Difficulty: Easy
Correct Answer: 1000
Explanation:
Introduction / Context: Land-use planning and buffer zoning reduce public exposure to accidental releases, routine emissions, and nuisance impacts (noise, odour). Many siting guidelines recommend an exclusion zone—often with a planted green belt—around hazardous or highly polluting chemical facilities.
Given Data / Assumptions:
Concept / Approach: A 1000 m (1 km) exclusion/green belt buffer is a widely referenced planning value in many teaching texts for hazardous installations, providing dispersion distance, visual screening, and land-use separation. While site-specific quantitative risk assessment may refine this distance, the 1 km figure is the canonical single-choice answer.
Step-by-Step Solution:
Identify need for a defensible general value.Recognize 1 km as the commonly taught planning distance for high-hazard sites.Choose 1000 m from the options.Verification / Alternative check: Teaching materials and example siting problems often apply 1 km buffers before more detailed risk-based calculations.
Why Other Options Are Wrong:
100 m / 400 m: Typically too small to ensure effective public separation for major hazard facilities.4000 m: Four kilometres is a large exclusion that exceeds common planning baselines absent special hazards.Common Pitfalls: Treating the buffer as a universal legal requirement; in practice, risk-based, topography, and meteorology-specific evaluations refine distances.
Final Answer: 1000
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