I went to a BALPA conference on contaminated cabin air about three years ago. Leaving aside whether the toxins should be there in the first place, there was some useful info on filters.
The point about filtering the air is that there is currently no practical 'barrier-type' filter which will work 100% without stopping air flow. There are absorbent filters that can be fitted to the sides of the ducts, but by definition they cannot filter everything.
With current technology the best chance we have is with the much-maligned air recirculation system. As well as improving humidity it does have effective filtration capable of removing SARS virus and other small toxins. Obviously the contaminants will already be in the cabin and some damage will already be done, but the recirculation filters should take it out pretty quickly. Unfortunately the minute recirculation is mentioned, the press is full of hysteria about airlines starving passengers of oxygen to save fuel.
For the future the 787 has bleedless engines, so somebody is worried about the problem (and the litigation). From the past, Dart engines had Rootes Blowers which provided air but could also be contaminated with oil.