There’s no question that our buses emit diesel fumes and it’s momentarily bothersome if you’re right there when they pass, but smog? I wouldn’t go that far. Numerous routes have recently been eliminated from El Centro, and completion of a light rail line currently under construction will be a huge improvement.
We’re at 8400 feet, so I never recommend Cuenca to people with respiratory issues. New arrivals sometimes have headaches or a little shortness of breath initially, but most report no symptoms from the altitude.