Measurements of Charged Aerosols Near $\pm$500-kV DC Transmission Lines and in Other Environments

Current methods that assess the charge on aerosols downwind of transmission lines are not capable of determining the net charge per aerosol. A new method was used to measure the charge on aerosols upwind and downwind of two dc transmission lines in 38 measurement sessions and on aerosols in urban, suburban, and rural environments near Chicago, IL and Winnipeg, MB, Canada, in another 22 measurement sessions. The prevalence of charged aerosols around the dc lines and other environments was similar. Both upwind and downwind of the dc lines and in other environments, the distribution of the aerosol charge is bimodal, and the modal charge is one charge per aerosol. Downwind of the dc lines, the percent of aerosols with positive charge is reduced and the percent of aerosols with negative charge is increased. Despite this shift, the modal charge did not change and almost all aerosols carried fewer than 10 charges.