lect 3 pollutants units and regs Air quality

Chlorofluorocarbons CFCs impacts (2)

very stable/inert in troposphere, releases Cl in stratosphere which destroys ozone

sources of CFCs

leaking refrigerants, propellants, and solvents

Hydrochlorofluorocarbons (HCFCs) tell me about em compared to CFCs

similar effects to CFCs but shorter residence time i the atmosphere (less damaging)

how are CFCs and HCFCs regulated (1st ban, 2 other ways)

1st ban by US EPA in 1978 under Toxic Substances control act

alternatives to CFCs and HCFCs

HFCs, HCs, NH3, CO2

CO2 impact

GHG

sources of CO2

fuel (hydrocarbon) combustion

how is CO2 regulated (3)

fuel economy standards, mandatory reporting system, active research on new control techniques

Hg impact

persistent and toxic compound, deposition → watershed → methylmercury → fish, fetuses exposed before birth are more likely to have neurobehavioral problems

source of Hg pollution

power plant emissions

how is Hg regulated

clean air mercury rule, cap and trade approach to limit emissions, becoming a global issue

sources of VOCs

evaporation of fuels and solvents, incomplete combustion, natural sourcesho

how are VOCs regulated

some air toxics and regulated as O3 precursor

HAPs

air pollutants that can cause serious health and environmental problems

how are HAPs regulated

EPA maintains a list and regulates HAPs

mixing ratio or mole fraction

Cx = Vpollutan/Vtotal or Cx = molespollutant/moles total

_________ remains constant when _________ changes

mixing ratio, air density

mixing ratio is a _______ measure of __________ ___________

robust, atmospheric composition

mass concentration formula for aerosols and occasionally for gases

rho x = mass of X (pollutant) / unit volume of air

mass concentration fomula for gases

rho x = Mx P/ RT * Cx