Tropospheric ozone is simply ozone that is located closer to the ground or at ground levels where it can come into contact with people or objects. While stratospheric ozone is generally considered to be a good thing that helps protect the planet from harmful ultraviolet radiation, tropospheric ozone is often considered very harmful. Generally, it is thought of as a pollutant.
While ozone is not created or emitted from any one source, it is a combination of factors that can lead to an increase of the substance close to the earth’s surface. Those factors include the burning of fossil fuels, particularly from automobiles, power plants, and manufacturers. Together, those emissions, typically nitrogen oxides, combine in the lower atmosphere where they interact with sunlight and hydrocarbons. Once those come together, ozone is often a natural result of some very unnatural processes.
Living tissue is, perhaps, the most important thing that is impacted by tropospheric ozone, especially for plants. Ozone can affect the ability of plants to allow carbon dioxide and water to diffuse into the tissue, stunting growth, and leading to an unhealthy plant. In people and animals, ground-level ozone has been blamed for respiratory problems, especially in those who are outside and exercise regularly.
Some types of non-organic materials can also react negatively to tropospheric ozone. This ozone problem has been credited with destroying materials such as nylon and rubber. The problem can be expensive and lead to premature aging of these materials, costing owners time and money to replace them before they otherwise would need replacing. Elastic materials can lose their elasticity and become very brittle because of prolonged contact with ozone.
Like the ozone in the stratosphere, tropospheric ozone does not tend to last very long and must continually be regenerated. The short lifespan, with a half life of 30 minutes or less, generally means there are days when ground-level ozone may not be much of a problem at all, and days when it may be a big problem. Generally speaking, even the time of day makes a difference, with low ozone more prevalent during the afternoon hours.
At the same time, this shortened lifespan means that if the emissions creating it are controlled, the tropospheric ozone will disappear relatively quickly. Cities that have ozone pollution problems could be clear of harmful levels of the material within days if the proper controls are put in place, or if people were to change their habits. While addressing these causes may be difficult, the nature of ozone indicates the problem will only be a temporary one when that change does take place.