Urban environments

This paper describes the construction and use of a diffusion tube for sampling NO2 from the atmosphere. Examples of its use include the determination of NO2 concentrations at various heights above ground level in an urban environment and through a tree s leaf canopy. 

Total airborne particulates are determined using a high-volume air sampler equipped with either cellulose fiber or glass fiber filters. Samples taken from urban environments require approximately 1 h of sampling time, but samples from rural environments require substantially longer times. 

K. D. Racke and A. R. LesHe, eds.. Pesticides in Urban Environments Tate and Significance, ACS Symposium Series No. 522, American Chemical Society, Washington, D.C., 1993, 385 pp. 

The number of particles varies considerably with time and place (Table 9.1). To reduce the number of particles in the urban environment to the same number as in the countryside, a filter with 99.9% separation is required. An... 

A large number of odors are borne by particles, but for effective separation, chemical filters are very often required, which can be justified in an urban environment. 

Many transit trips involve translers between ti ansit vehicles. All else being equal, passengers would prefer not to transfer. However, the mode of access to transit is of interest. The vast majority of transit customers walk to transit and then walk again to their final destination. It is difficult to develop high transit demand in an urban environment that is not conducive to walking. 

Health-related institutions again show the future trend in a microcosm. Suitable incineration facilities may determine the ability of such institutions to function effectively in an urban environment. When adequate processes for solid waste and air pollution control by incineration are developed, the use of combustible, one-way trip disposables for all incoming materials can be expected to accelerate. This will result in a decrease in the need for a direct fuel supply. 

Carbon monoxide (CO) Is one of the most widely distributed air pollutants. It Is formed by natural biological and oxidation processes, the Incomplete combustion of carbon-containing fuels and various Industrial processes. However, the largest Individual source of man-made emissions Is motor vehicle exhausts which account for virtually all CO emitted In some urban environments. It has been estimated that global man-made emissions range from 300-1600 million tons per year, which Is approximately 60% of the total global CO emissions (22-23). 

As seen in Table 12-2, global NO production is dominated by anthropogenic sources. In an urban environment, virtually all NO is from fossil fuel combustion. 

Studies on the particulate distributions from compressed natural gas (CNG) or diesel-fuelled engines with diesel oxidation catalyst (DOC) or partial diesel particle filter (pDPF) have also been performed. The results obtained are used as data for the model, to study the particle penetration into the human respiratory tracts. As a result, the number distribution of particles in different parts of lungs can be modeled [99-101]. Understanding the particle formation and their effects and finding the methods to ehminate the formed particulates from exhaust gas contribute to a cleaner urban environment and thus to a better quality of life. 

Transportation is a major source of air pollution, particularly in urban environments. The total number of cars, trucks, buses and motorcycles in the world in 1990 was estimated at about 650 million. All these vehicles produce exhaust, and an esti-... 

Singh HB, Salas LJ, Smith AJ, et al. 1981. Measurements of some potentially hazardous organic chemicals in urban environments. Atmos Environ 15 601-612. 

Figure 90. Map of the urban environment for the ATES system and a schematic section across the esker. The scale of the map is approx. 1 3,000...

Another major externality that will shape the electricity sector is the environmental impact of energy use at all geographical scales - smog and particulates in urban environments, regional acid rain, global warming. 

In 1982-1983, the baseline value for daily intake of lead by inhalation in a nonurban environment was estimated to be 0.5 pg/day for a 2-year-old child. The baseline value was based on an average atmospheric lead concentration of 0.1 pg/m3 and an indoor/outdoor lead concentration ratio of 0.5. In an urban environment, the indoor/outdoor ratio was assumed to be approximately 0.8 (EPA 1986a). Drastic reductions in the lead content of gasoline since 1986 have resulted in a 64% decrease in lead emissions to the atmosphere (see Section 5.4.1). 

Bomschein RL, Succop PA, Krafft KM, et al. 1986. Exterior surface dust lead, interior house dust lead and childhood lead exposure in an urban environment. In Hemphil DD, ed. Trace substances in environmental health. Vol. 20. Columbia, MO University of Missouri 322-332. 

Early on in the FQPA implementation process, EPA decided to focus on OP insecticide risks. Residues of these insecticides were frequently found in foods consumed by children, these insecticides were widely used in the home and other urban environments and their toxicity was well established. In addition, EPA knew years before the passage of the FQPA that many then-... 

Steinhausler, F., W. Hofmann, E. Pohl, and J. Pohl-Ruling, Local and Temporal Distribution Pattern of Radon and Daughters in an Urban Environment and Determination of Organ Dose Frequency Distributions With Demoscopical Methods, in Proceedings of the Symposium on Natural Radiation Environment. III. Houston. Conf-780422, DOE Sym. Ser. 51, Vol. II, pp. 1145-1161, Houston NM,... 

---