IndoorAirPollution上海交通大学环境科学与工程学院课件

1、indoorairpollution上海交通大学环境科学与工程学院1indoor air pollutionradioactivity from radon gas group members: 刘佳颖，叶秋雯，裴伟indoorairpollution上海交通大学环境科学与工程学院2outlineintroductionwhere does radon come from?how does radon get inside buildings? the level and distribution of radonthe risk of living with radonreducing ra

2、don risksindoorairpollution上海交通大学环境科学与工程学院3introductionalthough 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 pol

3、lutants is an important environmental problem. indoorairpollution上海交通大学环境科学与工程学院4whats 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, certa

4、in wallboards, carpets, or insulation as well as the geology of the area (radon in soil or rocks beneath the structure). indoorairpollution上海交通大学环境科学与工程学院5whats 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 w

5、ith plumbum (铅). indoorairpollution上海交通大学环境科学与工程学院6uranium-238 decay chain indoorairpollution上海交通大学环境科学与工程学院7indoorairpollution上海交通大学环境科学与工程学院8property of radonsingle atom gasinert, colorless, odorless at ordinary temperaturesmelting point: 202 degrees k boiling point: 211 degrees k atomic radius: 1

6、.34 angstroms (the heaviest known gas)half-life: 3.8daysindoorairpollution上海交通大学环境科学与工程学院9 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.); paintsbuilding mat

7、erials: gypsum board (sheetrock), concrete block, mortar, sheathing paper (tarpaper), wood paneling, and most insulation. indoorairpollution上海交通大学环境科学与工程学院10some uranium is present in all earth materials.on continental surfaces the rocks, sediments and soils typically contain between 1 and 3 parts p

8、er million (abbreviated ppm) of uranium. some earth materials may have more.indoorairpollution上海交通大学环境科学与工程学院11how does radon get inside buildings? indoorairpollution上海交通大学环境科学与工程学院12cracks in solid floors construction joints cracks in wallsgaps in suspended floorsgaps around service pipescavities i

9、nside wallsthe water supplyindoorairpollution上海交通大学环境科学与工程学院13radon 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

10、and interconnected pore spaces that act as conduits for radon).enter the lowest level of a building using whatever pathways are available. soilindoorairpollution上海交通大学环境科学与工程学院14for structures with basements or slab-on-grade foundations, the entry points includecracks and pores in floor slabs, walls

11、, and floor-wall joints; openings around sump pumps, floor drains, and pipes penetrating floors and walls. indoorairpollution上海交通大学环境科学与工程学院15structures with a crawl space between the ground and lowest floor level may be less vulnerable to radon, which tends to escape to the outside air when appropr

12、iate vents are installed, but can still admit some of the gas through cracks in the flooring. indoorairpollution上海交通大学环境科学与工程学院16waterradon can also enter into homes through the water system.this is mainly true for houses in which ground water is used as the main water supply. indoorairpollution上海交通

13、大学环境科学与工程学院17small public water works and private domestic wells often have closed systems and short transit times that do not allow radon to decay to harmless by-products before entering a home. once inside, radon escapes from the water to the indoor air as people take showers, wash clothes or dish

14、es, or otherwise use water. the areas most likely to have problems with radon in ground water are those with have high levels of uranium in the underlying rocks.indoorairpollution上海交通大学环境科学与工程学院18water in rivers and reservoirs usually contains very little radon, because it escapes into the air. thus

15、 homes that rely on surface water usually do not have a radon problem from their water. in big cities, water processing in large municipal systems aerates the water, which allows radon to escape, and also delays the use of water until most of the remaining radon has decayed.indoorairpollution上海交通大学环

16、境科学与工程学院19the average level of radon found in a homebased on a national residential radon survey completed in 1991, the average indoor radon level is about 1.3 picocuries(皮居里=10-12ci) per liter (pci/l) in the united states. the average outdoor level is about 0.4 pci/l.indoorairpollution上海交通大学环境科学与工程

17、学院20the safe level of radon there is no safe level of radon-any exposure poses some risk of cancer. indoorairpollution上海交通大学环境科学与工程学院21zone 1 counties have a predicted average indoor radon screening level greater than 4 pci/l (pico curies per liter) (red zones) zone 2 counties have a predicted avera

18、ge indoor radon screening level between 2 and 4 pci/l (orange zones) zone 3 counties have a predicted average indoor radon screening level less than 2 pci/l (yellow zones) indoorairpollution上海交通大学环境科学与工程学院22the risk of living with radonradon gas decays into radioactive particles that can get trapped

19、 in your lungs when you breathe.as they break down further, these particles release small bursts of energy. this can damage lung tissue and lead to lung cancer over the course of your lifetime.indoorairpollution上海交通大学环境科学与工程学院23smoking combined with radon is an especially serious health risk.childre

20、n have been reported to have greater risk than adults of certain types of cancer from radiation, but there are currently no conclusive data on whether children are at greater risk than adults from radon.indoorairpollution上海交通大学环境科学与工程学院24radon risk if you smoke/never smokeradon levelif 1,000 people

21、who smoked were exposed to this level over a lifetime*.if 1,000 people who never smoked were exposed to this level over a lifetime*.what to do:stop smoking and.20 pci/labout 260 people could get lung cancerabout 36 people could get lung cancerfix your home10 pci/labout 150 people could get lung canc

22、erabout 18 people could get lung cancerfix your home8 pci/labout 120 people could get lung cancerabout 15 people could get lung cancerfix your home4 pci/labout 62 people could get lung cancerabout 7 people could get lung cancerfix your home2 pci/labout 32 people could get lung cancerabout 4 person c

23、ould get lung cancerconsider fixing between 2 and 4 pci/l1.3 pci/labout 20 people could get lung cancerabout 2 people could get lung cancer(reducing radon evels below 2 pci/l is difficult.)0.4 pci/labout 3 people could get lung cancernote: if you are a former smoker, your risk may be lower.* lifetim

24、e risk of lung cancer deaths from epa assessment of risks from radon in homes (epa 402-r-03-003).* comparison data calculated using the centers for disease control and preventions 1999-2001 national center for injury prevention and control reports.indoorairpollution上海交通大学环境科学与工程学院25epa (environmental protection agency 美国环保署) estimates that radon causes thousands of cancer deaths in the u.s. each year.indoorairpollution上海交通大学环境科学与工程学院26reducing radon risks there are two ways to protect yourfamily from radon.first, the