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.
There are many types of footwear that are designed to protect your feet. Steel toe footwear protects your toes from falling objects and from being crushed. Metatarsal footwear have special guards that run from your ankle to your toes and protect your entire foot. Reinforced sole footwear have metal reinforcement that protects your foot from punctures. Latex/Rubber footwear resists chemicals and provides extra traction on slippery surfaces.