A number of expressions originally derived from participles have become prepositions, and you can use these to introduce phrases that are not associated with the immediately adjacent noun phrase. Such expressions include concerning, considering, failing, granting, judging by, and speaking of. Thus you can say without fear of criticism Speaking of politics, the elections have been postponed or Considering the hour, it is surprising that he arrived at all. 4 participles as adjectives . But it is often hard to tell when a participle is an adjective, especially with past participles.
Linguists have a number of tests for confirming an adjective.
Can it be compared, as in We are even more encouraged now and The results are most encouraging. Can it be modified by very, as in They are very worried about this. Some adjectives pass more of these tests than others and are thus more purely adjectival. When used as adjectives, most participles pass all four tests, but modification by very is tricky. For more on this, see very and past participles.