Choke breath until symptoms lack of oxygen is a headache, clumsiness. High pressure, high heart rate. If concentrations as high as 12 percent or more is senseless in 1-2 minutes.
Shortness of breath or difficulty breathing, hypoxia were headache, dizziness, high blood pressure, heart rate increased. If the concentration is as high as 12 percent or more would lose consciousness within 1-2 minutes.
Breathing, breathing difficulties, lack of oxygen, until symptoms are headaches, dizziness, high blood pressure, increased heart rate. If a high concentration of 12 or more 1-2 consciousness within minutes.