The Car Park I wish to monitor is indoors, does the IoTPortal system have any sensors available for monitoring air quality?

Yes, BRT Systems offers several models of LDSBus air quality sensors, namely, LDSBus CO2 and LDSBus CO2-Pro sensors which measure CO2, temperature, humidity and outdoor ambient light, LDSBus TrueVOC sensors that measure volatile organic gases and LDSBus Air Quality Sensor which measure air quality referenced to an international standard index.