tailieunhanh - Air Pollution Engineering

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 should not be exceeded, and incorporates a safety factor (NEPC, 1998). Until recently, it was thought that current CO. | 1 Air Pollution Engineering The phenomenon of air pollution involves a sequence of events the generation of pollutants at and their release from a source their transport and transformation in and removal from the atmosphere and their eifects on human beings materials and ecosystems. Because it is generally either economically infeasible or technically impossible to design processes for absolutely zero emissions of air pollutants we seek to control the emissions to a level such that effects are either nonexistent or minimized. We can divide the study of air pollution into three obviously overlapping but somewhat distinct areas 1. The generation and control of air pollutants at their source. This first area involves everything that occurs before the pollutant is released up the stack or out the tailpipe. 2. The transport dispersion chemical transformation in and removal of species from the atmosphere. This second area thus includes all the chemical and physical processes that take place between the point of emission and ultimate removal from the atmosphere. 3. The effects of air pollutants on human beings animals materials vegetation crops and forest and aquatic ecosystems including the measurement of gaseous and particulate species. An air pollution control strategy for a region is a specification of the allowable levels of pollutant emissions from sources. To formulate such a strategy it is necessary to be able to estimate the atmospheric fate of the emissions and thus the ambient concentrations so that these concentrations can be compared with those considered to give 1 2 Air Pollution Engineering Chap. 1 rise to adverse effects. The ultimate mix of control actions and devices employed to achieve the allowable levels might then be decided on an economic basis. Therefore the formulation of an air pollution control strategy for a region involves a critical feedback from area 3 to area 1. Consequently all three of the areas above are important in air pollution .