Ozone is a pale blue gas that is present in low concentrations throughout the Earth's atmosphere. At ground level, ozone is an air pollutant; in the upper atmosphere, it is helpful in preventing ultraviolet light from reaching the Earth's surface. Ozone is made up of three atoms of oxygen. Two of these atoms form the type of oxygen we breathe. The third oxygen atom can detach from the ozone molecule and attach itself to other molecules. Therefore, it can react with other substances.
Since ozone's chemical properties allow it to react with other substances, it can not only react with materials outside the body, but it can react with similar organic material that makes up the body and become potentially harmful to your health. When high concentrations of ozone are inhaled, it can damage the lungs. Even low amounts of ozone can cause chest pain, coughing, shortness of breath, and throat irritation. Contrary to what many manufacturers of ozone generators say, ozone could possibly worsen chronic respiratory diseases such as asthma, and it could also hinder the body's ability to fight respiratory infections. As with many things, people's susceptibility to ozone varies. Whether or not you have respiratory problems, being exposed to ozone can cause difficulty breathing. If you exercise in an ozone generated environment, you could be breathing greater amounts of ozone, causing even more respiratory difficulty.