A higher than normal level of carbon dioxide in the blood. This suggests that ventilation in the air sacs of the lungs (alveoli) is inadequate possibly because the sensitivity of the respiratory centre to raised CO2 levels has been affected. In health, hypercapnia always causes an increased rate and depth of breathing.
The treadwear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test track. A tire graded 200 would last twice as long on the government test course under specified test conditions as one graded 100.
Barefooted person leaving footprints behind. Barefoot is the most common term for the state of not wearing any footwear. Wearing shoes and keeping the feet protected against the environment has been the normal state in urbanized civilizations since early antiquity, and can be regarded as a convention in most cultures.