2. Chemistry and the environment

3. Air pollution Some air pollutants 1. Carbon monoxide 2. Oxides of sulphur(SO2 and SO3) 3. Oxides of nitrogen 4. Hydrocarbons 5. Particulates 6. Carbon dioxide

4. What is meant by "ozone hole" ? Concentrations of ozone fell by as much as 50% of the norm at altitude of 18 km. At mid- latitudes in the Northern Hemisphere, up to 3% decrease in ozone concentration was also observed.

5. Why it concerns you? The ozone molecules form a protective layer, which extends from about 16 km to 50 km up above the earth at low latitudes, and from about 8 km to 50 km at high latitudes. The ozone molecules absorb the sun ultra violet radiation (UV), which will be harmful to us if it reaches the earth surface.

6. What causes this phenomenon? These chemicals contain chlorine or bromine atom with inherent chemical stability and have long lifetime in the atmosphere, in the range of 40 to 150 years.

7. How can I help to protect the ozone layer? Buy air-conditioning equipment that does not use CFC as refrigerant. When motor vehicle air-conditioners need servicing, make sure that the CFC refrigerants are properly recovered and recycled instead of being vented to the atmosphere.

8. Water pollution Water pollution are defined as a substance or condition that interferes with our normal use of the water, for whichever purpose we intend.

9. Effects of water pollution on the environment Livestock wastes Oil spillage Residues of pesticide Detergents in sewage Industrial effluents 1. Oil spillage

10. Solid Waste Municipal Solid Waste (MSW) Construction and Demolition (C&D) waste Chemical waste Special wastes (clinical waste, animal carcasses, livestock waste, radioactive waste, grease trap waste and waterworks/sewage sludge)

11. How do we deal with the waste?

12. Here… Chemical Waste Treatment Centre, Chemical Waste Treatment Centre, Strategic landfills X 3 Strategic landfills X 3 A network of refuse transfer stations A network of refuse transfer stations Waste reduction Waste reduction

13. There are two places in HK to collect our waste~ The Chemical Waste Treatment Centre on Tsing Yi Island (1993) The Chemical Waste Treatment Centre on Tsing Yi Island (1993) The Sha Ling Composting Plant in the northern New Territories (1991) The Sha Ling Composting Plant in the northern New Territories (1991)

14. How about the water pollution?

15. The government has a three- pronged approach for dealing with the problem: controlling pollution at source, providing sewers collecting and treating sewage.

16. Sewage charges Domestic Households rate of $1.20 per cubic meter of water cnsumed with exemption for the first 12 cubic meters, in a four-month billing period. Trade, Business and Manufacture The charges include a Trade Effluent Surcharge (TES) payable by thirty specific trades and a Sewage Charge (SC): (i) the SC is at a prescribed rate of $1.20 per cubic meter of water supplied (ii) TES = the volume of water supplied, multiplied by the appropriate rate specified in Schedule 1 of the Sewage Services (Trade Effluent Surcharge) Regulation. (iii) the volume of water used in the calculation of charges is reduced for certain categories of trade, business and manufacture which discharge less water than they are supplied with.