IndoorAirPollution-上海交通大学环境科学及工程学院

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Introduction
Although pollutant concentrations vary significantly from building to building, the levels of some common air pollutants often are greater indoors than outdoors. Since most people spend more time indoors than outdoors, exposure to indoor air pollutants is an important environmental problctivity from Radon Gas
Group members: 刘佳颖，叶秋雯，裴伟
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Outline
Introduction Where does radon come from? How does radon get inside buildings? The level and distribution of radon The Risk of Living With Radon Reducing Radon Risks
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How does radon get inside buildings?
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Cavities inside walls
Gaps around service pipes
Cracks in solid floors Construction joints
The water supply Gaps in suspended floors
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Where does radon come from?
Natural source:
Earth and rock beneath home; Well water; Outdoor air;
Artificial source:
Daily life materials: leather; low density plastic (like plastic bags, etc.); paints Building materials: gypsum board (sheetrock), concrete block, mortar, sheathing paper (tarpaper), wood paneling, and most insulation.
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Some uranium is present in all earth materials. On continental surfaces the rocks, sediments and soils typically contain between 1 and 3 parts per million (abbreviated ppm) of uranium. Some earth materials may have more.
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For structures with basements or slab-on-grade foundations, the entry points include
Cracks in walls
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Soil
Radon from soil gas is the main cause of radon problems. How much of radon reaches the surface depends on the uranium content of the underlying earth materials together with their depth and permeability (that is, the presence of fractures and interconnected pore spaces that act as conduits for radon). Enter the lowest level of a building using whatever pathways are available.
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What’s radon(氡)?
Radon is a naturally-occurring radioactive(放 射性的) but inert(惰性的) gas part of the decay chain that starts with uranium(铀) and ends with plumbum (铅).
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What’s indoor air pollution?
Indoor Air Pollution is the term used to describe the amount of contaminants in the air inside a building from sources such as cigarette smoking, fuel combustion for heating or cooking, certain wallboards, carpets, or insulation as well as the geology of the area (radon in soil or rocks beneath the structure).
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Uranium-238 Decay Chain
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Property of Radon
Single atom gas Inert, colorless, odorless at ordinary temperatures Melting point: 202 degrees K Boiling point: 211 degrees K Atomic radius: 1.34 angstroms (the heaviest known gas) Half-life: 3.8days