## 2 Materials and Methods  
For the purposes of this experiment, a glass enclosed terrarium with dimensions of 17.75 in \(\times\) 8.75 in \(\times\) 13.75 in and an internal volume of 1853 in [3] was used (Figure 1). A one-inch diameter opening was created in an upper side wall of the terrarium to facilitate the introduction of pollen into the terrarium. The upper portions of the terrarium were sealed with tape. The terrarium was placed on the counter of the laboratory so that it could be lifted off the table for setup and to collect data between different testing conditions. A Brushless DC fan (DC12V, 0.06A) controlled by an on/off switch was positioned inside the terrarium below the one-inch opening (Figure 2). As shown in Figure 2, a small plastic cup containing the weighed pollen sample was inserted into the terrarium opening, held in place with tweezers, and carefully agitated above the fan to evenly disperse the pollen into the terrarium. A Young Living ultrasonic type diffuser, model Desert Mist(tm), was placed into the terrarium (Figure 3) and cycled on/off depending on the experimental protocol as described below. The Desert Mist(tm) diffuser has three run modes: high mode (runs for 5 h continuously), low mode (runs for 8 h continuously), and intermittent mode (1 min on/1 min off for 10 h). The diffuser was operated in high mode during all experiments. 100 mL of reverse osmosis water was accurately measured at the beginning of each experiment and added to the diffuser reservoir. For all experiments that required essential oils, ten drops were added to the diffuser reservoir after RO water was added. Figure 1: Enclosed Glass Terrarium. Figure 3: Desert MistTM Ultrasonic Diffuser. Figure 2: Experimental setup with terrarium opening and pollen cup over the fan. Microscope slides coated with a dielectric silicone compound were used to collect the pollen grains that would fall to the terrarium floor. Three slides were positioned in the center of the terrarium between the fan and the diffuser for each experiment. At the conclusion of each test, the slides were removed and the pollen grains from three locations on each slide (left, center, right) were counted and recorded. Three types of pollen were examined for suitability for this experiment: lodgepole pine, _Pinus contorta_ (Canadian Pine Pollen Co., North Vancouver, BC, Canada); pecan, _Carya illinoensis_ (Polysciences, Inc., Warrington, PA, USA); and ragweed, _Ambrosia artemisifolia_ (Polysciences, Inc., Warrington, PA, USA). These types of pollen were readily commercially available in the necessary quantities. Ragweed pollen is a common allergen, however it did not disperse evenly and clumped on slides, which prevented accurate and unbiased counts of deposited ragweed pollen, so we discontinued experimentation. Both lodgepole pine pollen and pecan pollen were chosen because their size made accurate counts possible and because of their even distribution in the terrarium and on the slides (Figure 4). The pollen was weighed in the following amounts: 0.03 g, 0.05 g, 0.07 g, 0.09 g and 0.11 g. After the pollen was carefully released over the fan, the small plastic cup which had contained the pollen was weighed again to determine how much pollen was introduced into the terrarium. All tests were performed in triplicate. Three different diffuser conditions were tested for each weight of pollen. First, pollen was introduced into the terrarium with the diffuser present but turned off. Second, pollen was introduced into the terrarium with a diffuser operating on high mode that contained 100 mL of RO water only. Finally, pollen was introduced into the terrarium with a diffuser operating on high mode and that contained 100 mL of RO water with ten drops added of one of the following Young Living essential oils: lavender, Thieves(r) (a blend of lemon, clove, cinnamon bark, eucalyptus radiata, and rosmear), Citrus Fresh(tm) (a blend of orange, grapefruit, mandarin, tangerine, lemon, and spearmint).