These sources will get you started exploring environmental problems and policy areas. Take a look at the Articles tab on left for more sources.
North American Industry Classification System (NAICS) Codes are used to track and compare data
Code System Uses 3 to 7 digits
Some data is only reported at the 3 digit level. Important to note that limitation in your paper. (Usually just a sentence or two clarifying data only available at the broader level, which includes more than just your product).
|Large Manufactured Product||NAICS code|
|Aluminum, Primary||331312; 331313 (2012+)|