Positive and negative emissions from cooling towers, part 2: Particulate matter

Wet cooling towers evaporate water to transfer waste heat to the environment. In the process, they also emit liquid water in the form of spray drift. These emissions dry in the atmosphere to form aerosol particles composed of impurities in the water. Emission factor guidance for cooling towers is provided by EPA AP42. Total emissions are a combination of spray drift and ambient aerosol passing through the tower. Net emissions take into account the scrubbing of ambient particles in the tower. We directly measured tower particulate emissions and ambient concentrations to determine the contribution of spray drift to tower emissions as well as scrubbing effect on ambient particles. Two companion papers describe the instrumentation and the spray drift measurements. Copyright © 2025 American Association for Aerosol Research