Why ozone is harmful in the troposphere

A different range of wavelengths of ultraviolet nm are strongly absorbed by ozone, which breaks down as a result and reforms into molecular oxygen again. The higher up in the atmosphere you go, the thinner the air is, and thus the less oxygen there is to absorb the nm ultraviolet to form ozone.

This means that ozone amounts tend to decrease as you go higher. The lower down in the atmosphere you go, the more oxygen the ultraviolet has to pass through to get there, and the greater the chances are that it has already been absorbed to create ozone somewhere higher up. This means that very low down, the ozone concentrations tend to be lower. From roughly 12 to 30 km, the two tendencies balance out, and the highest ozone concentrations are found there, in what is called the "ozone layer".

This is why the ozone layer exists in the lower part of the stratosphere. Code for developers. Systems Status. Legal notice. Creative commons license. CMS login. Toggle navigation Skip to content. Advanced search A-Z Glossary. Error Cookies are not enabled. You must enable cookies before you can log in. Login Name. Forgot your password? You are here About ozone Good and bad ozone. Good and bad ozone PDF. This website has limited functionality with javascript off. Some migrates down from the stratosphere.

But neither of these sources contributes enough ozone to be considered a threat to the health of humans or the environment. Most of the ozone that is found near the ground comes from vehicle exhaust and emissions from factories, power plants, and refineries.

Since , the amount of ozone near the Earth's surface has more than doubled due to more automobiles and industry. Unlike most other air pollutants , ozone is not directly emitted into the air. Tropospheric ozone is formed by the interaction of sunlight, particularly ultraviolet light, with hydrocarbons and nitrogen oxides , which are emitted by automobile tailpipes and smokestacks.

In urban areas, high ozone levels usually occur during warm summer months. Typically, ozone levels reach their peak in mid to late afternoon, after exhaust fumes from morning rush hour have had time to react in sunlight. A hot, sunny, still day is the perfect environment for the production of ozone pollution. At the end of the day, as the Sun starts to set, the production of ozone begins to subside.