acid for commercial purposes. Regulations have also been enacted in Manitoba and Alberta. A provincial act is under consideration in Saskatchewan.     

Design of A Large Scale Exposure and Sampling Facility for Street Level Auto Exhaust Emissions

A unique air handling facility was designed to introduce up to 12,000 cfm of street level air into laminar flow animal exposure chambers in an unaltered state except for the heating and cooling necessary in extreme weather to provide the animals with an habitable climate. The facility was built to determine the possible effect of street level exhaust emissions on the health of the general population. Another objective was to determine, by means of direct reading and recording instruments, the concentration of contaminants such as carbon monoxide, carbon dioxide, aerosols, nitrogen oxides, total oxidant, and unburned hydrocarbons.