A LOW-SAMPLE-CONSUMPTION DRY-PARTICULATE AEROSOL GENERATOR FOR USE IN NOSE-ONLY INHALATION EXPOSURES

Abstract

Generation of stable, low concentrations of dry particulates in nose-only chambers can be difficult, and if the supply of particulate is limited, the problems can be greatly increased. One problem is that many dry-particulate aerosol generators have higher aerosol output or airflow than can be accommodated by a nose-only inhalation chamber, requiring much of the aerosol generated to be diverted to waste. Another problem is that mixing vessels used to modulate the fluctuating output from aerosol generators can cause substantial wall losses, consuming much of the aerosol generated. To overcome these problems, a low-consumption dry-particulate aerosol generator was designed to deliver stable concentrations in the range of 1-50 mg/m 3 to a nose-only chamber without the need for diverting any of the generator output. The generator air flow of 10-15 L/min supplies all the air to the exposure chamber, with a 6-h exposure at 10-15 mg/m 3 consuming as little as 200-300 mg of particulate. The generator uses the principle of a carpenter's chalk line to pick up particles from a small reservoir, carry them out through an orifice, and past an air jet, where the particles are blown off the string.