A major source is a facility or activity that emits, or has the potential to emit, 10 tons per year (tpy) or more of any air pollutant, or 25 tpy or more of any combination of air pollutants.
Transportation and fossil fuel industries typically come to mind as major sources of pollution. (sciencedaily.com)
A second major source for skepticism: Evidence of the fish, shrimp and worms don't come from finding DNA snippets from those actual critters. (sciencenewsforstudents.org)
The data suggest wind and solar are quickly becoming major sources of electricity, brushing aside perceptions that they're too expensive to rival traditional fuels. (bloomberg.com)