Fig. 1.

Schematic of collection bag. a First-generation yellow, 10-L bag. Bag outlet was located 4 cm above the bag’s bottom. b Second-generation drab green, 10-L bag. Bag outlet was located 10 cm above the bag’s bottom. 0.5-L volume increments were demarcated on the bag. c Third-generation drab green, 6-L bag. Bag outlet was located at the bag’s bottom, and a 15.5° slope was heat sealed onto the bottom of the bag. 0.25-L volume increments were demarcated on the bag