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

Air Quality

Atmospheric Composition Nitrogen78.0% Oxygen20.1% Argon0.9% Carbon Dioxide0.03% Neon0.002% Helium0.0005% 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 added to air at sufficiently high concentrations, will cause adverse effects.

Meteorology and Air Movement Troposphere: 5 km thick at poles, 18 km at equator. Temperature decreases with altitude. More than 80% of the mass of the atmosphere Stratosphere: little mixing. Temperature profile inverted. High ozone concentration. Only 0.1% mass of air in layers above stratosphere

Pollutants are generally only a problem in the troposphere. The exception is ozone depletion problem in the stratosphere. Pollutants may be either naturally produced or manmade and are moved through the atmosphere by air currents we call wind. Wind may be caused by many different phenomena ranging from global wind patterns caused by the differential warming and cooling of the earth as it rotates under the sun, to local winds caused by differential temperatures between land and water masses. Wind not only moves pollutants horizontally, but also causes the pollutants to disperse, reducing the pollutant concentration as it moves away from the source. The amount of dispersion is directly related to the stability of the atmosphere, or how much vertical movement is taking place

As an imaginary parcel of air rises through the atmosphere it experiences lower and lower pressure so it expands. The expansion causes the temperature to drop (thermodynamics) Ideally a parcel of air will cool at about 1 o C/100 m or 5.4 o f/1000 ft This is called the dry adiabatic lapse rate (adiabatic means no heat transfer between the air parcel and the surrounding air). It is independent of the atmospheric conditions and always holds for dry air. When there is moisture in the air the rate is different (called the wet adiabatic lapse rate) because of the evaporation and condensation of moisture in the atmosphere

The actual temperature versus elevation measurement is called the prevailing lapse rate (solid lines below) Superadiabatic lapse rate (or strong lapse rate) is when the actual atmospheric temperature drops more than 1 o C/100 m Subadiabatic lapse rate (weak lapse rate) is when the actual temperature drops less than 1 o C/100 m A special case of the weak lapse rate is called an inversion. This is where warm air is above cool air

If superadiabatic conditions apply, this atmosphere is called unstable. If Subadiabatic conditions exist, especially inversions conditions the atmosphere is called stable

Example A stack 100 m tall emits a plume at 20 o C. The prevailing lapse rates are shown in the figure below. How high will the plume rise (if we assume dry adiabatic conditions)? The prevailing lapse rate is subadiabatic to 200 m and there is an inversion above 200 m. The smoke at 20 o C finds itself surrounded by colder air (18.6 o C) so it will rise. As it rises it cool, so that at 200 m it is 19 o C. At about 220 m, the surrounding air is at the same temperature (about 18.7oC) and so the smoke will stop rising.

Inversions Subsidence 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 earth cools, causing the air close to the ground to be cooler than the air above it. Often accompanied by fog

Major Air pollutants

Particulates Dust: solid particle that: a)Entrained by process gases directly from material handling or processing b)Direct offspring of parent material undergoing a mechanical operation c)Entrained materials used in a mechanical operation

Fume: solid particle, often a metal oxide, formed by the condensation of vapors by sublimation, distillation, calcination, or chemical reaction processes Mist: entrained solid particles formed by the condensation of a vapor Smoke: entrained solid particles formaedas the result of incomplete combustion of carbonaceous materials. Spray: liquid particle formed by the atomization of a parent liquid

Measurement of Particles High-Volume Sampler (Hi-vol) Total Suspended particulates (TSP) PM 10 Respirable particulates

Gaseous Pollutants

Measurement of Gases