10 gaseous pollutants I Flashcards
what are we going to discuss in lectures 10 and 11?
-status or air pollution on human health (impact of air pollution)
-major types of air pollutants
-primary air pollutants: sources and toxicity
-secondary air pollutants: sources, environmental processes, toxicity
-air quality regulations
what are the health consequences of air pollution in canada?
according to health canada report released in 2021, air pollution:
-causes 15,400 premature deaths per year
-10,000 deaths due to chronic PM2.5 exposure (8% of all nonaccidental death of people >25 yrs)
-1,300 deaths due to acute NO2 exposure
-2,800 deaths due to acute O3 exposure
-economic cost of hospitalization, emergency room and doctor’s office visits: 114 billion CAD in 2016
what are major types of air pollutants?
-gaseous
-particulates
-droplets or mist
-smog
-CO2 isnt characterized as an air pollutant
what is the gaseous type of air pollutants?
-inorganic (e.g. SO2, NOx species, CO, O3)
-volatile organic compounds or VOCs (e.g. hydrocarbons, halogenated compounds)
what is the particulate type of air pollutants?
-particles (0.01-100 um in diameter)
-other gases and liquids will absorbed to particulates
what is the droplets or mist type of air pollutants?
-small liquid droplets (1.0-2.0 um) will remain suspended in air
-other gases or liquids will dissolved in droplets
what is the smog type of air pollutants?
-combination of smoke and fog (gases and particulates)
-brown or yellow haze in big cities
what are some important physical processes in air pollution?
-volatilization
-advection
-deposition
cold precipitation
what is volatilization?
-from water, soil and other surfaces or produced directly
-may adhere/dissolved into particulate/droplet
what is advection?
-vapor, particulates or droplets quickly borne away by air currents
-transported great distances if carried into higher atmosphere
what is deposition?
dry
-particulate settling on land/water due to gravitational pull
-most particulates are charged -aggregation
-likely greater contributor than wet, even in damp conditions
wet
-dissolved pollutant carried to earth via liquid droplets (e.g. rain or dew)
what is cold precipitation?
-vapour form of volatile pollutant precipitates as liquid/solid (in absence of water or particulate) and falls to earth because of colder temperatures
-occurs mainly at higher latitude, and/or higher altitude
what are the two categories (types) of air pollutants?
-primary air pollutants: harmful chemicals that enter directly into the atmosphere
-secondary air pollutants: harmful chemicals that result from chemical interactions of primary pollutant or primary pollutants reacting with other compounds normally found in atmosphere
what is sulfur dioxide? what are the sources and toxicity?
sulfur dioxide (SO2) is a primary air pollutant
-anthropogenic source: combustion of fossil fuels, smelting of mineral ores
toxicity
-plants: affects photosynthesis, transpiration, and respiration
-humans: chronic lung diseases such as broncho-constriction, pulmonary edema
what are nitrogen oxides? sources? toxicity?
NO, NO2 which are primary air pollutants
-they are oxidizing (can oxygen hemoglobin which means it can not longer carry oxygen)
-anthropogenic source: combustion of fossil fuels (petroleum from cars)
toxic effects
-plants: inhibition of photosynthesis and lipid biosynthesis
-humans: irritation of lungs, lowered hemoglobin, depressed immune functions
what is carbon monoxide?
CO, primary air pollutant (way more toxic that CO2)
anthropogenic sources:
-combustion of carbonaceous materials including hydrocarbons
-can remain in the atmosphere up to 1 month before being oxidized to CO2
is the level of carbon monoxide going up or down?
what are the toxic effects of carbon monoxide?
-hypoxia -tightly bind to hemoglobin (with 200x greater affinity than oxygen)
-critical tissue damage (e.g. brain)/death
-immune and cardiovascular impairment
-neonatal effects: reduced birth weight
what is the graph of the symptoms/effects of CO exposure on humans?
doesn’t necessarily health to put person in oxygen chamber, because CO binds so tight to Hb
what are the CO exposure limits in canada?
what are VOCs (primary air pollutant)?
volatile organic carbons
anthropogenic source:
-carbon-containing gases and vapors (including PAHs) such as gasoline fumes and solvent (but excluding carbon dioxide, carbon monoxide, and chlorofluorocarbons)
toxic effects: humans
-carcinogenicity (especially PAHs)
-neurotoxicity
what did the discover about PAHs?
leads to indoor exposure through inhalation and dermal
-remove 50% in washing machine
what are the types of particulate matter (primary air pollutant)?
-coarse particulates (PM10)
-fine particulates (PM2.5)
-ultrafine particulates (PM0.1)
what are coarse particulates?
10 microns
-pollen, sea salt and particles from man-made products (e.g. tires, concrete)
-metal oxides of silicon, aluminum, calcium and iron
-coarse particulates precipitate quicker (dont stay suspended in the air for long periods of time)
-dont penetrate as deep into lungs
what are fine particulates?
2.5 microns
-carbonaceous materials, sulfates, ammonium, and nitrates
-trace metal compounds (Ni, Pb, Zn, Cu and Al)
-small particulates are charged, but also bind to lipophilic compound
what are ultrafine particles?
0.1 microns
-same composition as PM2.5
how small is particulate matter compared to human hair?
what are the sources of PM<10 and PM<2.5 in canada?
what is the global annual PM<2.5 concentration change from 2001 to 2010?
what are the concentrations of PM2.5 in cities around the world?
why is the annual PM2.5 average concentration misleading?
some days have levels that are way above safe levels
what is the pie chart on air quality?
pie chart showing total global exposure to particulate matter air pollution
-very large footprint for indoor because biomass fuels (wood, coal)
what is the graph of the lungs?
-alveoli are very sensitive and delicate
-alveoli is site of gas exchange
-alveoli has only one layer of epithelial cells
what is the graph of uptake by ultrafine particles in mice lung?
red=distribution of particles in lung
what is the mode of toxic action of fine particulates?
inflammation (inflammatory response): triggered by cell injury or pathogens (recruits white blood cells)
can have adverse effects
-sustained activation of immune response leads to chronic inflammation (level of white blood cells will go up and it is more common is big cities)
-more white blood cells=more oxidative stress
what are the toxic effects in humans of particulate matters?
-fine particles retained in lungs
-lung and systemic inflammation
-chronic bronchitis, COPD (air tubes become more stiff due to swelling and results in less air flow to lungs)
-induce acute cardiovascular events (fine and ultra are major source of lung cancer)
