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.
Secondary pollutants include: 1  Particulates created from gaseous primary pollutants and compounds in photochemical smog. Smog is a kind of air pollution. 2  Ground level ozone (O3) formed from NOx and VOCs. Ozone (O3) is a key constituent of the troposphere. 3  Peroxyacetyl nitrate (C2H3NO5) - similarly formed from NOx and VOCs.