Residents of apartments in a partially-enclosed courtyard raised concerns about plans for an adjacent condominium development that would totally enclose the courtyard. Their concerns originated from possible effects from emissions from underground parking garages. Based on a literature review, Airzone derived simple techniques to estimate worst-case impacts on air quality within the courtyard. Our conclusions remained uncontested by expert reviewers representing the condominium developers resulting in concessions from the condominium developers to substantially alter their building design so as to avoid enclosing the courtyard.