disruption of the food chain; and 5) degradation of the global atmosphere and loss of
natural protective zones such as stratospheric ozone.
Many pesticides are volatile, and even those with low volatilities can be transported
in the atmosphere as residues bound to dust particles or as aerosols. Both the active
ingredient and formulation constituents can become air contaminants. Volatile com-
ponents and residues bound to dusts may rise high into the atmosphere, travel long
distances, and be deposited far from the point of origin through various deposition
processes. Raindrops have been shown to have pesticide components.^11Air PollutionWhen a pesticide does not turn up as a water contaminant, it is often because it
has escaped to pollute the air instead. While no less troubling than water contamina-
tion, air contamination is significantly less well characterized and addressed. The EPA
has stated that: ‘‘Off-target spray can affect human health and the environment....
There are thousands of complaints of off-target spray drift each year.’’^12 Though
equipment modification and avoiding dangerous weather patterns can minimize drift,
the EPA nonetheless notes that ‘‘some degree of drift of spray particles will occur
from nearly all applications.’’^13 Air contamination from drift is thus an inevitable
result of spraying and one to which regulatory programs are essentially unequipped
to respond.Vapor MovementA pesticide that has vaporized (evaporated) can be carried from the treated area by
air currents. Vapor movement, unlike spray or dust drift, is related to the chemical
properties of the pesticide. Unlike the drift of sprays and dusts that can sometimes
be seen during an application, vapor movement is not visible. Vapor movement can be
caused by vapor leakage. Fumigants and other volatile materials exert pressure on the
environment around them. Like air in a balloon, they are actively trying to escape.
Keeping pesticide containers closed or sealed can stop vapor leakage. Fumigation sites
must also be sealed properly to keep pesticides from leaking. Applying these materials
with vapor-tight equipment is important. Some herbicides in particular can volatilize
and move from a treated area, reducing control of the target weeds and increasing the
likelihood that non-target plants will be injured. Pesticide vapors inside a dwelling can
also cause injury, particularly if the occupants are sensitive.
Evaporation, while less obvious than drift, may actually be the largest single source
of pesticides in the environment.^14 Unlike drift, evaporation is not limited to sprayed
pesticides but occurs with liquid, powder, and granular pesticides as well. Once pesti-
cides evaporate, they become part of the atmospheric water cycle. The U.S. Geologi-
cal Survey states: ‘‘Nearly every pesticide that has been investigated has been detected
in air, rain, snow, or fog throughout the country at different times of the year.’’^15
Like water contamination, air and precipitation monitoring show that local air194 | Pesticides