To monitor an individual’s exposure to pollution over the course of a typical day, the monitoring device must be highly portable as it will travel with a person indoors and out, almost certainly via several modes of transport. The Praxis/Handheld may be ‘on the move’ for several hours before being returned to base and because of this, it is equipped to store large amounts of data until it reconnects with a wi-fi network. Alternatively, the user can upload to the cloud in real-time via a mobile phone hotspot.