Measuring The Bipolar Charge Distributions of Fine Particle Aerosol Clouds of Commercial PMDI Suspensions Using a Bipolar Next Generation Impactor (bp-NGI).

The bp-NGI was used to quantify the bipolar Q/m ratios of aerosol particles collected from the ISMs of commercial MDI products. The positive charge recorded for each of the three MDIs may have been enhanced by the presence of charged ice crystals formed from the propellant during the aerosolisation process.