Marta Cecilia Guapacha, the head nurse at the town's San Francisco hospital, says that she has treated many cases of poisoning, skin rashes and respiratory and eye problems which she believes to be caused by herbicides sprayed by police crop-dusting planes.

ECONOMIST: Putumayo��s tense wait for the arrival of Plan Colombia

Delta Air Lines was founded in the city of Macon, Georgia (originally as a crop-dusting company called Huff Daland Dusters) and later moved its headquarters about 85 miles north to Atlanta in 1941 (after running its first passenger flights under the name Delta Air Service in 1929).

BBC: Why is Atlanta the world��s busiest airport?