The Chief Science Advisor for the Project on Emerging Nanotechnologies at the Woodrow Wilson International Center for Scholars published an article last week arguing the physics of Brownian motion predict that highly dispersed nanoscale particles in aerosols are unlikely to agglomerate, thus fueling ongoing nano-EHS inhalation concerns.  On the other hand, some scientists say it is extremely difficult to generate aerosols consisting of non-agglomerated nanoparticles in the first place.  A considerable amount of time and money has been spent developing equipment capable of generating these types of aerosols so they can then be used in EHS testing.  It’s not an easy task.  Another question is whether simply using nanoscale materials in a workplace setting necessarily means that clouds of aerosolized discrete nano particles are actually being generated.  A further issue is what happens when two nanoscale particles actually collide — whether before, during, or after the aerosolization process.  How likely is it that they will separate back into nanoscale particles.  Comments?