AIR POLLUTION

BEFORE WE CAN TALK ABOUT AIR POLLUTION, WE NEED TO TALK ABOUT THE NATURE OF GASES (AIR).

IN A GAS, THE MOLECULES ARE IN CONSTANT MOTION.

THE KINETIC THEORY OF GASES MAKES THE FOLLOWING STATEMENTS ABOUT A GAS:

1. THE MOLECULES ARE SMALL COMPARED TO THE DISTANCES BETWEEN THEM.

2. THERE ARE FREQUENT COLLISIONS BETWEEN THE MOLECULES.

3. THE TEMPERATURE IS A MEASURE OF THE MEAN KINETIC ENERGY OF THE GAS.

SINCE THE MOLECULES ARE CONSTANTLY IN MOTION, A CLOUD OF GAS IS CONTINUALY EXPANDING IN ALL DIRECTIONS.

WE REFER TO THIS AS DIFFUSION.

IN OTHER WORDS, A CLOUD OF POLLUTANT GAS IS NOT JUST SITTING STILL. IT IS DIFFUSING IN ALL DIRECTIONS.

IN ADDITION, YOU HAVE THE EFFECT OF THE WIND TO CONSIDER.

TAKE A LOOK AT THE SMOKE COMING OUT OF A SMOKE STACK.

GENERALLY, THE WIND IS MOVING THE SMOKE IN A GIVEN DIRECTION, AND THE PLUME IS EXPANDING AT THE SAME TIME.

THIS WOULD BE TRUE NO MATTER WHAT THE SOURCE OF THE GAS - THE TAIL PIPE OF A CAR, OR THE CHIMMNEY OF A COAL-FIRED POWER PLANT.

THIS MAKES AIR POLLUTANTS DIFFICULT TO DEAL WITH.

ONCE THEY ARE EMITTED, THEY CANNOT BE CONTAINED.

IN THE CASE OF SOLID OR LIQUID CONTAMINANTS, YOU COULD DAM UP A CREEK, PUT A BOOM AROUND AN OIL SPILL, OR DIG UP CONTAMINATED LAND.

YOU CANNOT CONTAIN AIR POLLUTION.

THE BEST OPTION IS TO PREVENT IT.

THIS MAKES DEALING WITH AIR POLLUTIION RATHER COMPLICATED.

CONCENTRATIONS AWAY FROM A SOURCE ARE IMPACTED BY WIND SPEED, DIRECTION, TEMPERATURE, DISTANCE, AND THE HEIGHTH OF THE STACK JUST TO NAME A FEW.

FORTUNATELY, A NUMBER OF COMPUTER MODELING PROGRAMS EXIST THAT TAKE INTO ACCOUNT A NUMBER OF THESE FACTORS.

THESE PROGRAMS MAKE IT POSSIBLE TO CALCULATE THE CONCENTRATION OF POLLUTANTS AT DIFFERENT DISTANCES FROM A SOURCE UNDER DIFFERENT WEATHER CONDITIONS.

AIR POLLUTION CAN OCCUR INDOORS OR OUTDOORS.

FIRST - OUTDOORS.

WHEN WE THINK OF AIR POLLUTION, WE GENERALLY THINK OF BELCHING SMOKE STACKS KICKING OUT ALL SORTS OF NOXIOUS VAPORS.

THAT IS OFTEN NOT THE CASE.

IN THE TRIAD AREA OF NORTH CAROLINA, THE USUAL AIR POLLUTANTS ARE PARTICULATES AND OZONE - BOTH MOSTLY FROM VEHICULAR EMISSIONS.

PARTICULATES

PARTICULATES INCLUDE SOLID OR LIQUID PARTICLES FROM VARIOUS SOURCES.

EPA DIVIDES PARTICULATES INTO TWO CATEGRORIES.

1. INHALABLE COARSE PARTICULATES - THESE ARE PARTICLES BETWEEN 2.5 AND 10 MICRONS IN DIAMETER. THESE ARE FROM ROADWAYS AND DUSTY INDUSTRIES.

2. FINE PARTICULATES - 2.5 MICRONS IN DIAMETER OR SMALLER. THESE ARE FORMED FROM FIRES OR THEY CAN BE FORMED FROM GASES EMITTED BY INDUSTRIES OR AUTOMOBILES.

THE EPA DOES NOT REGULATE PARTICULATES ABOVE 10 MICRONS IN SIZE, AS THEY ARE NOT RESPIRABLE.

THE SMALLER THE PARTICLE, THE MORE RESPIRABLE - THE DEEPER INTO THE LUNG IT WILL BE CARRIED.

THE PARTICLES BELOW 2.5 MICRONS IN SIZE ARE ALSO RESPONSIBLE FOR HAZE AND REDUCED VISIBILITY.

THIS IS A PROBLEM IN SOME NATIONAL PARKS.

HEALT EFFECTS (EPA)

* increased respiratory symptoms, such as irritation of the airways, coughing, or difficulty breathing, for example;

* decreased lung function; * aggravated asthma; * development of chronic bronchitis; * irregular heartbeat; * nonfatal heart attacks; and * premature death in people with heart or lung

disease.

THE EPA PARTICULATE STANDARDS ARE:

PM10 150 ug/m3 for 24 hours

PM2.5 15 ug/m3 annual (arithmetic mean)

35 ug/m3 for 24 hours

THE OTHER POLLUTANT THAT IS IMPORTANT LOCALLY IS OZONE.

OZONE CAN OCCUR AT GROUND LEVEL OR IN THE STRATOSPHERE.

OZONE IN THE STRATOSPHERE IS GOOD, AS IT ABSORBS UV RADIATION THAT WOULD BE DANGEROUS TO LIVING ORGANISMS.

OZONE AT GROUND LEVEL IS DANGEROUS, AS IT CAN DAMANGE LUNG FUNCTION.

O3

OZONE - GOOD UP HIGH; BAD NEAR BY.

UV RADIATION DRIVES OZONE FORMATION AS WELL AS ITS DESTRUCTION:

OZONE FORMATION OZONE DESTRUCTION

AT GROUND LEVEL, OZONE IS FORMED IN A SERIES OF STEPS INVOLVING OXIDES OF NITROGEN (NOX), VOLATILE ORGANIC COMPOUNDS (VOC’S), AND SUNLIGHT.

OXIDES OF NITROGEN ARE EMITTED BY ELECTRICAL GENERATING PLANTS AND BY VEHICULAR EMISSIONS.

VOLATILE ORGANIC COMPOUNDS ARE EMITTED BY AUTOMOBILES AND TRUCKS AS WELL AS BY NATURAL SOURCES (TREES).

SUNLIGHT PROVIDES THE ENERGY.

NEW YORK CITY BEFORE AND DURING PHOTOCHEMICAL SMOG.

HEALTH EFFECTS OF OZONE

* Irritation of the respiratory system, causing coughing, throat irritation, and/or an uncomfortable sensation in the chest.

* Reduced lung function, making it more difficult to breathe deeply and vigorously. * Aggravation of asthma. * Increased susceptibility to respiratory infections. * Inflammation and damage the lining of the lungs.

CATALYTIC CONVERTERS IN AUTOMOBILES CAN HELP BY ELIMINATING SOME OF THE VOC’S AND OXIDES OF NITROGEN.

platinum catalystC5H12 (pentane) + 8 O2 -------------------------> 5CO2 + 6 H2O

rhodium catalyst2 CO + 2 NO ------------------------> 2 CO2 + N2

ACID RAIN

ACID RAIN COMES FROM THE BURNING OF FOSSIL FUELS AND THE EXTRACTION OF METALS FROM ORES.

ACID RAIN IS CAUSED BY THE GENERATION OF SO2 AND NOX.

ABOUT 2/3 OF ALL SO2 AND 1/4 OF ALL NOX COMES FROM COAL FIRED POWER PLANTS.

ABOUT 2/3 OF NOX COMES FROM VEHICULAR SOURCES.

SO2 REACTS WITH OXYGEN AND WATER IN THE ATMOSPHERE TO FORM SULFURIC ACID.

NOX REACTS WITH OXYGEN AND WATER IN THE ATMOSPHERE TO FORM NITRIC ACID.

THESE ACIDS CAN BE CARRIED TO EARTH BY RAIN OR OTHER FOMRS OF PRECIPITATION AS ACID RAIN (WET DEPOSITION).

THESE MATERIALS CAN ALSO ATTACH TO PARTICULATES IN THE ATMOSPHERE AND BE CARRIED TO EARTH (DRY DEPOSITION).

ACID RAIN HARMS LAKES AND STREAMS AND DAMAGES TREES AT HIGHER ELEVATIONS.

ACID RAIN CAN ALSO DAMAGE BUILDINGS AND OTHER OUTDOOR FIXTURES.

THE POLLUTANTS THAT CAUSE ACID RAIN CAN ALSO IRRITATE LUNGS.

pH Effect on Aquatic Species

3.0-3.5 Unlikely that fish can survive for more than a few hours in this range although some plant and invertebrates can be found at pH levels this low.

3.5-4.0 Known to be lethal to all salmonids.

4.0-4.5 All fish, most frogs and insects are not present.

4.5-5.0 Mayfly and many other insect species are not found. Most fish eggs will not hatch.

5.0-5.5 Bottom-dwelling decomposing bacteria begin to die off. Leaf litter and dead plant and animal materials begin to accumulate. Plankton begin to disappear.

6.0-6.5 Freshwater shrimp are not present.

6.5-8.5 Optimal for most organisms.