In the ambient air

Clean Air Act of 1970 The Clean Air Act of 1970 was founded on the concept of attaining National Ambient Air Quahty Standards (NAAQS). Data were accumulated and analyzed to establish the quality of the air, identify sources of pollution, determine how pollutants disperse and interac t in the ambient air, and define reduc tions and controls necessary to achieve air-quahty objectives. 

How does the range of concentrations of air pollutants of concern to the industrial hygienist differ from that of concern to the air pollution specialist To what extent are air sampling and analytical methods in factories and in the ambient air the same or different ... 

The method used to develop the emission inventory does have some elements of error, but the other two alternatives are expensive and subject to their own errors. The first alternative would be to monitor continually every major source in the area. The second method would be to monitor continually the pollutants in the ambient air at many points and apply appropriate diffusion equations to calculate the emissions. In practice, the most informative system would be a combination of all three, knowledgeably applied. 

Similar chemical steps occur in the ambient air and in laboratory smog chamber simulations. Initially, hydrocarbons and nitric oxide are oxidized... 

The principal method used for measuring NO2 is also based on chemiluminescence (Fig. 14-3) (5). NO2 concentrations are determined indirectly from the difference between the NO and NO (NO -I- NO2) concentrations in the atmosphere. These concentrations are determined by measuring the tight emitted from the chemiluminescent reaction of NO with 03 (similar to the reaction of O3 with ethylene noted for the measurement of O3), except that O3 is supplied at a high constant concentration, and the light output is proportional to the concentration of NO present in the ambient air stream. 

Exposure to sulfur dioxide in the ambient air has been associated with reduced lung function, increased incidence of respiratory symptoms and diseases, irritation of the eyes, nose, and throat, and premature mortality. Children, the elderly, and those already suffering from respiratory ailments, such as asthmatics, are especially at risk. Health impacts appear to be linked especially to brief exposures to ambient concentrations above 1,000 ixg/in (acute exposures measured over 10 minutes). Some epidemiologic studies, however, have shown an association between relatively low annual mean levels and excess mortality. It is not clear whether long-... 

Effective inlet air filtration is required to ensure satisfactory operation of the engine. The location of the unit determines the most appropriate filter system to use. Desert environments where a large amount of sand particles could be expected in the ambient air may use an automatic roll type of filter that allows new filter material to be rolled in front of the inlet without frequent shut-downs to change filters. Arctic or extremely cold locations may use pad type filters, snow hoods to prevent blockage, and exhaust recirculation to prevent icing. Filter assemblies for offshore marine environments may include weather louvers, demister pads, and barrier elements for salt and dirt removal. Screens may be u.sed for insect removal prior to filtration in areas with bug problems. 

The ratio of the speed of sound in the compressed nitrogen to the speed of sound in the ambient air, ada, is approximately 1. 

Time Weighted Average Coiiecntration (TWA) The concentration of a substance to which a person is exposed in the ambient air, averaged over a period, usually 8 hours. 

Maas FM, De Kok LJ. 1988. In vitro NADH oxidation as an early indicator for growth reduction of spinach exposed to hydrogen sulfide in the ambient air. Plant Cell Physiol 29 523-526. 

Li YM, Jiang GB, Wang YW, Wang P, Zhang QH (2008) Concentrations, profiles and gas-particle partitioning of PCDD/Fs, PCBs and PBDEs in the ambient air of an e-waste dismantling area, southeast China. Chin Sci Bull 53(4) 521-528. doi 10.1007/sl 1434-008-0125-8... 

Effect of dilution—In addition to the water present in the ambient air, the materials contained a certain amount of water. The water evaporated from the materials diluted the exhaust gases. This water is not accounted for in the chemical expansion factor. The magnitude of the error depends on the evaporation rate of water and the total... 

A straightforward way to measure air quality is to measure the carbon dioxide concentration, which is a natural biological metabolite and increases especially in rooms filled with people. An increase in C02 is mainly responsible for sleepiness and could therefore serve as a direct measure of poor air quality. The base concentration of C02 in the ambient air is around 400 ppm. In non-ventilated rooms the C02-concentration can amount to more than 1000 ppm. Some carbon dioxide concentrations and limits and their impact on human comfort are listed in Tab. 5.4. 

Singh N., Mittal S.K., Agarwal R., Awasthi A. and Gupta P.K., Impact of rice crop residue burning on levels of SPM, SO2 and NO2 in the ambient air of Patiala (India), International Journal of Environmental Analytical Chemistry, 90 (10), 829-843 (2010)... 

The hydrogen sulfide adsorption on the HKUST-l/GO composites was only studied in moist conditions [44]. The choice was based on the presence of water in the ambient air and on the extensive studies of H2S reactive adsorption on carbonaceous materials where water was important for dissociation of hydrogen sulfide before its further reaction with surface active sites [5]. Here up to 20 wt% of H2S was adsorbed in the composite with the smallest content of GO. [44]. An increase in the GO content resulted in a decrease in the capacity but nevertheless it was higher than that on MOF... 

Despite the technical advances in the past decade, no apparatus for measurement of the odour strength has been developed. Therefore, odour pollution studies cannot be performed without using human noses. In general, the efect of polluting odours can be studied either by direct assessment in the ambient air or by means of a dispersion calculation. The first method requires a number of observers to be placed in the vincinity of the odour source (3,7). The latter a dispersion model and an input value. For reasons of simplicity this method is most frequently used in the Netherlands. 

The strength of the odour was estimated by a number of outdoor observers, who compared the odour with a standard reference of pyridine, and by observers sitting in the KI s mobile laboratory who measured the odour in the ambient air. The observers made the determinations at distances ranging from 50 to 400 metres downwind of the manured field. Fig. 4. 

Wright CG, Leidy RB. 1982. Chlordane and heptachlor in the ambient air of houses treated for termites. Bull Environ Contam Toxicol 28 617-623. 

To prevent the formation of reaction products from the interaction of the ozone-air sample with Alters, they arc intentionally not used at probe inlets (see Table 6-4). Some of the newer instruments, however, require Alters at the inlet of their sampling ports to prevent the particulate matter in the ambient air from fouling reaction-chamber cells or from clogging the gas-flow controllers. When the same type of Alter also precedes the calibration and zero gas sampling ports (which has not always been the practice), the problem is minimized to the extent that similar events occur during the calibration and sampling. 

In exposures of humans to artificially generated aerosols, where the information is to be relevant to ambient aerosols, several factors are important the particle diameter distribution must be fairly constant and fall within size ranges typical for the given compound in the ambient air, the chemical composition of the aerosol must be stable and predictable, and the electric charge distribution of the aerosol must simulate that of normal atmospheric aerosols. 

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