Date of Award


Document Type



Environmental Science

Thesis Advisor

Lee A. Newman


Recently, noise pollution has been recognized as a profound global issue with serious consequences for ecological, human, and animal health. Only one study has documented a health impact of noise on plants, noting expression of oxidative stress regulators to combat reactive oxygen species (ROS) generation in plant cells. Anthropophony (human-generated sounds) is the major cause of noise pollution, particularly road transport anthropophony (RTA) from vehicles and traffic congestion. Two plant species, Buxus microphylla (Wintergreen boxwood) and Juniperus squamata (Flaky juniper), were selected based on their use as vegetative barriers to control RTA. A field recording of RTA and corresponding sound pressure level measurements were taken alongside the U.S. 101 freeway in Woodland Hills, CA. This recording was looped to exposed plants (n=5) through a studio monitor at 73.5 dBA (±1 %) for 24 hours in a soundproof room. Control plants (n=5) were left in silence in the soundproof room for 24 hours. Leaf tissue was harvested and analyzed via colorimetric UV/Vis spectrophotometry for total polyphenols, an oxidative stress regulator. It was hypothesized that RTA-exposed plants would express increased total polyphenols levels compared to non-exposed plants. The mean net total polyphenols content was not significantly different between exposed and control boxwoods (p = 0.998) or exposed and control junipers (p = 0.20 I). This indicates that RT A-exposed plants did not express increased total polyphenols levels. However, this study was the first to investigate potential adverse impacts of environmentally-relevant sound levels on plant species that may have a high daily noise pollution burden.