Average particle concentrations on the top surfaces of leaves were higher than those on the bottom surfaces. This disproves one of the hypotheses, that concentrations on the bottoms would be higher than those on the tops. The reason for this is most likely because the amount of particles settling on the top is greater than the amount being caught in the stomata.

Particles on the bottom surfaces of leaves were shown to be smaller than those on the top surfaces. This is supportive of one of the hypotheses. Also shown was that particles on the surfaces of suburban leaves were the largest, followed by urban leaves, and then by rural leaves. The reason for this may be because some of the smaller particles from the city are carried out to the rural areas by wind, while the larger particles are deposited closer to the city (in the suburban areas). The urban leaf probably has a different particle diameter distribution causing its median Dave to be in between the others.

The concentrations decrease from urban to suburban to rural, as predicted. This points towards the ability of leaves to be used to monitor airborne particulates.

Different leaf types have been studied, and have quite different surface properties. It requires much further work to determine if one type is best for the purposes of this research.

This is not proof that leaves can be used to replace the filter sampling widely used. However, this method looks promising. Further analysis of sizes and chemical composition of the particles and comparison with results from filter samples is required for proof of this method’s accuracy. This will be the subject of future research.