Air Pollution Flashcards
Air Pollutants
Dust/particulates, Oxides of Nitrogen, Tropospheric ozone, Hydrocarbon vapours, PANs, Oxides of Sulphur, Carbon Monoxide. Greenhouse gases also air pollutants even though they are not studied as part of Pollution and should be considered in longer answer questions
Factors affecting the dispersal of atmospheric pollutants
Wind velocity, wind direction, temperature inversions, presence of light/UV, precipitation
Sources of particulate pollution
Combustion of coal and diesel (oil), combustion of wood, crop waste, forest fires, heather moorland, burning of other waste
Size of particulates
PM stands for particulate matter, PM10 - less than 10 microns, PM5 - less than 5 microns, PM1 - less than 1 micron. Smaller particle sizes remain airborne for longer and are more likely to be inhaled.
Effects of particulate pollution on people
Worsening and new respiratory issues (asthma, bronchitis, lung cancer), damage to cilia therefore increased infection
Effects of particulate pollution on other living things
Particulates block light and reduce photosynthesis. Particulates may also contain other toxins such as heavy metals and acids
Effects of particulate pollution on non living things
Adsorption of particulates to buildings, discoloration. Damage to buildings due to acids often present with particulates in particular to limestone structures.
Effects of particulate pollution on climate
Increased albedo by particulates in the atmosphere reduces absorption of solar energy at Earth’s surface leading to global cooling
Effects of particulate pollution on ozone in the stratosphere
Particulates in the atmosphere contribute to ozone depletion by acting as surfaces for chemical reactions that break down ozone molecules.
Smoke smog
Atmospheric pollution event involving smoke and fog
Controls of particulate pollution
Diesel Particulate Filters, coal pretreatment, Improved combustion efficiency, Turbo chargers, Bag filter, Clean Air Act (1956), Cyclone separator, Electrostatic precipitator, Scrubbers
Diesel Particulate Filters
Fitted to the exhaust pipe of diesel engines, traps up to 80% of smoke particulates caused by diesel combustion
Coal pretreatment (for particulates)
Heating coal before combustion to drain off tar to produce smokeless coal.
Turbo chargers
Enables more air (oxygen) to be delivered to the combustion chamber to increase the efficiency of combustion and reduce organic particulates
Bag filter
A method reducing smoke and particulate matter by trapping particulates in fabric filters
Clean Air Act (1956)
UK legislation to control smoke pollution by the establishment of Smoke Zones by making Control Orders in large urban areas.
Cyclone separator
Remove suspended particles from gaseous effluents. Air rotates in a cylindrical chamber which throws suspended particulates to outside surfaces where they fall and collect before the gas is discharged to the atmosphere.
Electrostatic precipitator
Equipment used to remove suspended particles from gaseous effluents by attracting them to electrically charged wires or plates, where they fall and are collected as fly ash.
Scrubber
use of a fine water spray to wash particulates from the air, also used to remove soluble gas pollutants.
Photochemical smogs
Atmospheric pollution events in which primary pollutants such as hydrocarbons, NOx and (secondary) tropospheric ozone interact to produce more toxic secondary pollutants such as PANs (peroxyacetyl nitrates).
Sources of photochemical smogs
NOx from high temperature vehicle combustion engines, O3 produced from the breakdown of NOx by UV, Hydrocarbons from unburnt fuel and fuel stations
Effects of photochemical smogs
NOx and O3 cause respiratory problems on their own however PANs become toxic at very low concentrations and cause eye irritation, breathing difficulties, asthma, emphysema, bronchitis and heart disease
Controls of photochemical smogs
Catalytic convertors to control NOx, Control of hydrocarbon vapours at fuel stations. Low emission zones, tax incentives and grants for electric cars.
Acid precipitation
Any precipitation that is more acidic than pH 5.6. Remember rainwater is naturally acidic due to the reaction of CO2 with water producing carbonic acid. Acid rain usually involves other stronger acids.