***Air Quality Management: The North Carolina Compliance Modeling  Project*
Ground level ozone, or "smog," threatens animal and plant life.   Occurring naturally in lowconcentration, ozone is harmless.   However, air pollution can increase ozone concentrations to the point where it can severely irritate lungs, nasal passages, and eyes;  reduce disease resistance;reduce crop yields; and injure trees.  Crop  losses alone due to ozone are estimated to be $3 to $5billion  annually in this country.  The problem is so pervasive that  newspapers and televisionstations in many areas daily report  pollution level indicators in the summer.  Periodically health officials issue warnings for children and the elderly to remain  indoors if ozone concentrations aredangerously high. 
Ozone is produced through complex chemical reactions primarily  involving volatile organic compounds(VOCs) and oxides of nitrogen  (NOx).  These ozone precursors are produced by automobiles,  factories,and even by natural processes such as lightning and  vegetative growth.  To ensure that ozone levelsare within  acceptable ranges for a given region, the VOCs and/or NOx emissions  may need to becontrolled.  These controls are usually costly, and  ill-suited controls may not even make muchdifference in the ozone  levels that a region experiences.  Since 1980, over $800 million has  beenspent in Atlanta on ozone reduction measures with only limited  success.  Ozone levels have not beenreduced, but they have not  increased either, despite significant population growth. 
The Charlotte, NC, area is another region that has experienced  unhealthy ozone levels.  Previousozone modeling efforts have  indicated that VOC reductions lower ozone levels more than NOx reductions do.  However, these results were obtained for regions  that have more significant ozoneproblems than Charlotte has,  regions that are generally more urbanized.  Given that the character  ofthe ozone problem in Charlotte may not match what is found in  more urban areas, and considering theenormity of potential control  costs, the North Carolina Division of Environmental Management  (NCDEM)has employed HPCC technologies to determine an effective  control strategy for the Charlotte region. The NCDEM used the Urban  Airshed Model (UAM) to model the effects of numerous emissions  controls. The figure shows that reducing VOCs in the Charlotte  region has a minimal effect on modeled ozone,whereas NOx  reductions significantly reduce the modeled ozone concentrations.   This indicates thatthe ozone problem in the Charlotte vicinity  differs from that in the more urban areas and should beaddressed  accordingly. 
The importance of HPCC in modeling control strategies for ozone is  not so much in determining whetherglobal controls should be placed  on VOCs or NOx, but rather in quantifying the effects thatparticular  plants, factories, or highways have on the modeled ozone field.  To  extract this amountof detail, the UAM must be run with numerous  control strategies for a variety of meteorologicalconditions.  This  process requires hundreds of UAM executions, each execution  requiring significantcomputer resources.  Outside of an HPCC  environment, these model runs simply could not be made in atimely  manner.  Important decisions affecting the economics and health of  an area would be made witha skeletal amount of modeling  information, possibly resulting in an ill-conceived control strategy.  Such a plan might place an inordinate economic burden on some  industrial segments, while notsignificantly improving the air  quality of the region.  More serious polluters, on the other hand, might not be targeted for meaningful controls. 
The principal collaborators in this project include EPA, the North  Carolina Supercomputer Center, theNorth Carolina Division of  Environmental Management, the University of North Carolina at  ChapelHill, Duke University, Carolina Power and Light, and Systems  Applications International.  Thiscollaboration ensured that the  economic concerns of potential control targets would be addressed, resulting in a control package that is not only environmentally  friendly but also economicallyfeasible. 
  http://www.iceis.mcnc.org/publications/bluebook/**