Ambient air

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  • Because of the potential public health implications, the importance of toxic air pollutants in ambient air has been recognized to some degree for many years. Efforts to “regulate” human activities resulting in the production of ambient air pollutants probably date back many centuries, even as the combustion of fossil fuels and air pollution from other organized human activities began having a noticeable impact on the environment.

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  • The atmosphere may be our most precious resource. Accordingly, the balance between its use and protection is a high priority for our civilization. While many of us would consider air pollution to be an issue that the modern world has resolved to a greater extent, it still appears to have considerable influence on the global environment. In many countries with ambitious economic growth targets the acceptable levels of air pollution have been transgressed. Serious respiratory disease related problems have been identified with both indoor and outdoor pollution throughout the world....

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  • Human beings need to breathe oxygen diluted in certain quantity of inert gas for living. In the atmosphere, there is a gas mixture of, mainly, oxygen and nitrogen, in appropriate proportions. However, the air also contains other gases, vapours and aerosols that humans incorporate when breathing and whose composition and concentration vary spatially. Some of these are physiologically inert. Air pollution has become a problem of major concern in the last few decades as it has caused negative effects on human health, nature and properties....

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  • Tham khảo sách 'air quality monitoring, assessment and management_1', khoa học tự nhiên, công nghệ môi trường phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả

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  • Fossil fuel combustion for transportation contributes to air pollution, and air pollution degrades human health. However, the path from transportation to human health costs is anything but straightforward. Which pollutants are produced in which proportions depend on a number of factors, including the vehicle and fuel used and the driving conditions of a particular trip. These emissions are dispersed into the ambient air according to atmospheric conditions, which also influence the extent to which they react to form secondary pollutants.

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  • NGUY HẠI AIR chất gây ô nhiễm: đa dạng và nguồn gốc 188 hóa chất tạo thành HAPs Tiêu đề III là một bộ sưu tập đáng kể đa dạng của các hoá chất cá nhân và các nhóm hợp chất chung chung, và bao gồm các hóa chất công nghiệp và trung gian, thuốc trừ sâu, clo và các dung môi hydrocarbon, kim loại, các sản phẩm phụ đốt cháy, các nhóm hóa học như biphenyl đã polyclo hóa (PCBs), và các hóa chất hỗn hợp như phát thải lò than cốc. ...

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  • Paso del Norte’s growth has had serious environmental consequences, particularly for air quality, which is the worst on the U.S.–Mexico border. Ciudad Juárez exceeds national ambient air quality standards (official norms) for ozone, carbon monoxide, and particulate matter less than 10 microns in diameter (PM10), and El Paso exceeds national ambient air quality standards for ozone, PM10, and carbon monoxide. An overwhelming body of evidence links such air pollution to respiratory and cardiovascular disease, and to premature mortality (U.S. EPA 1999).

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  • Epidemiological studies indicate that NO2 may increase respiratory illness in older children (5–15 years). These findings are of concern because of the potential long-term effects. Studies indicate that repeated respiratory illness in older children (independent of NO2) is associated with increased lung damage in later life. Thus, any increases in such illnesses associated with NO2 could have subsequent, as well as immediate, consequences (WHO, 2000).

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  • Carbon monoxide is a clear, odourless gas produced by the incomplete combustion of organic compounds. It reduces the blood’s capacity to carry oxygen. CO combines selectively with haemoglobin (the oxygen transport protein in red blood cells) to form carboxyhaemoglobin. CO impairs perception and judgment at low levels. Effects worsen as CO levels rise, leading ultimately to convulsions and coma at high concentrations. The CO provisions of the ambient air NEPM are based on evidence that a carboxyhaemoglobin threshold of 2.

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  • Whereas U.S. cities have seen dramatic improvements in air quality over the last three decades1, Mexico City has been considerably less successful. Levels of major air pollutants in Mexico City routinely exceed maximum exposure limits established by the World Health Organization (WHO). For example, the WHO has warned that eight-hour average ozone levels exceeding 100 micrograms per cubic meter threaten human health. 2 During the period 1986-2005, this guideline was exceeded in Mexico City for 92% of all days. A large literature documents the social cost of air pollution (e.g.

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  • The air pollution accumulating in the interior of automobiles consists almost exclusively of gaso- line and diesel exhaust. This toxic soup of gases, aerosols, and microscopic particles includes ben- zene (a known carcinogen), carbon monoxide (which interferes with the blood’s ability to trans- port oxygen), particulate matter (which studies have associated with increased death rates), and a host of other hazardous chemicals.

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  • After its emission or secondary formation, the length of time airborne matter will remain suspended in the air will depend upon its density, shape and size and meteorological conditions. Suspended particles are deposited by dry deposition, either by sedimentation and gravitational settling or impaction due to atmospheric turbulence and diffusion. This latter process is characteristic of particles which undergo Brownian movement and sizes below 0.1µm.

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  • In addition, the distributions of deaths by age and by cause in Delhi are very different from those in the U.S. In the U.S., over 70 percent of all deaths occur after the age of 65. In Delhi, over 70 percent of all deaths occur before the age of 65, with over 20 percent occurring before the age of five. Furthermore, 46 percent of all non-trauma deaths in the U.S. are attributable to cardiovascular disease compared to only 23 percent in Delhi.' Because the main effects of acute exposure to air pollution on daily deaths occur through impacts on...

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  • Epidemiological studies usually report the associations between one or more pollutants and health. However, pollutants such as PM, NO2 (nitrogen dioxide) and CO are often strongly correlated and occur as components of the complex urban air pollution mix. This correlation makes it difficult to accurately determine the independent effects of specific pollutants.

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  • Accordingly, for the purpose of impact assessment, it was decided not to use response functions from daily mortality time-series studies to estimate the excess annual mortality but the change in the long-term mortality rates associated with ambient air pollution. 5 Contrary to the exposure function which is assumed to be the same for all countries, the health outcome frequency (frequency with which a health outcome appears in the population for a defined time span) may differ across countries. These differences may result from a different age structure or from other factors (i.e.

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  • In Austria, particulate matter is measured in agreement with national legislation as Total Suspended Particulate (TSP) at more than 110 sites, whereas PM10 measurements are not yet available. It was assumed that ambient air TSP levels can be attributed to the contribution of local sources and regional background concentrations. Both of them were modelled separately. The starting point for the modelling of local contributions was the availability of a spatially disaggregated emission inventory for nitrogen oxides (NOx).

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  • Health scientists probably know more about the effects of ozone on human health than about any other pollutants. This is because ozone is pervasive in the environment. Also there are excellent methods of measuring ozone so the pollutant can be studied using epidemiological methods. The findings of these epidemiological studies can be verified using well-controlled laboratory studies with human volunteers and laboratory animals.

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  • In 1996, the U.S. Department of Energy (DOE) and Mexico s Petr leos Mexicanos (PEMEX) began sponsoring this project to characterize the nature and sources of suspended particulate matter found in the ambient air in Mexico City. This collaborative effort follows another program sponsored by DOE and PEMEX in the early 1990 s to study gas phase pollutants and photochemical oxidants in the Valle de Mexico. 3,4 The high altitude, the year- round sunshine, and the complex atmospheric chemistry characteristic of Mexico City create a challenging laboratory for scientific research.

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  • Air pollution was on an unsustainable track causing photochemical smog and acid depositions, along with health disasters and increased mortality. Indicators, such as acid and sulfate depositions, ambient levels of pollutants, and asthma hospitalizations, that show the current track are decreasing but are still at detrimental levels. Chapter 21 provides knowledge of air pollution.

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  • Amidst the many advantages of gas turbine (GT) combined cycles (CC) popular today from various standpoints (lower investment than for new greenfield plants, reduced environmental impact, and faster installation and startup), one drawback is that the achievable output decreases significantly as the ambient inlet air temperature increases. The lower density of warm air reduces mass flow through the GT. And, unfortunately, hot weather typically corresponds to peak power loads in many areas. So the need to meet peak-load and power-sales contract requirements causes many ...

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