Water and plants absorb 55% of the carbon dioxide and pollutants introduced by humans into the atmosphere (Riebeek, 2011). This study hypothesizes that outdoor air filtration systems consisting of combinations of specific plants and saturated hydrogels are effective in increasing indoor air quality (IAQ) by decreasing airborne pollutants coming in via outdoor urban environments. Various plant types are analyzed to compare their efficiency in reducing air pollutants. From these, the Crassulacean Acid Metabolism (CAM) type plants were found to be the most efficient. Saturated hydrogels configured in a matrix to allow air to pass through were also found to absorb volatile organic compounds (VOCs) and particulate matter (PM10 and PM2.5). The study was conducted in a hot arid climate in Tucson, Arizona, USA. The results revealed a lowering of dry-bulb temperature in the daytime hours via evaporative cooling, an increase in relative humidity levels to 46% on average, and reduction in daytime levels of VOCs, CO2, and PM10 and PM2.5. This study, therefore, has significant implications for the future design of outdoor air filtration systems that can be combined with natural ventilation strategies for optimum IAQ.