The prevalence of indoor occupancy in human societies today bring with it considerable issues pertaining to the indoor environment of enclosed residential and commercial spaces. Indoor air quality is one of those aspects of indoor environment that requires attention as persistent exposure to poor air quality can cause allergenic, visual and respiratory problems for occupants, inhibiting productivity and well-being. Today’s air filtration marketplace includes products, offered in many configurations, that present various advantages and disadvantages when compared to other air filter offerings. There are also different types of media incorporating varying principles of particle capture, each with its own advantage when applied in a ventilation and air conditioning application. How can filter users differentiate manufacturers’ claims and make intelligent decisions as to what products are applicable to meet their needs? Historically, many depended upon test reports. Unfortunately, today’s testing laboratory methodologies may not give a true barometer of a filter’s performance over time, as these filters are not tested under real life conditions. While high-efficiency filters can adequately address airborne contaminants, it is at the cost of increased energy on the air conditioning system. In this study, a comparison (in-situ test) was made between mechanical fine V-Bank air filters (ePM1 55% / F7) and Electrostatic Precipitators (Polarized filters) on the pressure drop incurred while ensuring adequate removal efficiency and satisfactory air quality for occupants. It was found that over 7 months of measurement at the tested airflow, no measurable increase in pressure drop was observed for the specimen mechanical filter, while the ESP (polarized filters) saw increasing pressure drop as the study progressed.