What is the difference between good and bad ozone?

Ozone gas is a compound made up of three oxygen atoms (O3). However, the effect this gas has on human health depends entirely on its location in the atmosphere. This means that ozone itself is not inherently "good" or "bad" by its chemical nature; rather, its location determines whether it acts as a protective shield for life or as a harmful pollutant for the respiratory system [1] [2].

Good Ozone in the Upper Atmosphere

Good ozone exists naturally in the upper layers of the atmosphere, at an altitude ranging from approximately 10 to 30 miles above the Earth's surface. This ozone plays a vital and critical role in protecting the planet, acting as a shield that absorbs a significant portion of harmful ultraviolet (UV) radiation from the sun [1]. If this layer is depleted by chemicals produced by human activity, the amount of UV radiation reaching the Earth increases, leading to serious health risks including skin cancer, cataracts, as well as a weakening of the efficiency of the immune system responsible for fighting diseases [2].

Bad Ozone at Ground Level

In stark contrast, ozone found near the Earth's surface is known as bad ozone or ground-level ozone. This ozone does not form naturally; rather, it is created as a result of chemical reactions between pollutants from car exhaust, factories, and other sources when they react with sunlight [1]. Ground-level ozone is considered the primary component of the smog seen in major cities, and its levels typically increase during the summer due to the increased intensity of sunlight that stimulates these chemical reactions [1].

Health Effects of Ground-Level Ozone

Inhaling ground-level ozone poses a direct threat to vital respiratory system functions, as it acts as an irritant to lung tissue. Direct effects of exposure to this type of pollution include: coughing, throat irritation, and the worsening of chronic respiratory conditions such as asthma, bronchitis, and emphysema [1] [2]. It is essential to understand that repeated and continuous exposure to ground-level ozone may lead to permanent lung damage; children are considered the group most vulnerable to this risk because their lungs are still in stages of growth and development [2].

For further details on this topic, you can read our awareness guide on Ground-level ozone pollution: its impact on health and how to protect yourself (Arabic).

Managing Health Risks

If you notice the onset of persistent respiratory symptoms or a deterioration in an existing respiratory condition after exposure to environments with high air pollution, it is essential to consult a healthcare professional to evaluate the condition. You should avoid managing any acute respiratory symptoms through personal assessment alone, as those with lung diseases require close medical monitoring to ensure that no long-term damage occurs to lung function. Always remember that professional medical follow-up is the best option to ensure the safety of your respiratory system in areas with high pollution.

Medical references

• Ozone
• Ozone