As stated in preamble to the 1997 PM National Ambient Air Quality Standards ( 40 CFR 50 , 1997 ) , the consistency of the results of the epidemiological studies from a large number of different locations and the coherent nature of the observed effects are suggestive of a likely causal role of ambient PM in contributing to the reported effects , which include premature mortality .
As a result of these findings , an action plan is being created to reduce ambient PM .