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Ambient air pollutants have detrimental effects on human health and ambient air quality in central Taiwan is worsening. The aims of this study are as follows: (1) Measure the ambient air concentrat...

In this study, the total suspended particulate (TSP) concentrations and dry deposition of ambient air particulates are measured using a high-volume air sampler and a dry deposition plate at an agri...

The drastic increase in atmospheric pollutants has resulted in the prevalence of hazardous diseases like Asthma, Ischaemic heart disease, and Pulmonary disease around the world. IoT technology has ...

The United Arab Emirates (UAE) has seen an increase in oil extraction and oil refining processes. Toxic pollutants such as sulphur dioxide (SO2), black carbon (BC), carbon monoxide (CO) and organic...

In this study, the authors endeavored to develop an effective framework for improving local urban air quality on meso-micro scales in cities in China that are experiencing rapid urbanization. Within this framework, the integrated Weather Research and Forecasting (WRF)/CALPUFF modeling system was applied to simulate the concentration distributions of typical pollutants (particulate matter with an aerodynamic diameter10 μm [PMThe authors endeavored to build up an effective framework based on the integrated WRF/CALPUFF to improve the air quality in many cities on meso-micro scales in China. Via this framework, the integrated modeling tool is accurately used to study the characteristics of meteorological fields, concentration fields, and source apportionments of pollutants in target area. The impacts of classified sources on air quality together with the industrial characteristics can provide more effective control measures for improving air quality. Through the case study, the technical framework developed in this study, particularly the source apportionment, could provide important data and technical support for policy makers to assess air pollution on the scale of a city in China or even the world.

Concentrations of fine particulates (PM2.5) and metallic elements at three sites in central Taiwan (an urban site, a science park, and a site close to traffic), where the mean wind speed was only 1.5 m/s, were monitored and analyzed. The urban site had the lowest TSP and PM2.5 particulate concentrations in winter. The mean concentrations of metallic elements Ni, Pb, and Cr in PM2.5 exceeded those in TSP at the three characteristic sampling sites in winter. A northeasterly monsoon, slowly moving northern cold air masses, and wind with a low average speed (1.5 m/s) dominated during the sampling period. Atmospheric diffusion was generally low, causing large amounts of local atmospheric pollutants to accumulate. The concentrations of metallic elements that were attached to particulates (PM2.5) increased significantly during the winter season. However, the concentrations of particulate pollutants in ambient air declined throughout the winter. The average TSP and PM2.5 particulate concentrations in ambi...

With growing energy needs, depletion of fossil fuel resources and the alarming increase in atmospheric pollutants, the entire world is slowly switching to alternatives. There are many benefits of u...

In recent years, China’s new coal chemical industry (NCCI) advanced quickly, which led to serious and widely concerned air pollution. Emission standard is an important means for the management of atmospheric pollutants from NCCI, and thus plays key roles not only in reducing pollutant emissions, preventing environmental risks and improving environmental quality, but also in promoting the optimization and adjustment of industrial structure as well as the industrial healthy development. Here we discuss the problems of emission standards applied in managing atmospheric pollutants from NCCI based on the project analysis of atmospheric pollutants. The analysis indicates that the atmospheric pollutants from this industry include mainly sulfur dioxide, particulate matter, nitrogen oxides, ammonia, hydrogen sulfide, non-methane total hydrocarbon, hydrogen cyanide, benzo (a) pyrene, benzene, and heavy metals. The existing standards, such as Integrated Emission Standard of Air Pollutants (GB 16297-1996), Em...

Preterm birth is a significant public health concern, as it is associated with high risk of infant mortality, various morbidities in both the neonatal period and later in life, and a significant societal economic burden. As many cases are of unknown etiology, identification of the contribution of environmental contaminant exposures is a priority in the study of preterm birth. This is a comprehensive review of all known studies published from 1992 through August 2012 linking maternal exposure to environmental chemicals during pregnancy with preterm birth. Using PubMed searches, studies were identified that examined associations between preterm birth and exposure to five categories of environmental toxicants, including persistent organic pollutants, drinking-water contaminants, atmospheric pollutants, metals and metalloids, and other environmental contaminants. Individual studies were summarized and specific suggestions were made for future work in regard to exposure and outcome assessment methods as well as study design, with the recommendation of focusing on potential mediating toxicological mechanisms. In conclusion, no consistent evidence was found for positive associations between individual chemical exposures and preterm birth. By identifying limitations and addressing the gaps that may have impeded the ability to identify true associations thus far, this review can guide future epidemiologic studies of environmental exposures and preterm birth.

In European countries and North America, people spend 80 to 90% of time inside buildings and thus breathe indoor air. In Switzerland, special attention has been devoted to the 16 stations of the national network of observation of atmospheric pollutants (NABEL). The results indicate a reduction in outdoor pollution over the last ten years. With such a decrease in pollution over these ten years the question becomes: how can we explain an increase of diseases? Indoor pollution can be the cause. Indoor contaminants that may create indoor air quality (IAQ) problems come from a variety of sources. These can include inadequate ventilation, temperature and humidity dysfunction, and volatile organic compounds (VOCs). The health effects from these contaminants are varied and can range from discomfort, irritation and respiratory diseases to cancer. Among such contaminants, environmental tobacco smoke (ETS) could be considered the most important in terms of both health effects and engineering controls of vent...

Stainless steel grade AISI304 is the largest tonnage alloy material used for industrial and domestic purposes in Saudi Arabia. The primary property, which determines its use in many applications, is its corrosion resistance in a wide variety of aqueous environments. The aim of this study is to evaluate the joint effect of marine and industrial pollutants on the atmospheric degradation of AISI304. The corrosion rate of specimens was determined after one, two, three and four years of exposure by weight loss. The time of wetness and deposition rates of atmospheric pollutants (Cl– and SO2) was also determined. The ISO 9223 standard for atmospheric aggressivity has been applied to the different test sites used. The results agreed well with the empirical kinetics equation of the form C=Ktn, where K and C are the corrosion losses in mg cm–2 after 1 and t years of the exposure respectively, and n is constant. Based on n values, the corrosion mechanism of AISI304 is predicted. Characterisation of the corro...

The relationship of exhaled ethane and n-pentane to exhaled NO, carbonylated proteins, and indoor/outdoor atmospheric pollutants were examined in order to evaluate ethane and n-pentane as potential markers of airway inflammation and/or oxidative stress. Exhaled NO and carbonylated proteins were found to have no significant associations with either ethane (p = 0.96 and p = 0.81, respectively) or n-pentane (p = 0.44 and 0.28, respectively) when outliers were included. In the case where outliers were removed n-pentane was found to be inversely associated with carbonylated proteins. Exhaled hydrocarbons adjusted for indoor hydrocarbon concentrations were instead found to be positively associated with air pollutants (NO, NO(2) and CO), suggesting pollutant exposure is driving exhaled hydrocarbon concentrations. Given these findings, ethane and n-pentane do not appear to be markers of airway inflammation or oxidative stress.

The growing interest in obtaining rapid and more reliable data on air quality indicates a need for non-stationary (transportable and portable) instrumentation. This trend results in the designing and manufacturing of new instruments that are more sensitive, selective, precise and accurate. This paper presents some examples of new instrumentation based on different principles. In the first part, a general classification of devices used for air monitoring and analysis is presented. Finally, the mobile monitoring system (MMS) proposed by the authors for air monitoring along communication lanes is briefly described.

Despite the well-documented negative impacts of ozone on the health of coniferous forests in southern California and the significant growth experienced by southwestern cities over the past several decades, the ozone/forest dynamic in the interior portion of the southwestern United States has been largely ignored. Primarily through a review of literature pertaining to most aspects of ozone and its impact on forest health, this article provides insights on the ozone/forest dynamic within coniferous forests of the interior Southwest. It is suggested that ozone absorption in southwestern coniferous forests may equal that in southern California, owing to the long-distance transport of atmospheric pollutants into the interior Southwest and the presence of the North American monsoon. Nevertheless, research gaps identified in this article suggest a need for future research on ozone exposure levels and the ozone sensitivities of conifer species and varieties in southwestern coniferous forests.

Chlorofluorocarbons are man-made long lasting atmospheric pollutants of great environmental concern, responsible for important global change phenomena. Recently, they were replaced by hydrogenated halocarbons that, even if less persistent, do not lack in environmental impact. Atmospheric concentrations of these compounds were measured in Antarctica by gas chromatography. The extremely low atmospheric mixing ratios of these compounds require a pre-concentration step of the air sample on suitable adsorbent in order to meet the sensitivity of the analytical method Results obtained analyzing air samples collected in Antarctica since 1988 for the determination of CFC-12 and CFC-11 are reported, together with data concerning the less abundant species.

A UNESCO designated World Heritage Site, the city of Bath has many important listed buildings largely constructed of limestone from local quarries. Among present day atmospheric pollutants, SO2 is ...

Studies on the effect of various atmospheric pollutants, such as SO2, NOx and suspended particulate matter, and other environmental parameters like rainfall, percentage relative humidity, wind dire...

Dry deposition pollutants were studied in Taiwan and compared with those reported in other areas of the world. The mean dry deposition fluxes in Taiwan were 2.40, 4.98 and 2.47 nm/m2/sec for Taichung, Tainan and Pingtung, respectively. The correlation coefficients (R2) of mean dry deposition mass flux vs. wind speed were 0.47, 0.90 and 0.69 for Taichung, Tainan and Pingtung, respectively. Dry deposition mass fluxes in Taiwan were the same as in Chicago and about 3 times higher than in the North Sea. Suspended particle concentrations of metal elements (Ca, Fe, Zn, Cu and Cd) in Taiwan were much higher than in Chicago, Olympic and Ventura. The results suggest that there is a greater heavy metal elements problem in Taiwan. The average dry deposition fluxes of total‐PAHs in Taiwan were 622, 529 and 575 μm/m2/sec at these three sampling sites. These were higher than reported in the Great Lakes, Siskiwit Lake and Chesapeake Bay, but were about the same as in Chicago. The total PAH compositions at the t...

The allergenic potency of pollen has been reported to be increased when exposed to atmospheric pollutants like SO2, NO2, etc. The present investigation was undertaken to study the effect of SO2pollution on protein content as well as the allergenic potency of the pollen of Argemone mexicana L. The pollen of this plant was fumigated with SO2 at a concentration of 100 ppm for 24 hours, 48 hours and 72 hours and the soluble protein content and the electrophoretic profile were studied. SDS‐PAGE revealed the appearance of a new protein band with the simultaneous disappearance of two other bands. Protein content showed a gradual decrease with the increase in time of exposure to SO2. Skin‐prick test were performed with the antigens of the normal as well as SO2 fumigated pollen. The skin prick test sensitivity and percentage of patients showing positive response increased with time of fumigation.

Presented is a Monte Carlo model for the simulation of regional scale transport, transformation, and dry and wet removal. The model was newly re-designed in a modular framework, separating the emissions, transport, and kinetics calculations. The transport module employs a quantized Monte Carlo technique for the simulation of atmospheric boundary-layer physics. Kinetic processes are simulated using rate equations where the rate coefficients are dependent upon meteorological variables, and consequently fluctuate in space and time. The rate coefficient equations are determined via a tuning process comparing simulated to observed measurements. Results from simulations of SO2 and SO42- over the eastern United States during 1992 are presented. Comparisons of simulated daily SO4 2- concentrations to observations had a rate of r2 = 0.35-0.83 depending on season and location. The rate for weekly SO42- wet deposition rates was r2 = 0.5-0.95. The utility of the model to investigate the source receptor relationship is demonstrated by explicitly examining the role of emission rates, transport, and kinetic processes in the attribution of sulfur dioxide and sulfate at a receptor in Massachusetts during the summer of 1992.

The Environmental Protection Agency's National Center for Environmental Assessment is currently revising and updating its approach to modeling the health risks from indirect exposure to combustor emissions. The updated method is intended to provide the necessary tools for estimating these health risks and to provide the necessary algorithms for the calculation of contaminant concentrations in water bodies, soil, and the terrestrial and aquatic food chains resulting from the deposition and transfer of atmospheric pollutants. Significant additions to the approach include the expansion of the application of exposure methods at a site, the description of procedures for defining the study population at a site, and ways to develop distributions of individual risk for members of the study population. This paper focuses on the changes in the human exposure scenarios of the updated method and presents an overview of the development of an exposure scenario.

Since the early studies on the genetic effects of chemical and physical agents, species and clones of Tradescantia have been used as experimental subjects, by virtue of a series of favorable genetic characteristics. Bearing just six pairs (2n = 12) of large, easily observable chromosomes, cells from almost every part of the plant, from the root tips to the developing pollen tube, yield excellent material for cytogenetic studies. As a consequence of the intensive use of Tradescantia in genetic studies, a series of genetic characteristics have been found that offer opportunities for the detection of agents affecting the stability of the genome. At least five such characteristics have been selected as endpoints for the establishment of assays to evaluate mutagenesis. Three of these, root-tip mitosis, pollen-tube, and microspore mitosis are essentially chromosome aberration assays, wherein one observes and evaluates the visible damage in the chromosomes. A fourth, the stamen-hair mutation assay (Trad-SHM), is a point mutation mitotic assay based on the expression of a recessive gene for flower color in heterozygous plants. The fifth assay is a cytogenetic test based on the formation of micronuclei (Trad-MCN) that result from chromosome breakage in the meiotic pollen mother cells. This article examines the characteristics and fundamentals of the Trad-MCN and the Trad-SHM assays and reviews the results obtained to date with these systems in the assessment of environmental mutagenesis. Made available in DSpace on 2017-03-01T23:44:20Z (GMT). No. of bitstreams: 1 1997AP044RodriguesTradescantia3350.pdf: 2054243 bytes, checksum: f9ec56277abbb7efe03928cbbdd76a57 (MD5) Previous issue date: 1997-10-22

A large number of 24-hour high-volume samples of respirable air particulate were collected on Teflon/glass filters in Hamilton, Ontario. A series of representative filters were selected for extraction, and examined using a combination of liquid chromatographic, GC/MS and bioassay techniques. A selected group of polycyclic aromatic compounds (PAC), including a number of hydrocarbons, nitroarenes, thia-arenes and oxygen-containing PAC, were identified in thirty-three particulate extracts for correlation with the mutagenic responses for each extract using a Salmonella strain (YG1021) which responds well to nitroarenes. A good correlation was found for mutagenic potency and weight of nonpolar PAC in the data set presented. The atmospheric transformation product 2-nitrofluoranthene was identified as a major source of mutagenic potency in one heavily loaded particulate sample. The relationship between the levels of PAC and/or the mutagenicity in the extracts as a result of exposure to atmospheric pollu...

This paper discusses the development of an alternative technology to sample separately the gas and particulate phases of atmospheric pollutants. The key feature of this technique is the utilization of a slit nozzle virtual impactor with a small 50% cutpoint (0.1 µm) to sample atmospheric pollutants at high flow rates (225 LPM). In contrast to the diffusion denuder/filter pack and impactor/filter pack techniques, which collect gas and particulate phases sequentially, the two phases are separated in a virtual impactor and collected independently, to eliminate sampling artifacts. The virtual impactor has been characterized in laboratory studies using fluorescent monodisperse aerosols, and in field studies by comparing its performance to the performance of a collocated dichotomous sampler. The results indicate that the minor flow (consisting of particles in the range 0.1

The resistance of metals to atmospheric corrosion is of broad interest because of the many structures and products exposed to the air. Atmospheric corrosion phenomena are induced or assisted by different atmospheric pollutants, mainly sulphur dioxide and chloride ions. Corrosion results for zinc obtained over a 3 year period in natural environments are reported. Climatic characteristics showed a significant effect on corrosion behaviour. Experimental data were subjected to statistical treatment and to regression analysis using standard computer programs.

The analysis of pollutants trapped on a motor vehicle air/pollen filter provides valuable information on atmospheric quality. The technique described is both accurate and rapid and has potential applications in comparative studies in diverse geographical areas with differing atmospheric pollution problems. The filter was particularly effective and removed an additional six elements to those contained in the control filter material. The probable sources of some of the elements is discussed.

A stripping technique has been used to cencentrate selected hydrocarbons present in water samples at the parts per billion level for analysis by gas chromatography. The chromatograms of hydrocarbons thus stripped from several different water samples show similarities. Washing out of atmospheric pollutants by rainfall is postulated as an explanation of these results. This hypothesis is supported by a comparison of the data with those for trace atmospheric analysis. The comparison shows that the same compounds are present in similar relative amounts both in water samples and the atmosphere. After a period of rain the atmospheric concentrations decrease whilst the water bound concentrations increase.

Atmospheric pollution attributed to increased combustion of fossil fuels has been implicated as a possible contributory factor in observed changes to forests in North America and Europe. This review aims to evaluate evidence of changes in growth and vitality of trees in present-day forests; to compare levels of principal atmospheric pollutants in Europe and the US; to describe mechanisms and concentration thresholds for effects of principal pollutants on tree growth and physiology; and to summarise current evidence for the role of pollution in observed forest declines. Evidence from research is examined to provide a basis for evaluating the role of atmospheric pollution in present and potential future forest responses. There is a bibliography, of more than 200 references.

Gas chromatography has been applied to the determination of a number of trace hydrocarbons in the atmosphere after concentration on active carbon. The concentrations of selected compounds have been measured at four locations during two hour periods throughout at least 20 days over a period of one year. A diurnal pattern of concentration variation is demonstrated. Concentration maxima at each location occur at times of peak road traffic density. The results of different analytical investigations can be compared only if the sampling periods are identical.

Photography has had a profound effect upon the development of nineteenth and twentieth century society bringing about enormous advances in the sciences, art, and technology whilst stimulating a huge surge in social and political awareness. This valuable visual legacy and sociological record spanning a mere 144 years is being lost at an alarming rate. Photographs exist on four distinct levels and are susceptible to degradation on all of them. It is the extremely unstable and highly sensitive combination of physical and chemical properties that makes them so vulnerable to even the smallest concentrations of atmospheric pollutants and material contaminants. This paper shows that safe, practical conservation techniques have been developed. It is also clearly shown that conservation ethics and standards have played a major part in the research and the resulting practical techniques.

An instrumented aircraft was used to study the chemical and transport properties of air pollution in two major urban centers in California and to survey certain aspects of air pollution within this state. State-of-the-art measurement techniques and sampling procedures are discussed. It is found that meteorological transport mechanisms are better portrayed by vertical pollutant profiles. Airborne measurements define the nature of the mixing layer for atmospheric pollutants. Results show that the pollutants are found to be concentrated in distinct layers up to at least 18,000 feet and the O3 buildup occurring in advected air masses is a result of a continuous photochemical aging of air mass.

The article analyzes possible routes for the transport of atmospheric pollutants into the Arctic. They derive from both local and external sources and accumulate in the snow and ice which can thus be used as natural indicators of the degree of atmospheric pollution and its distribution. Monitoring points for taking samples for pollution studies, located both in polluted areas and pollution‐free areas are proposed. Some areas of the Kola Peninsula and the southern part of the Taymyr Peninsula are identified as polluted regions and Baydaratskaya Gulf and the Kolyma and Indigirka areas as relatively unpolluted regions.

Pure pollen grains of Ulmus pumila, Quercus rubra, Pinus taeda, and Festuca elatior were used as a biological screen to test the effects of certain commonly occurring atmospheric pollutants on pollen wall protein. The pollen grain samples were collected aseptically and contaminated with the gaseous pollutants NO2 (nitrogen dioxide), SO2 (sulphur dioxide)J, and CO (carbon monoxide). After the extracts were analyzed by disk gel electrophoresis, the results indicate that apparent changes occur in the quality of the contaminated pollen wall proteins.

Deposition of atmospheric pollutants is occurring over much of eastern North America. While evidence exists of long-term reductions in pH and alkalinity of sensitive surface waters and adverse impacts on aquatic life, much of it is circumstantial. Cause and effect relationships have not been substantiated and many scientific uncertainties must be resolved before decisions concerning emissions controls can be made. This paper addresses the issues of information gaps, scientific uncertainties, and risks in making policy decisions to protect sensitive lake resources from acid precipitation. Circumstantial evidence may be all that decisionmakers can realistically expect from science in the short term, and information gaps inevitably will remain. On such an issue of public significance as acid precipitation, a cogent understanding of existing scientific facts and the use of prudence and equity are needed on the part of decisionmakers to ensure that necessary steps are taken in the face of uncertainty ...

This research has involved investigation of the simulated atmospheric corrosion of zinc, aluminium and especially iron in situations where particulate pollutants initiate attack at various relative...

Organic polymers often develop yellowish colours as they age. the result of oxidative or degradative processes. Improvements have been made in methods of manufacture and in development of stabilizers to reduce the effects of ageing. This kind of yellowing is unlikely, therefore, to explain the increase in the severity of the problem. When fluorescent brightening agents (FBAs) were introduced, there were instances of yellowing due to the effects of light, of acid, of impurities, or even of concentration. Here too, there have been improvements in the quality and the colourfastness of the compounds used. This type of yellowing is therefore also unlikely to be the principal factor in the problems of the past few years. However, P BAs used in processing in some parts of the world can be of lower stability than the materials used in the UK textile industry. During the period in question there has been a considerable increase in the use of phenol and aromatic amine antioxidants and stabilizers in many commonly available products, e.g. packaging, lubricants and other auxiliaries, foams, elastic and rubberized materials. There has also been an increase in the level of atmospheric pollution, with oxides of nitrogen in areas close to high density of traffic and to gasor oil-fired lieating systems. The resulting yellow products not only cause discoloration, but also quench the fluorescence of white textiles containing fluorescent brightening agents. The number of cases of yellowing of textiles sent to Shirley Institute for investigation has also increased over' the same period. During the past two years the distribution of causes has been as shown in Table i. By far the

Dans ce travail, les interactions de composes aromatiques (toluene, xylene), olefiniques (ethylene, isobutene) et paraffinique (octane) avec le chlore ont ete etudiees en enceinte de simulation. Les conditions choisies (air sec synthetique pur N 48 d'Air Liquide, forte irradiation, agitation) conduisent a la formation de nombreux produits secondaires oxydes, oxychlores et chlores. Les produits sont pieges sur colonne a remplissage (Chromosorb W + SE 30 a – 180°C ou Tenax a temperature ambiante) et analyses par couplage chromatographie en phase gazeuse-spectrometrie de masse. Des prelevements sequentiels permettent de suivre l'evolution de la concentration de certains des composes, soit initiaux, soit formes secondairement. La connaissance des produits obtenus permet d'envisager des mecanismes de reaction impliquant diverses hypotheses reactionnelles (autooxydation radicalaire photoinduite ou photooxygenation). Une etude cinetique partielle permettant de confirmer les mecanismes preconises a egale...

Damage to materials of construction by atmospheric pollutants falls into three categories: corrosion, soiling, and cleaning damage. All three occur in varying degrees in the absence of pollution; to assess the impact of pollutants on materials of construction, therefore, it is necessary to determine the incremental impact attributable to the pollutants. Research to date has tended to the collection of data on effects of inadequately characterized pollutant complexes on inadequately characterized materials, followed by the imposition of arbitrary regression lines on the data, ignoring the underlying chemical kinetics. An outlook on the problem is given and approaches are suggested that will decompose the series of steps into manageable portions. This viewpoint should lead to increased understanding of the phenomena involved and thus to the ability to set rational thresholds of impact as an ingredient in the process of considering the possibility of basing ambient environmental standards on such data.

Cylindrical, all glass, inhalation chambers are described which are suitable for the exposure of small laboratory animals to atmospheric pollutants. The main feature of the design is the ability of the investigator to construct a chamber with an internal volume which best approximates the animal loading requirement and/or the availability of test material. Evaluation of the distribution of a gaseous material within the chamber has shown that animals will be exposed to a specified atmospheric concentration of the material irrespective of their position within the chamber. Catch pans for the collection of excreta can be used which do not affect the uniformity of material distribution. Preliminary evaluation of the distribution of a particulate atmosphere indicates that the same will be true for liquid and solid aerosols.

Experiments were carried out to examine the importance of light as a factor influencing the type and amount of smog damage to plants. The stomatal action of leaves under various light conditions and the correlation of stomatal opening to plant damage from atmospheric pollutants were studied. Results indicated that some other factor than stomates was more important in controlling plant susceptibility to smog. The differences in plant response of various age bean plants suggested that the mechanism of ozone damage is quite different from PAN damage. The relationships between sugar production and ozone damage are examined. 9 references, 11 figures, 2 tables.

A brief survey is given of the sources, the methods of injection into the atmosphere, and the mechanisms of deposition into bodies of water for various atmospheric pollutants which contribute significantly to the pollution of large bodies of water. Specific examples of the relative importance of atmospheric sources are included where data are available. Programs of the Canadian Atmospheric Environment Service in this field of research are outlined.

The paper provides a list of 54 atmospheric corrosion test sites in various localities in Europe available for use for studying the protection of structural steel. The information supplied includes types of climate (rainfall, humidity, sunshine, temperature, etc.), details of atmospheric pollutants, convenient sizes for samples and how they are disposed on the exposure racks. Addresses of organisations in charge of the exposure sites are appended.

Aerosol-induced murine influenza was evaluated as a model through which effects of environmental stresses on the pathogenesis of viral respiratory infection can be studied. Infection rate and amount of pneumonia produced in mice in response to small-particle aerosol exposure to either A2/J305/57 or A/PR8/34 influenza virus are quantitative phenomena closely related to vital exposure dose. Mice are highly susceptible to aerosol-induced influenza infection, ie, one mouse infectious dose (MID50) was equivalent to approximately two to three egg infectious doses. The amount of pneumonia which developed in response to infection and its timecourse was also related to viral exposure dose. Between the dose range of 1 to 100 MID50 the amount of lung consolidation ranged between 25% to 60% The results from exposure to the A2 and PR8 influenza viral subtypes were similar.

Study of the dispersion of atmospheric pollutants has benefited greatly in the past from the use of artificial tracers. The study described in this paper used tethered balloons which carry one end of a hose aloft, through which a gaseous tracer can be dispensed. From the field tests it was concluded that the tandem balloon system is useful in atmospheric tracer experiments where a single balloon has insufficient lift to provide a release at the desired elevation. The SF/sub 6/ release system proved to be portable, easy to use, and suitable for simulating continuous elevated pollutant releases. 3 figures. (DP)

Chlorinated atmospheric pollutants are presently receiving much attention because of expected chlorine-ozone interactions in the stratosphere.1,2 The fully halogenated pollutants,such as CCI3F, CCl2F2, and CCl4, have no known removal processes that operate in the troposphere. These compounds are accumulating on a global scale, their atmospheric mixing ratios having reached about 2 X 10-10 for CCl2F2,1.2 X 10-10 for CCl3F, and 9 X 10-11 for CCl4.3-5

A photodynamic bioassay which can be conducted on one mgm amounts of organic atmospheric particulates is described, using Paramecium caudatum. The results of a pilot study on pollutants from several American cities indicate that the assay may provide a rapid, simple and economical biological index of a potential carcinogenic hazard attributable to polycyclic compounds. The utility of the assay for this purpose is under further evaluation. 15 references, 5 figures, 1 table.

Photogrophs ore susceptible to degradation (rom many sources. Attock on the imoge or bose can occur (rom residual processing chemicals. industrial atmospheric pollutants, contaminants (rom storage area construction materials or (rom the materials used (or mounting and containing the pictures. Degradation (rom poor processing can be detected with simple chemical tests. Until more becomes known about the many products normally associated with the preservation o( photographs, one should avoid using in the storage area fresh point, raw woods and volatile substances, and near or on the photographs avoid adhesives, plastics and poor quality papers. Regardless o( the preservation technique used it is help(ul to remember that the storage li(e of photographs can be extended by slowing down chemical activity. This can be achieved by care(ul control a( storage temperature and relative humidity (60 references).