Area and Mobile Sources 

In the world of Emissions Inventory Area Sources are those sources that are too numerous to do individual inventories.  The Division of Air Quality gathers data to calculate emissions from these sources as a group for each county.  Dry cleaners and  gasoline stations are common examples of Area Sources but there are many more.  This effort is too labor intensive to calculate the emissions annually.  Area Source inventories fall into the category of Periodic Emissions Inventories and are done every three years.

Mobile Sources are similar in that only periodic  inventories are calculated.  Mobile emissions include On-Road and Off-Road categories as well as many subcategories of each.  On-Road includes all types of engines and vehicle types.  Off-Road includes marine vehicles, lawn equipment, etc.