Attributes . All Alarms Adjustable, Low O2 19.5%, High O2 23.5%, CO 35 ppm Warning, 70 ppm Danger, H2S 10 ppm Warning, 20 ppm Danger, CI2 0.5 ppm Warning, 1.0 ppm Danger, LEL 10% Warning, 20% Danger, VOC Varies by Gas Type . Names