A 24-hour air sample collection system

Increasing interest in gas emissions from animal agriculture operations may lead to development of new mitigation practices that will need to be field tested. A proposed protocol recommends collecting air samples over a 24-hour period. This report describes the design, performance and results from initial tests of a portable system for filling 50 L air sample bags over 24-hour sampling periods. Two bag filling schedules were tested, filling a sample bag 4 seconds every minute and filling the bag for 4 minutes every hour. The bag sample concentrations were compared to semi-continuous sampling system concentrations. The initial tests of a 24-hour sampling system indicate that the sampling system was able to reliably fill 50 L sample bags over a 24-hour period. The initial gas concentration results indicated that filling the bags for 4 minutes every hour were more consistently similar to the semi-continuous concentrations than filling the bags for 4 seconds every minute. Additional studies are needed to assess alternative bag filling schedules for collecting representative air samples over 24-hours.