Air Pollution
Outline • Classification • Composition of air • Sources of air pollution • Effects • Controls • Major air pollution problems • Air policy and Legislation • Air Pollution Index (API)
Types of air pollution • Personal air pollution • Occupational pollution • Community / environmental air pollution
Sources • Natural • Man-made
Natural • Wind-blow dust • Smoke • Gases from swamp • Fog • volcanic
Natural Pollutants • SO2 • H2S • CO • NO,NO2 • NH3 • Hydrocarbon • CH4 • CO2 • O3
Man-made • Dust • Combustion • Manufacturing • Agricultural • Nuclear energy
Man-made Pollutants • Particulates • Oxides of sulphur and nitrogen • CO2 • Organic vapour • Vapour with traces of heavy metal • H2S • Radioactive
Effects • Vegetation • Human beings and animals • Materials • Health
Materials • Abrasion • Deposition • Chemical attack • Corrosion
Health • Particulates – respiratory tracts • SO2 – respiratory, asthematic • CO2, CO - • No2 - respiratory • O3 - respiratory • Pb – nervous and cardiovascular
Control • Zoning • Control at source • Use device and equipment • Use high stacks • vegetation
Zoning
Control at source • Replace • Reengineering • Redesign • Reduce
By device • Gravitational settling chamber • Inertial collectors • Wet collectors • Fabric • Electrostatic precipitators
Control at construction site • Legislation • Dust reduction measures • Stop malpractice • Notify Environmental Protection Dept
Dust reduction measures • Wet by water spray • Provide hoarding to fence off the site • Product dust screen • Cover dusty materials on site and vehicles • Dispose dusty materials correctly • Cover unfinished site formation work • Provide vehicle wash basin
Stop malpractice • Do not use compress air for cleaning • Do not operate without any controls • Do not stockpile dusty materials without proper procedures • Do not blast on strong wind signals
Notify EPD • Site formation • Reclamation • Building demolition • Tunnel work • Building construction • Road construction
Major Problems Acid Rain Ozone depletion Green House Effect Indoor Air Pollution
Acid Rain • pH as low as 3 • Mainly due to Industrial pollutants • No2, So2 and volatile organic vapour are converted to acidic compounds
Effects of Acid Rain • Natural life • Building materials • Crops and vegetation • Cause deteriation of soil
Ozone depletion • Ozone exist in stratosphere (outer atmosphere) • Ozone is used to shield ultra-violet light (short-wave length) • Ozone is depleted by CFC (carbo-halogen-compound) • Nitrous oxide contribute to depletion of ozone
Effects of Ozone depletion • Skin cancer • Eye sickness • Kill phytoplankton • Decrease in food supplies • More CO2
Green House Effects • Absorb long-wave (ultra-red) • Let in short-wave and absorb long wave • Acts like a glass in a green house • Cause global warmness
Effects of Green house • Rise of water temperature and causing global climate changes
Indoor Air Pollution • CO • Formaldehyde • Radon • NO2
Effects of indoor air quality • Sick building syndrome
Control
Control • Land use planning • Enforcement of Air Pollution Ordinance • AQO • Restrict certain specified process/trades
Hong Kong Air Quality Objective • SO2 • TSP • RSP • NO2 • CO • Ozone • Lead
AQO • Exposure in hours • Exposure quantity
Air Pollution Index
What is API ? • The API is an index that converts several pollutants into a value ranging from 0 – 500 • API forecast serves as a warning to the public
How is it determined • It is calculated by comparing the measured concentration of major air pollutants with their respective health related AQO. • These pollutants are NO2, SO2, ozone, CO, and RSP. • APIs for each of these pollutants are calculated and the highest API number is reported. • API’s are reported hourly.
How to use APIs ? • The API values are divided into 5 bands. • We can relate API to the followings • Air Quality status • Air Pollution level • Health implication • Actions recommended
Locations of monitoring
Roadside API
