Air contaminant filtration system for a cabin

1. An air contaminant filtration system for a cabin comprising:

an external air drawing system for drawing air from an atmosphere surrounding the cabin;

an internal air extraction system for drawing air from an atmosphere within the cabin;

a main filtration system; and

a filtered air delivery system in the form of a prior installed air conditioning system for the cabin with its fan removed,

where, air drawn from the external drawing system and from the internal air extraction system is directed towards the main filtration system for filtration and the filtered air is then directed towards the filtered air delivery system for delivery to the cabin.

2. An air contaminant filtration system according to claim 1 , where the external air drawing system incorporates pressurising means for pressurising the air drawn from the atmosphere prior to delivery to the main filtration system.

3. An air contaminant filtration system according to claim 2 , where the pressurising means is a pressurisation fan.

4. An air contaminant filtration system according to claim 2 , where the pressurising means is a pressurisation filter.

5. An air contaminant filtration system according to claim 1 , where the external air drawing system incorporates at least one external air filter for filtering air drawn from the atmosphere prior to delivery to the main filtration system.

6. An air contaminant filtration system according to claim 1 , where the main filtration system incorporates a plurality of main filters for filtering air received from the external air drawing system or the internal air extraction system.

7. An air contaminant filtration system according to claim 6 , where the plurality of main filters are arranged in parallel.

8. An air contaminant filtration system according to claim 6 , where the plurality of main filters are arranged so as to provide multi-stage filtration of air received from the external air drawing system or the internal air extraction system.

9. An air contaminant filtration system according to claim 6 , where the main filtration system incorporates directing means to direct air drawn from the external air drawing system or the internal air extraction system towards a set of filters selected from the plurality of main filters.

10. An air contaminant filtration system according to claim 5 , where the external air filter comprises at least one of: a high efficiency particle air filter; active carbon filter.

11. An air contaminant filtration system according to claim 1 , where the main filtration system includes circulation fans to draw air from the external air drawing system and the internal air extraction system.

12. An air contaminant filtration system according to claim 1 , where at least the external air drawing system is contained within a housing external to the cabin.

13. An air contaminant filtration system according to claim 12 , where the housing is attached to roof racks and the roof racks are attached to the cabin.

14. An air contaminant filtration system according to claim 12 , where the housing further incorporates an external vehicle identification system.

15. An air contaminant filtration system according to claim 12 , where the housing further incorporates an external visual and/or audio safety system.

16. A method of filtering air contaminants for a cabin comprising the steps of:

drawing air from an atmosphere surrounding the cabin;

drawing air from an atmosphere within the cabin;

filtering the drawn air from both atmospheres; and

delivering the filtered air to the cabin by way of a prior installed air conditioning system for the cabin with its fan removed.

17. A method of filtering air contaminants for a cabin according to claim 16 , where the method further includes the step of pressurising the air drawn from the atmosphere surrounding the cabin.

18. A method of filtering air contaminants for a cabin according to claim 16 , where the method further includes the step of pre-filtering the air drawn from the atmosphere surrounding the cabin before the step of filtering the drawn air from both atmospheres.

19. A method of filtering air contaminants for a cabin according to claim 16 , where the step of filtering the drawn air from both atmospheres comprises the substeps of filtering the drawn air from both atmospheres using a primary filter and then filtering the drawn air from both atmospheres using at least one secondary filter.

20. A method of filtering air contaminants for a cabin according to claim 16 , where the method further includes the step of filtering the drawn air from both atmospheres includes the substep of directing air drawn from one or both atmospheres toward a particular filter.

21. A method of retrofitting a vehicle cabin to include an air filtration system for use with a filtered air delivery system in the form of an air conditioning unit already installed in the vehicle cabin, the method comprising the steps of:

removing all fans from the air conditioning unit;

installing the air filtration system to an external side of a roof of the vehicle cabin; and

connecting the air filtration system to the air conditioning unit so that air filtered by the air filtration system can be delivered to the cabin by way of the air conditioning unit.