Engineered nanoparticle detection in the ambient air?

Currently, the detection of engineered nanoparticles is a very delicate exercise. In air, the important and variable background noise (~ 104 part.cm-3 in the range of 5 nm to 350 nm) most of the time masks an increase in concentration due, for example, to a leak on a process. The high temporal variability of this background noise is a sensitive issue for physical instrumentation.