What is Ozone?
Ozone (O3) is a highly reactive form of oxygen. At normal concentrations it is colorless and odorless. At high concentrations (often associated with thunderstorms or arching electric motors) it is an unstable bluish gas with a pungent odor. Ozone is a major component of photochemical smog, although the visibility reduction and odor resulting from smog are produced by other pollutants such as particulates and nitrogen oxides. Ground level ozone in high concentrations is considered an air pollutant, while stratospheric ozone in the upper atmosphere (12 – 30 miles above the ground) is critical for absorbing cancer-causing ultraviolet radiation.
There are actually two kinds of ozone in the atmosphere. Ozone high above the earth, known as the ozone layer and ground-level ozone. In recent years we have heard a lot about the depletion of the ozone layer in the stratosphere. This stratospheric ozone layer provides a protective barrier that blocks harmful ultraviolet radiation from the sun reaching earth. Stratospheric ozone is good and is essential for protecting life on earth. However, ozone at ground-level in the atmosphere is harmful. The concentration of ozone and other air pollutants in urban areas is typically known as smog. When people usually think about smog, they picture a thick brown layer over Los Angeles. They don’t usually think of a hot Midwest summer day with a lots of sunshine and a hazy blue sky. Unfortunately, ground-level ozone reaches unhealthy levels in urban areas throughout the Midwest. In northwest Indiana, unhealthy ground-level ozone concentrations are regularly a problem during summer months. Ground-lev
Ozone is necessary for life on earth, as we know it. In its proper place in the stratosphere (up high), ozone helps protect the earth from the sun’s harmful rays. But on the earth’s surface (down low) ozone can create serious health effects. Ground-level ozone is formed when nitrogen oxides (NOx) and volatile organic compounds (VOCs) come together in the presence of heat and sunlight. NOx is found in the exhaust from motor vehicles and other sources of combustion or industrial processes. VOCs come from a number of sources, including evaporation tanks. Ozone is the major ingredient of smog, a problem plaguing many of our cities in Texas.
• Ozone is a form of oxygen whose molecule carries three atoms instead of two. Ozone is found both in the troposphere, i.e. the lower 10 km of the atmosphere and in the stratosphere (10-50 km above the ground). Ozone is our shield against harmful ultraviolet radiation from the Sun, so we need ozone in the atmosphere to protect us. However, ozone at ground level is a pollutant. It can trigger breathing difficulties for human beings and damage to plants and crops and is one of the major ingredients of smog. Whether ozone is “good” or “bad” therefore depends on its altitude in the atmosphere. • 2. What is happening to the ozone layer? • The ozone layer has been under attack from chlorine (chlorofluorocarbon, CFC) and bromine (halon) compounds abundantly used in the past in products such as aerosol spray, can propellants, refrigerants, pesticides, solvents and fire extinguishers. When these substances reach the stratosphere, the ultraviolet radiation from the Sun causes them to break apart
Ozone is an odorless, colorless gas that is not emitted directly into the air, but created by a chemical reaction between two types of air pollutants – nitrogen oxides (NOx) and volatile organic compounds (VOCs) – in the presence of heat and sunlight. Many urban areas tend to have lower levels of ground-level ozone compared to rural areas because ozone is destroyed in a reaction with nitric oxide, which is released primarily from motor vehicles. Ozone is a regionally transported pollutant usually measured at rural and suburban locations upwind and downwind of sources of ozone precursors (NOx and VOCs). Ground-level ozone is different from “good” ozone, which occurs naturally in the sky about 10 to 30 miles above the earth’s surface. It forms a layer that protects life on earth from the sun’s harmful rays. Why is ozone an important public health issue? Symptoms of exposure to increased ozone concentrations vary among individuals and may include: coughing; nose and throat irritation; che
