A method of reducing contaminants in air, including applying titanium dioxide-containing growth media to at least one of a Myrtus communis plant root, stem, and leaf, and growing the plant. The growth media is a liquid growth media, a gel growth media, or both. The plant is then exposed to contaminant-containing air. The contaminant is CO2, SO2, formaldehyde, CO, benzene, toluene, xylene, ethyl benzene, or a combination thereof. The contaminant concentration in the air is reduced relative to a contaminant concentration in the air prior to the exposing. A plant portion having a portion of a Myrtus communis plant comprising an infused titanium dioxide is also described. The portion is at least one of a root, stem, or leaf. In a closed environment, the plant portion reduces the concentration of a contaminant in the air in the closed environment.