6 - Air pollution Flashcards
What is a primary pollutant?
Pollutants emitted into the environment in a form that can be directly harmful, or that can react to form harmful substances
What is a secondary pollutant
Harmful substances formed when primary pollutants react with constituents of the environment (often atmosphere)
Example of a primary pollutant and some of its secondary pollutants
Primary = nitrogen dioxide
Can react with water to form nitric acid (acid rain)
Reacts with molecular oxygen to form ozone
Reacts with atomic oxygen and hydrocarbons to form aldehydes
Sequence of layers of the atmosphere from innermost to outermost
Troposphere, stratosphere, mesosphere, thermosphere, exosphere
Two types of air pollutant sources
Point sources: emanates from a discrete location (buildings, factories, mines)
Non-point sources: emanates from diffuse points, many sources (e.g. cars, planes)
What is CEPA? Goals?
Canadian Environmental Protection Act
Created in 1999 implemented in 2000 to regulate the production and use of toxic substances
Goals:
- reduce pollution
- protect the environment
- protect human health
What does CEPA cover for air pollutants?
- criteria air contaminants (pollutants for which maximum allowable concentrations have been established)
- persistent organic pollutants (POPs)
- heavy metals (highly dense metals, toxic in low conc)
- toxic air pollutants (all others, e.g. asbestos, CFCs)
Name the criteria air contaminants
- sulfur dioxide (SO2)
- nitrogen dioxide (NO2)
- particulate matter (PM)
- volatile organic compounds (VOCs)
- carbon monoxide (CO)
- ammonia (NH3)
- tropospheric ozone (O3)
What is sulfur dioxide? How is it produced?
Smelly colorless gas
Produced primarily from fossil fuel combustion
What is nitrogen dioxide? How is it produced?
Smelly red-brown gas. Contributes to smog and acid precipitation (reacts w H2O)
Combustion engines
What is particulate matter? Forms? How is it produced
Tiny solid or liquid particles
PM10 = particles <10 um
PM2.5 = particles <2.5 um
Produced through combustion, dust
What are volatile organic compounds? How are they produced
Carbon compounds that are volatile (evaporate), have low water solubility. Wide range
Household chemicals, engine combustion, solvents, industrial processes
Examples of building materials, home and personal care products and activities that have/produce VOCs
Paint, varnishes, carpet
Air fresheners, cleaning products, gasoline, cosmetics
Smoking, cooking, burning wood
What is carbon monoxide? What can it cause? How is it produced?
Colorless, odorless gas
Exposure to high concentrations leads to red blood cell dysfunction and death by asphyxiation
Combustion of fuel. Mostly vehicles, also industry, waste combustion, and wood combustion
What is ammonia? How is it produced
Colorless gas that smells awful (like urine)
Livestock waste, fertilizer production. Can combine with sulfates and nitrates to create PM2.5