Today, pesticides have been detected in the atmosphere throughout the country,
and a wide variety of pesticides are present in air, rain, snow, and fog. There is signif-
icant evidence that pesticides used in one part of the United States are carried
through the atmosphere and deposited in other parts of the nation and beyond,
sometimes in places where they are not even used. Even in the Arctic and Antarctic,
pesticides are found in the air, snow, people, and animals. The extent of atmospheric
pesticide contamination has not been adequately studied.
No one knows for sure just how many people nationwide have been sickened by
pesticide drift. The federal government doesn’t officially track such cases. But
researchers at the EPA and the CDC have estimated that there are more than 5,000
serious poisonings a year from accidental drift.^2What is Pesticide Spray Drift?Pesticide spray drift is the physical movement of a pesticide through air at the time
of application or soon thereafter to any site other than that intended for application
(often referred to as off-target sites). The EPA does not include the movement of pes-
ticides to off-target sites caused by erosion, migration, volatility, or contaminated soil
particles that are windblown after application, unless specifically addressed on pesti-
cide product labels with respect to drift-control requirements.How Does Spray Drift Occur?When pesticide solutions are sprayed by ground-spray equipment or aircraft, the
nozzles on the equipment produce droplets. Many of these droplets can be so small
that they stay suspended in air and are carried by air currents until they contact a sur-
face or drop to the ground. A number of factors influence drift including weather
conditions, topography, the crop or area being sprayed, application equipment and
methods, and decisions by the applicator.Air MovementBoth horizontal and vertical air movement can affect drift. Unless it is calm, most
pesticide applications are subjected to constant air movement. Indoors, heating and
air conditioning systems move air and can move pesticides. Outdoors, unpredictable
changes in air movement can cause spray drift at any time. Thus, wind direction and
speed directly affect the direction, amount, and distance of drift.The Impacts of Spray DriftOff-target spray can affect human health and the environment. For example, spray
drift can result in pesticide exposures to farmworkers, children playing outside, and
wildlife and its habitat. Drift can also contaminate a home garden or another farmer’s
crops, causing illegal pesticide residues and/or plant damage. The proximity of188 | Pesticides