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| Block 8: Environmental Issues and Public Health - Air Pollution Chapter 12: Air Quality Management, the Environmental Impact Assessment, Life Cycle Assessment |
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The Standards are in principle based on protecting human health against the adverse effects of air pollution. They are, in principle, set at a level that protect the general population, including the more vulnerable groups such as the elderly, the very young and sensitive groups such as asthmatics. But this statement only applies to pollutants that appear to show a ‘threshold effect’ – a concentration below which adverse health effects are not observed. However, even in the cases where these thresholds are thought to exist, health based standards do not protect exceptionally sensitive individuals, nor do they account for simultaneous exposures to a combination of pollutants.
In the case of substances, including carcinogens, for which no thresholds exist, health based standards have to be set on the basis of the risk of contracting the disease or of suffering the adverse health effect. The question then arises as to the level of "acceptable risk", including the question as to the process for deciding the level of "acceptable risk". (Typically, 1 in million or 1 in 100 000 excess cancers for a lifetime exposure are defined as "acceptable".)
The concept of "health and well-being" should surely include a consideration of the psychological impact of being subjected to odorous substances. It is possible to set ambient air quality standards for odourous substances such as hydrogen sulphide based on the odour threshold.
Persistent pollutants such as dioxins, polycyclic aromatic hydrocarbons (PAHs) and lead compounds present special problems. Natural processes do not break down lead compounds, and break down dioxins and PAHs only very slowly. These compounds therefore tend to accumulate and concentrate in living organisms, and are toxic at very low concentrations in the body. Thus, although contamination of the environment occurs through air pollution, the major health concern is not direct inhalation of these persistent toxins but ingestion through dust and food, and accumulation in the body over time. Ambient air monitoring, although an important tool in monitoring exposure, is only an indirect method of assessing exposure. A multi-pathway exposure assessment is required to assess the impact of air polluted by these substances. The identification, control and elimination of the sources of Persistent Toxic Substance
The NEMA definition of the "environment" is:
"Environment" means the surroundings within which humans exist and that are made up of:
(i) the land, water and atmosphere of the earth;
(ii) micro-organisms, plant and animal life;
(iii) any part or combination of (i) and (ii) and the interrelationships among and between them; and
(iv) the physical, chemical, aesthetic and cultural properties and conditions of the foregoing that influence human health and well-being.
An Environmental Impact Assessment (EIA) is defined (in the EIA guidelines) as -
a process of examining the environmental effects of a development.
In the context of the NEMA definition of the "environment", an EIA must include an evaluation of the likely human health impacts of a development. While the regulations and the guidelines prescribe a set of procedures, including a public participation process, for carrying out an EIA, the scientific methodology to be used is described either in very broad terms or not at all. The decision criteria are also described in broad terms (for example, an impact may be describes as "low" "medium" or "high" without objective criteria for the categorization. The method used in an EIA and the interpretation of the results of an EIA may therefore be open to dispute by contending parties.
A wide range of developmental activities (examples: the construction of a coastal road through the Wild Coast, an expansion of an oil refinery, construction of a waste incinerator, construction of a new shopping center) may have an impact on the environment (as defined). EIA procedures may therefore be complex, and may include a series of ‘specialist studies’ such as an analysis of future traffic patterns, air pollution dispersion modeling studies, health impact assessments or specialist studies of impacts on local fauna and flora.
An EIA in practice tends to examine the relatively local impacts of the proposed activity. A life cycle assessment is a systematic procedure for examining not only the proposed development activity but the potential impact of the product itself throughout the lifespan of the project, and of the impact of the raw materials used in the process, the energy consumption and its use of resources such as water and land. For example, an environmental impact assessment of a coal mine might examine the impact of air and water pollution during operations whereas a life cycle assessment would include an assessment of rehabilitation of the site at the end of the life of the mine, the energy consumed during the mining process itself, and the long term impact of disturbance of the underground water resources. In the case of the manufacture of consumer products, a life cycle assessment would include an assessment of the impacts of the transport system and energy used in the distribution of the product, the waste disposal problem posed by the product after use, the feasibility of recycling materials and the environmental risks posed by the product itself.