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.
Traffic is the main source (>50%) of ozone precursors. It may sounds curious, but it is a fact that most of the times ozone levels are higher in rural areas than in cities. This is sometimes called the 'ozone paradox'. Ozone can be degraded by the compounds (NOx) by which it is also formed. This degradation occurs more often in cities than in rural areas, because there is more NO in cities (see further).