Box Canyons and Carbon Monoxide Poisoning

I have a current project for a PUD for a student apartment housing complex here in town. A resident and neighboring property owner to the proposed PUD has come forward with a report he created stating that the proposed project will create a “modified box canyon” that will place everyone in the area in danger of carbon monoxide poisoning. I have never heard of such a thing and my research has not turned up anything. I was wondering if this is something that anyone has come across. Thanks.