It depends how you measure it, and what counts as ‘polluting’. Does broad-scale habitat destruction count? Because there’s a lot more of that in industrial agriculture. Also yields are prioritised over quality, so you’re literally not comparing apples with apples if you’re getting local heirloom varieties from nearby orchards, compared with apples grown in the PNW for the broader market and kept chilled until ready for sale. These are generalisations of course and there are staple crops that are much more efficient when produced with broadacre cropping.