Calf Muscles. 1  The calf muscles are six in number: the gastrocnemius, the soleus, the popliteus, the tibialis posterior, the flexor digitorum longus, and the flexor hallucis longus. 2  The gastrocnemius and the soleus run between the knee and the ankle. 3  One of the calf muscles, the soleus, has a special ability.
Ozone Pollution. Ground level or bad ozone is not emitted directly into the air, but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight.
Ozone levels above a minimum concentration can cause pollution and harmful health effects. Ozone is created when volatile organic compounds (VOCs) react with oxygen in the atmosphere. The electrical energy in lightning can create ozone from oxygen molecules. The Earth's ozone layer was significantly reduced by CFCs, found in aerosol spray cans and other products.