Lecture 9: Air Pollution Flashcards
Air pollution episode
several day period of high pollution associated with adverse health outcomes
london pennyslvania etc
highly industrialized sections
• high coal use
• winter time occurrence
• prolonged inversion (typically 3-5 days)
• unexpected high number of deaths for individual with
preexisting bronchitis, emphysema or heart trouble.
Examples of well known air pollution episodes (and sour
Inversion
increase in air temperature with height. decreased horizontal wind movement, greatly reduced vertical mixing, nocturnal, frontal, subsidence
types of pollutants
conventional, global, criteria (NOx, SOx, Lead, Pb, PM, O3, CO)
• Conventional pollutants (criteria pollutants)
– Sulfur dioxide, nitrogen dioxide, lead, ozone, carbon monoxide,
particulate matter
• Toxic pollutants (hazardous air pollutants)
– Local – benzene, diesel exhaust
– Regional – mercury, PCBs, PBDEs
– Global – Chlorofluorocarbons (CFCs)
• Greenhouse pollutants (only short-lived are toxic)
– Long lived - carbon dioxide (CO2), nitrous oxide and halocarbons
(N2O, F11, F12, etc)
– Medium lived - methane (CH4)
– Short lived - carbon monoxide (CO), non-methane volatile organic
compounds (NMVOCs)
• Indoor pollutants
Summary of Common Air Pollution problems
127 million people live in an exceedence of one sort or another (mostly 03 since they changed the standard to be 8 hour, second is PM)
coal fired power plants are largest SO2 emitters, SO2 has decreased over time
O3 concentration has not decreased
Pm2.5 levels have decreased
Types of Emission Sources, what is the national database for these sources
Point Source, Area Souce, Mobile or vehicle, fugative
NEI
what is the source, transport, receptor pathway?
emission sources - fate and transport (primary and secondary pollutants), receptors and impacts
phases
vapors - gas phase of a pollutant that is liquid or solid at room temperature
volatility - very volatile (formaldehyde), volatile (benzene), semi-volatile (dioxins)
Pm definitions
particle (solid, may be many units, > 0.001 mm) , aerosol, - microscopic solid or liquid (monodisperse or polydisperse)
droplet - aerosol which settles under normal conditions, but stays afloat due to turbulence
fog - visible liquid aerosols
mist - larger visible liquid aerosols
Pm formation
formation processes generate different size aerosols, size changes in atmosphere due to chemical processes, size affects removal processes by settling, deposition, washout and rainout
Pm distributions are different when you look at number, surface area, and volume
Origin of PM
primary pollutant: sources may emit PM directly into the environment, point, mobile, fugative, non point, natural
secondary pollutant: formed by chemical rxn in the environment sulfur dioxide (SO2) + ammonia = PM nitrogen dioxide (NO2) + ammonia = PM volatile organic compounds (VOCs) = PM
Deposition
A mechanism that removes airborne materials from the
atmosphere and deposits them on a surface
Wet deposition (removal from air collumn due to precip or fog scavenging), dry deposition (settling or fallout due to gravity, or attraction due to physical or chemical properties),
terms for air pollutants which SB does NOT like
DUST: Solid particles predominantly larger than colloidal andcapable of temporary suspension. Dusts do not flocculate (exceptunder electrostatic forces), do not diffuse, but settle underinfluence of gravity.
FUME: Solid particles generated by condensation from the gaseous state, generally after volatilization from melted substances. Fumes flocculate, often react, and may coalesce.
SMOKE: Finely divided aerosols resulting from incomplete combustion. Composed largely of carbon and other combustion material.
SOOT: Agglomerations of carbon particles impregnated with “tar” formed in complete combustion.
SMOG: Term derived from smoke and fog, originally applied to extensive contamination by aerosols.
Layers of the Atm
0 - 50 0- 500 > 500 0 - 10km 10 - 30km
