Vegetative environmental buffer (VEB) has been proposed as a potentially cost effective strategy for reducing multiple air pollutants from livestock facilities. However, effectiveness of VEBs is highly variable and usually depends on site specific design. Lack of information on performance and technical guidelines are barriers to adoption of VEBs. The objective of this study was to investigate the effectiveness of VEBs under various design parameters for mitigating emissions of multiple air pollutants including NH3, H2S, N2O, CH4, CO2, VOC, odor and PM10, from a research swine barn. Three scenarios of VEBs of Red Cedars were established with one background scenario (without VEB): one row of trees at 8 feet height, one row of trees at 12 feet height, and three rows of trees at 8 feet height. The line of the VEBs was 120-150 feet away from the exhaust fans of the swine bam. Six air sampling locations were set up, at 10, 110, 160, 210, 260, and 310 feet away from the exhaust fans. The results showed that the 3-row-8' VEB reduced downwind H2S and NH3 concentrations by up to 60% and 48% respectively. VEB was also effective in reducing downwind concentrations of N20, CH4 and CO2. No reduction was observed for downwind VOC and odor measurements. A single row of VEB may generate unwanted turbulence that can affect the effectiveness of reducing downwind concentrations of air pollutants. In order to secure the expected effectiveness, an adequate thickness of the VEBs is very important.