This study compares the first residential PassivHaus in Mexico City to a standard building practice home in terms of indoor environment quality, specifically indoor air quality (IAQ) and occupants’ perception towards it. IAQ was measured during the months of May, June and July. Temperature, relative humidity, carbon dioxide, and particulate matter 2.5 were monitored in the living room, bedroom and kitchen of each of the homes. Simultaneous outdoor measurements were collected from the local pollution monitoring network. Online surveys and an occupancy diary were used to gain data about building-related illness; occupants IAQ and thermal comfort perception; as well as behaviour in both flats. Results suggest that the PassivHaus design helps to protect occupants from the outdoor pollution. Lower concentrations of contamination were found in the PassivHaus than the external environment. This contrasted with the results of the standard building practice home, in which indoor pollution was found to be higher than the outdoors.