Smog weakens the trees so that they are more susceptible to beetles and diseases. This map shows how the mountains combine with a low altitude inversion layer in summer to trap air pollution. Ocean breezes push the pollution back into the San Gabriel Valley and up against the mountains. Spectral selectivity methods could be applied to this problem as a way of measuring the extent of the damage over time. Infrared imaging provides a means for measuring the vitality of the forest.
Healthy vegetation reflects more infrared than dead and dying vegetation.
Aerial survey methods using infrared imaging methods are well developed and could be used to monitor this condition. Unfortunately aerial surveys are very expensive to conduct. The goal here will be to develop a ground based method using spectral selectivity methods and digital imaging which is capable of measuring forest vitality. An inexpensive ground survey method would be a valuable tool for monitoring the impact of pollution. This topic is not yet complete.