How about a 'filter' that can 'wash' the air with clean water. To me it appears to me the best possible solution to clean air in a confined space. To put it simply, air can be bubbled through the clean water, to scrub it of both particulate and chemical contaminants. No doubt the apparatus will lend itself to several technical challenges like noise and the need for periodic changes of the water.
The main problem of air washers is that it is not enough to change the water.
Fungus and spiders love the wet environment. Algae start growing if there is sunlight using just the dust particles on air as food. Also very bad bacteria like salmonella and others could grow if the water gets warm.
I believe such air purifiers already exist.