Lecture 8 - Air Pollution Flashcards
Primary vs. secondary pollutants
Primary: pollutants emitted into the environment in a form that can be directly harmful, or that can react to form harmful substances.
Secondary pollutants: harmful substances formed when primary pollutants react with constituents of the environment (often atmosphere).
Example of secondary pollutant
- Ozone and sulfur trioxide
Point vs. non-point sources of outdoor air pollution
Point Sources: emanates from a discrete location
Non-point Sources: emanates from diffuse points, many sources.
What is the CEPA 1999 and why is it important?
Created to regulate the production and use of toxic substances.
Goals:
- reduce pollution
- protect the environment
- protect human health
CEPA covers the following air pollutants:
1. Criteria air contaminants
2. POPs
3. Heavy metals
4. Toxic air pollutants
What are criteria air contaminants, with examples
Pollutants for which maximum allowable concentrations have been established
- Sulfur dioxide (SO2)
- smelly, colorless gas
- produced primarily from fossil fuel combustion - Nitrogen dioxide (NO2)
- smelly red-brown gas; contribute to smog and acid precipitation
- combustion engines primarily - Particulate matter
- tiny solid or liquid particles
- from combustion, dust - Volatile Organic Compounds (VOCs)
- carbon compounds that are volatile, wide range
- household chemicals, engine combustion, solvents, industrial processes - Carbon monoxide (CO)
- colorless, odorless gas
- combustion of fuel; mostly vehicles, also industry, waste combustion, wood combustion - Ammonia (NH3)
- colorless gas that smells awful
- livestock waste, fertilizer production; can combine with sulfates and nitrates - Tropospheric Ozone (O3)
- colorless gas, smells slightly sweet
- secondary pollutant, created from the interaction btw sunlight, heat, nitrogen oxides, and carbon compounds
- O3 is a pollutant when in the troposphere (it is good in the stratosphere)
What are POPs, with examples
Organic compounds RESISTANT TO DEGRADATION/DECOMPOSITION via biological, chemicals, and photolytic (light) processes
- also volatile
- primarily come from anthropogenic sources
- human exposure to POPs is primarily via food
- Pesticides
- Industrial chemicals
- By-products
What are heavy metals
Heavy metals of concern: mercury and lead
Problems:
- associated with particulate matter, easily transported in the atmosphere
- toxic, even in low concentrations
- can bioaccumulate
What are toxic air pollutants, with examples
“Other” stuff that doesn’t fit into the categories of criteria air contaminants, POPs, or heavy metals
- Asbestos
- Chlorofluorocarbons (CFC’s)
- Methyl bromide
Smog
Mixture of air pollutants that form primarily over urban areas
Industrial smog: primary and secondary pollutants
Industrial Smog: produced from the incomplete combustion of coal or oil
Primary: CO2, CO, SO2
Secondary: SO3, H2SO4, (NH4)2SO4
Photochemical smog: primary and secondary pollutants
Photochemical smog: produced from light-driven rxns btw pollutants and atmospheric components
Primary: NO, NO2, VOCs
Secondary: HNO3, O3, PANs
Air Quality Health Index: what is it and what’s included
Metric of air quality developed by the Government of Canada. Calculated based on relative risks of common air pollutants:
- Ozone at ground level (tropospheric ozone)
- Particulate Matter
- Nitrogen Dioxide (NO2)
General health impacts on humans and wildlife
- Respiratory disease and circulatory complications
Global distillation effect
Works via the simple principal that warm air will rise and cool air will fall:
1. at the equator warm air rises into the atmosphere before cooling and falling back closer to the poles
2. as the air rises it will take with it semi volatile compound which have evaporated at the warm temps
3. upon reaching the poles, cool temperature result in condensation and precipitation in the form of snow
Pollutants in the troposphere and stratosphere
Troposphere:
- natural and anthropogenic emissions: CH4, CO, CO2, VOCs, Sulfate, Black Carbon, Dust, N2O, CFCs, NOx, O3
Stratosphere:
- CFCs
