Abstract
The primary objective of this study was to determine the effect of different ventilation systems and application pressures on dermal and respiratory exposure. Three types of ventilation were evaluated: low velocity unidirectional (uni; <0.5 to 2.0 m/s), multidirectional (multi), and no ventilation (none). Under each condition, two application pressures were utilized: 284 kPa (40 psi) and 841 kPa (120 psi). Six workers were monitored by the traditional patch technique and personal air sampling during greenhouse handgunning applications. A commercially available fluorescent tracer was employed as a surrogate for pesticides. The magnitude of dermal exposure varied by ventilation type (multi > none > uni). Respiratory exposure also varied by ventilation type, but with a different pattern (none > > multi > uni). Application pressure had the greatest effect on respiratory exposure: low pressure (40 psi) values were less than high pressure (120 psi), regardless of ventilation type. The droplet size distribution created by the nozzle appears to have been the primary factor affecting both dermal and respiratory exposures. As application pressure increases, droplet size decreases, resulting in dramatic and consistent increases in both dermal and respiratory exposure. Results indicate that properly trained applicators can reduce their exposures by using unidirectional ventilation to their advantage (i.e., keep air flow at their backs, allowing spray mist to move away from them) and reducing the application pressure so that larger droplets are formed and fall out of the airspace quickly.
