A little diet advice: A little diet advice:   A) The Japanese eat very little fat and suffer fewer heart attacks than the A) The Japanese eat very little fat and suffer fewer heart attacks than the British or Americans. British or Americans.   (B) On the other hand, the French eat a lot of fat and also suffer fewer (B) On the other hand, the French eat a lot of fat and also suffer fewer heart attacks than the British or Americans. heart attacks than the British or Americans.   (C) The Japanese drink very little red wine and suffer fewer heart attacks (C) The Japanese drink very little red wine and suffer fewer heart attacks than the British or Americans. than the British or Americans.   (D) The Italians drink excessive amounts of red wine and also suffer fewer heart attacks (D) The Italians drink excessive amounts of red wine and also suffer fewer heart attacks than the British or Americans than the British or Americans   (E) Conclusion: Eat & drink what you like. It's speaking English that kills (E) Conclusion: Eat & drink what you like. It's speaking English that kills you.you.

Air QualityAir Quality

Atmospheric CompositionAtmospheric Composition

NitrogenNitrogen 78.0%78.0%OxygenOxygen 20.1%20.1%ArgonArgon 0.9%0.9%Carbon DioxideCarbon Dioxide 0.03%0.03%NeonNeon 0.002%0.002%HeliumHelium 0.0005%0.0005%

This is pure air. It does not exist. All air contains what we call pollutants.This is pure air. It does not exist. All air contains what we call pollutants.

We will define a pollutant as any material (gas, solid, or liquid) that, when We will define a pollutant as any material (gas, solid, or liquid) that, when added to air at sufficiently high concentrations, will cause adverse effects.added to air at sufficiently high concentrations, will cause adverse effects.

Meteorology and Air MovementMeteorology and Air Movement

Troposphere: 5 km thick Troposphere: 5 km thick at poles, 18 km at at poles, 18 km at equator. Temperature equator. Temperature decreases with altitude. decreases with altitude. More than 80% of the More than 80% of the mass of the atmospheremass of the atmosphere

Stratosphere: little Stratosphere: little mixing. Temperature mixing. Temperature profile inverted. High profile inverted. High ozone concentration.ozone concentration.

Only 0.1% mass of air in Only 0.1% mass of air in layers above stratospherelayers above stratosphere

Pollutants are generally only a problem in the troposphere. The Pollutants are generally only a problem in the troposphere. The exception is ozone depletion problem in the stratosphere.exception is ozone depletion problem in the stratosphere.

Pollutants may be either naturally produced or manmade and are Pollutants may be either naturally produced or manmade and are moved through the atmosphere by air currents we call wind.moved through the atmosphere by air currents we call wind.

Wind may be caused by many different phenomena ranging Wind may be caused by many different phenomena ranging from global wind patterns caused by the differential warming from global wind patterns caused by the differential warming and cooling of the earth as it rotates under the sun, to local and cooling of the earth as it rotates under the sun, to local winds caused by differential temperatures between land and winds caused by differential temperatures between land and water masses.water masses.

Wind not only moves pollutants horizontally, but also causes Wind not only moves pollutants horizontally, but also causes the pollutants to disperse, reducing the pollutant the pollutants to disperse, reducing the pollutant concentration as it moves away from the source.concentration as it moves away from the source.

The amount of dispersion is directly related to the stability of The amount of dispersion is directly related to the stability of the atmosphere, or how much vertical movement is taking placethe atmosphere, or how much vertical movement is taking place

As an imaginary parcel of air rises through the atmosphere it As an imaginary parcel of air rises through the atmosphere it experiences lower and lower pressure so it expands.experiences lower and lower pressure so it expands.

The expansion causes the temperature to drop (thermodynamics)The expansion causes the temperature to drop (thermodynamics)

Ideally a parcel of air will cool at about 1Ideally a parcel of air will cool at about 1ooC/100 m or 5.4C/100 m or 5.4oof/1000 ftf/1000 ft

This is called the This is called the dry adiabatic lapse ratedry adiabatic lapse rate (adiabatic means no (adiabatic means no heat transfer between the air parcel and the surrounding air). It heat transfer between the air parcel and the surrounding air). It is independent of the atmospheric conditions and is independent of the atmospheric conditions and alwaysalways holds holds for dry air.for dry air.

When there is moisture in the air the rate is different (called the When there is moisture in the air the rate is different (called the wet adiabatic lapse rate) wet adiabatic lapse rate) because of the evaporation and because of the evaporation and condensation of moisture in the atmospherecondensation of moisture in the atmosphere

The actual temperature versus elevation measurement is called the The actual temperature versus elevation measurement is called the prevailing lapse rateprevailing lapse rate (solid lines below) (solid lines below)

Superadiabatic lapse rate (or strong lapse rate) is when the actual atmospheric Superadiabatic lapse rate (or strong lapse rate) is when the actual atmospheric temperature drops more than 1temperature drops more than 1ooC/100 mC/100 m

Subadiabatic lapse rate (weak lapse rate) is when the actual temperature Subadiabatic lapse rate (weak lapse rate) is when the actual temperature drops less than 1drops less than 1ooC/100 mC/100 m

A special case of the weak lapse rate is called an inversion. This is where A special case of the weak lapse rate is called an inversion. This is where warm air is above cool airwarm air is above cool air

If superadiabatic conditions apply, this atmosphere is called unstable.If superadiabatic conditions apply, this atmosphere is called unstable.

If Subadiabatic conditions exist, especially inversions conditions If Subadiabatic conditions exist, especially inversions conditions the atmosphere is called stablethe atmosphere is called stable

ExampleExample

A stack 100 m tall emits a plume at 20A stack 100 m tall emits a plume at 20ooC. The prevailing lapse rates are C. The prevailing lapse rates are shown in the figure below. How high will the plume rise (if we assume dry shown in the figure below. How high will the plume rise (if we assume dry adiabatic conditions)?adiabatic conditions)?

The prevailing lapse rate is The prevailing lapse rate is subadiabatic to 200 m and subadiabatic to 200 m and there is an inversion above 200 there is an inversion above 200 m. The smoke at 20m. The smoke at 20ooC finds C finds itself surrounded by colder air itself surrounded by colder air (18.6(18.6ooC) so it will rise. As it C) so it will rise. As it rises it cool, so that at 200 m it rises it cool, so that at 200 m it is 19is 19ooC. At about 220 m, the C. At about 220 m, the surrounding air is at the same surrounding air is at the same temperature (about 18.7oC) temperature (about 18.7oC) and so the smoke will stop and so the smoke will stop rising.rising.

InversionsInversions

Subsidence inversion occurs when a large warm air mass moves over a cooler air massSubsidence inversion occurs when a large warm air mass moves over a cooler air mass

A radiation inversion occurs when air close to the ground loses heat at night as the A radiation inversion occurs when air close to the ground loses heat at night as the earth cools, causing the air close to the ground to be cooler than the air above it.earth cools, causing the air close to the ground to be cooler than the air above it.

Often Often accompanied by accompanied by fogfog

Major Air pollutantsMajor Air pollutants

ParticulatesParticulates

Dust: solid particle that:Dust: solid particle that:

a)a) Entrained by process gases Entrained by process gases directly from material handling directly from material handling or processingor processing

b)b) Direct offspring of parent Direct offspring of parent material undergoing a material undergoing a mechanical operationmechanical operation

c)c) Entrained materials used in a Entrained materials used in a mechanical operationmechanical operation

Fume: solid particle, often a metal oxide, formed by the condensation of Fume: solid particle, often a metal oxide, formed by the condensation of vapors by sublimation, distillation, calcination, or chemical reaction processesvapors by sublimation, distillation, calcination, or chemical reaction processes

Mist: entrained solid particles formed by the condensation of a vaporMist: entrained solid particles formed by the condensation of a vapor

Smoke: entrained solid particles formaedas the result of incomplete Smoke: entrained solid particles formaedas the result of incomplete combustion of carbonaceous materials.combustion of carbonaceous materials.

Spray: liquid particle formed by the atomization of a parent liquidSpray: liquid particle formed by the atomization of a parent liquid

Measurement of ParticlesMeasurement of ParticlesHigh-Volume Sampler (Hi-vol)High-Volume Sampler (Hi-vol)

Total Suspended particulates (TSP)Total Suspended particulates (TSP)

PMPM1010

Respirable particulatesRespirable particulates

Gaseous PollutantsGaseous Pollutants

Measurement of GasesMeasurement of Gases