chapter 18 Flashcards
to study for test (dec 4)
atmospheric pressure
- measure of mass per unit of air
- decreases with altitude
density
varies throughout the atmosphere due to gravitational forces
- air at sea level has higher density than air at the top of a mountain
atmosphere
thin layer of gases that surrounds the earth; classified into layers characterised by changes in temperature
- 78% nitrogen
- 21% oxygen
- .9% argon
- .1% water vapour, carbon dioxide, neon, helium, trace gases
troposphere
- earth to 10km up
- 75-80% of atmospheric gases
- short-term weather patterns & long-term climate occurs here
stratosphere
- 10km to 50km above earth
- ozone layer is here; absorbs the majority (95%) of uv radiation from the sun
mesosphere
- 50km to 80km above earth
- colest layer of the atmosphere (as low as -90deg C)
ozone
- bad in the troposphere, good in the stratosphere
- oxygen molecules + uv radiation = o3
thermosphere
- 80km into space
- ionosphere: lower layer, 80km to 550km; reflects radio waves back to earth; cannot reflect shorter tv waves
- exosphere: upper layer, blends into the vacuum of interplanetary space
primary pollutants
pollutants emitted directly into the air
secondary pollutants
formed when primary pollutants react together or with the atmosphere
major air pollutants
- carbon oxides
- nitrogen oxides
- particulaates
- vocs
- ozone
- radon 222, plutonium 239
outdoor air pollution
- comes mostly from natural sources (dust particles, organic chemicals from plant decay, forest fires) and burning fossil fuels (vehicles, industrial plants, urban areas)
- pollution from natural sources rarely reach harmful levels
outdoor primary pollutants (examples)
soot, carbon monoxide, nitric oxides
outdoor secondary pollutants (examples)
nitric acid
indoor air pollutants
come from infiltration of outside air & chemicals used/produced inside buildings
photochemical smog
- nitrogen oxides or vocs + heat and sunlight = pc smog & other pollutants (more than 100)
- some no2 reacts with hydrocarbons to produce a mixture of ozone, nitric acid, aldehydes, PANs, etc.
temperature inversion
when cool air is trapped below warm air
- can prevent outdoor pollutants from rising & dispersing
- dense, colder air becomes stagnant and accumulates more pollutants
- cities in valleys surrounded by mountains & areas with sunny climate, light winds, mountains, and lots of vehicles
- e.g. los angeles basin
industrial smog
- mixture of sulphur dioxide, droplets of sulphuric acid, and suspended solid particles (emitted by burning coal & oil)
reducing outdoor air pollution
- precipitation, sea spray, winds
- heavy particles settle out of the atmosphere due to gravity
- chemical reactions of pollutants
- these methods remove pollutants from the air & deposit them elsewhere
increasing outdoor air pollution
- urban buildings
- mountains
- high temperatures
air pollution control
- catalytic converters
- wet & dry scrubbers
- electrostatic precipitators
- vapour recovery nozzle
- afterburners
catalytic converter
used in automobiles to convert co, NOx, and hydrocarbons to less harmful gases (like co2)
wet & dry scrubbers
gases in smokestacks are passed through CaO (lime) or CaCO3 (calcium carbonate) to remove SO2, accumulating in a sludge
- smokestacks can reduce local pollution, but increase regional pollution
electrostatic precipitators
removes particulates using an induced electrical charge
vapour recovery nozzle
on a gasoline pump, minimises gas fumes from escaping
afterburners
an additional combustion process
acid deposition
- SOx, NOx, and particulates react in the atmosphere to produce acidic chemicals
- these chemicals travel long distances before coming back to earth
- big problem in areas downwind from coal-burning facilities & urban areas
wet vs dry deposition
wet: acidic rain, snow, fog, vapour with pH less than 5,6
dry: adicic particles
sick-building syndrome
- buildings with particularly poor air quality
- caused by tobacco smoke, fromaldehyde, gasoline, radon gas, abestos, CO, VOCs, fungi, bacteria
radon 222
colourless, odourless, radioactive gas
- produced by decay of uranium 238
clean air acts
- epa established naaqs (national ambient air quality standards)
- epa established national emission standards for roxic air pollutants
- 2003 clear skies initiative: reduced the effectiveness of the clean air act
neutralising acid lakes
- adding limestone or lime to water or soil
- adding a small amount of phosphate fertiliser
- reducing SO2, NOx, and particulates
- use of low-sulphur coal (pros and cons)
deficiencies of clean air act
- continued reliance on pollution cleanup vs prevention
- failure to sharply increase fuel efficiency for vehicles
- no strict emission standards for fine particulates
- municipal trash incinerators are given 30-year permits
- weak standards for incinerators
- weak standards for emissions of CO2 and other GHGs
indoor air pollution statistics
- common pollutants are 2-5x greater inside homes & buildings than outside
- inside cars in traffic-clogged areas, the pollution may be 18x higher than outside
- health risks are magnified bc people usually spend 70-98% of their time indoors or in vehicles
- as many as 2.8mil people die prematurely per year from breathing in high levels of indoor smoke & particulates
four most dangerous indoor air pollutants
- cigarette smoke
- formaldehyde
- radioactive radon-222 gas
- small fine & ultrafine particles
formaldehyde
chemical used to manufacture common household materials; taxidermy; vaping
radon-222
found in soils & rocks; can seep into homes & increase risk of lung cancer
- produced by the radioactive decay of U-238
- thought to be 2nd leading cause of lung cancer deaths each year in the usa
remedies: sealing cracks in foundation & walls, increase ventilation, use a fan for cross ventilation
how the respiratory system protects from air pollution
- hairs in the nose filter out large particles; sticky mucus lines the respiratory trap to capture smaller particles & dissolved gases
- sneezing/coughing to expel contaminated air & mucus
disease & dangers from air pollution
- prolonged/acute exposure to air pollutants can break down natural defences
- asthma, lung cancer, chronic bronchitis, emphysema
- people with respiratory diseases, the elderly, infants, pregnant women, and people with heart disease are especially vulnerable
