Experimental study for the reproduction of particulate matter deposition on greenhouse plastic films

Atmospheric particulate concentrations have been increasing due to secondary particle emissions and climate change. The resulting particulate matter (PM) deposition may decrease the amount of sunlight reaching crops in greenhouses by reducing the light transmittance (LT) performance of the covering film. To determine the cause of this decrease in LT, indoor and outdoor experiments were performed. The indoor experiment comprised exposure to various PM and deposition types (i.e., wet and dry conditions), while the outdoor experiment comprised exposure to a natural environment while testing different film installation methods. These results showed that the decrease in LT through greenhouse films was related to PM conditions. Wet deposition of the ion component of PM caused a greater drop in LT than dry deposition. Additionally, the installation film angle, exposure period, and rainfall exposure of the greenhouse-covering material all significantly affected LT. The decreased LT in the indoor PM-generation experiment was similar to when films were exposed to natural conditions for more than 12 months. These results could assist the farmers in predicting covering materials LT decrease caused by PM and in strategically managing the plastic films of their greenhouses.