Could you find a town or city in the USA where people can live free of
pesticides and fertilizers.(green community, free of chemicals) A
community that would be healthy for people that have chemical
sensitivities.

This article may be of interest to you:

http://www.thegreenguide.com/doc.mhtml?i=107&s=cities

I doubt such a place exists because if it did I would have found it by
now!!! I'm not sure you will appreciate the angle I am taking on this,
but, being chemically sensitive myself here are a few thoughts.

(1) if someone was looking for a community where there are no
pesticides the only one I know of is in the desert with the other
chemically sensitive who are living there in their trailers.   See: 
http://www.emagazine.com/view/?1003
    and
http://www.beyondpesticides.org/infoservices/pesticidesandyou/Winter%2098-99/The%20Dispossessed%20(Book%20Review).pdf

     and
http://www.theworld.com/~habib/thegarden/mcs/resources.html
      and
http://www.talkingleaves.org/f98dispossessed.htm

(2) I once read a book (sorry, can't remember the name) where they
attempted to build an apartment complex where they could house the
chemically sensitive safely (California somewhere) but it did not
really work as everyone was so different as to their sensitivities
that they could not move the project into full operation.

(3) I think you are looking for a "more normal" community.  Absent a
whole community--I once read about a family who build a huge tree
house that rambled through the trees and that worked for them.  Some
people move to the ocean where there are off shore breezes with
minimal pollution.

(4) My most successful action has been to surround myself with
negative ionizers, get on an expensive alternative health program of
diet and vitamins and gain full knowledge of what and what not to put
in my body, live in a countrified place which does not contain the
toxic air of a city, and dream of the day I may be able to buy an
infra-red sauna and sweat out toxins and heavy metals that most likely
play a hand in this conditon.  I have had to make the best of it in
this fashion while working 40 to 60 hours a week...up from a time in
1998 when I thought I had worked my last day at the office.  The
planet is horribly polluted.  If I had a billion dollars I could
afford to design and build a huge bubble that served my
needs!!!!!!!!!!!!!!

(5) I am not sure how to pre-qualify a place to live.  I once thought
that Nova Scotia sounded good until I read that even the tourists
could not stand all the pesticied they put on their crops.

Good luck in your quest.

An area away from farming with unused wilderness. Dont hold a candle
hoping to find utopia, creating ones own will raise immune function.
Rather than look outside for help, go within. Searchers are everywhere
looking for answers from others. "communities of eden" by a berkley
professor[cant remember name] is a good study of communes, written in
the 70's. A good homeopath specialising in toxicoly may be able to
remove toxins from the body, relying just on herbs like milk thistle,
dandelion etc is not usually enough