HAZE POLLUTION

The above quotation from the 19 century travel book (Brassey, 1889) is a direct reference to Brunei Bay and Brunei River, and it demonstrates that forest fires and the associated smoke pollution have been taking place during the whole period of forest clearing in this area. This natural event is enhanced by anthropogenic activities and many effects on human health and ecosystem behavior have been recorded. 

In this chapter we will consider the geographical distribution of recent forest fires in Southeast Asia, chemical composition of haze and synergetic effects of haze pollutants and anthropogenic air contaminants on human health. 

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An extensive source of natural pollutants is the plants and trees of the earth. Even though these green plants play a large part in the conversion of carbon dioxide to oxygen through photosynthesis, they are still the major source of hydrocarbons on the planet. The familiar blue haze over forested areas is nearly all from the atmospheric reactions of the volatile organics... 

Smog a mixture of air pollutants, principally ground-level ozone, produced by chemical reactions involving smog-forming chemicals. See also haze. 

Aerosol particles - the visible haze in polluted air - reflect and absorb sunlight, directly influencing the heat balance over large (>1000 km)... 

On a worldwide basis, toxic concentrations of the heavy metals have thus far been limited to industrialized harbors. The only metals that appear to have accumulated to toxic levels on a regional scale are mercury, cadmium, and lead in the Arctic Ocean. This concentration of mercury and lead has been fecilitated by a natural process, called the grasshopper effect, which acts to transport volatile compoimds poleward. This transport plays a major role in redistributing the volatile organic pollutants, such as the PCBs, and, hence, is discussed at further length in Chapter 26.7. The process responsible for the cadmium enrichment in the Arctic appears to involve low-altitude transport of the fine particles that compose Arctic haze. 

Three properties of photochemical smog were evident first in Los Angeles eye irritation haze (aerosol) formation and the d adation of rubber products. All three are associated with oxidants, although aerosols can also be formed by other pollutants, particularly sulfur dioxide. 

Many deleterious effects have been associated with photochemically polluted air ozone is deflnitely associated with respiratory problems, plant damage, and material damage PAN has deflnitely been associated with plant damage, and some other members of this class of chemical compounds have been associated with eye irritation the hydroxyl radical is considered to be an important factor in the conversion of gas-phase intermediates to end products, such as sulfur dioxide to particulate sulfate the particulate complex is responsible for haze formation and has also been associated with eye irritation and respiratory effects. The aldehydes have been associated with eye irritation. Ozone and PAN themselves do not cause eye irritation. For purposes of control, much more research is needed, in order to relate the laboratory data about the concentrations of these various materials that have significant effects to their formation in the atmosphere from emission and their atmospheric distribution. The lack of convenient measurement methods has hindered progress in gaining this understanding. 

Methods for the direct and continual measurement of chemicals in the particles of the atmospheric haze that are known to be formed during photochemical-pollution episodes and are already suspect as respiratory irritants . By implementing such measurements, it will be possible to find out to what extent the occurrence of such substances can be reduced by various emission controls. To assess actual population expo-... 

SO3 control is also an increasingly important issue for refinery FCC operators. Regional haze, PMj 5, hazardous air pollutants, and visible stack emissions all in some way relate to SO3. The present level of control achievable in wet scrubbers is limited. However, use of wet ESPs integral to the scrubber has been used commercially. 

Ambient aerosols, particularly those with diameters less than 3pm, are a serious pollution problem. Carbonaceous material is a major component of the fine particle concentration (10 and has undergone extensive study in the past few years (, ) in large part because of the concern that these particles play an Important role in urban haze and community health. 

Ferrnan, M. A., G. T. Wolff, and N. A. Kelly, The Nature and Sources of Haze in the Shenandoah Valley Blue Ridge Mountains Area, J. Air Pollut, Control Assoc., 31, 1074-1082 (1981). 

Other important inputs to AQM are the transformation and deposition processes of air pollutants. Examples of air quality modeling where transformation and deposition processes need to be considered are acid deposition, regional haze, and photo-oxidants. 

Fig. 2. Regional haze in the Vermont Green Mountains. Note as the pollution episode progresses, adjacent peaks are no longer visible. (Photo by the Vermont Agency of Environmental Cbnservatioa)...

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