Chemicals are all around us: in the air, in the Earth’s crust, in the ocean.
Though they are sometimes depicted as bad, they are essential in many applications, including pharmaceutical and semiconductor manufacturing. In fact, the same chemical might be beneficial in one context but harmful in another.
For example, ozone in the stratosphere protects us from harmful UV solar radiation but at ground level contributes to lung damage. Here we consider another chemical—benzene—commonly used in the manufacture of synthetic products such as nylon but, unfortunately, also found in some hair products.