The timescale dependent relationships between the atmospheric electrical conductivity and concentrations of aerosol particles, carbon monoxide, sulfur dioxide, and nitrogen dioxide in downtown Toronto were examined by spectral analyses based on a year of hourly averaged observations at a single site during 1973--1974. The highlights of the relationships were found as follows: (1) The variance spectra (or power spectra) of both electrical conductivity and pollutant concentrations obeyed the -5/3 power law of spectral decay, suggesting that the air in the city of Toronto during the experiment was severely polluted. (2) The variation of the electrical conductivity corresponded significantly to those of pollutant concentrations for most timescales, characterized by a common variance-contributing scale range from a few hours to a few weeks in the variance spectra. (3) The variations of both electrical conductivity and pollutant concentrations were contributed mainly by daily changes of hourly averaged values and weekly changes of daily averaged values, coinciding with the daily and weekly cycles in the city's traffic and industrial activities. (4) The electrical conductivity correlated negatively with pollutant concentrations for most timescales. However, the correlations were contributed mainly by weekly changes of daily averaged values, different from the variation contributions of these variables. This suggests that the electrical conductivity is poorly synchronized with pollutant concentrations for the timescales smaller than diurnal component, which could be expected to introduce noises if the correlations between the electrical conductivity and pollutant concentrations at the scales smaller than diurnal component are pursued. ¿ American Geophysical Union 1996