Almost every person on Earth has heard about the terrible ozone holes. It would seem that the more ozone - the better! Fewer holes, which means less chance of excess UV radiation. However, this is not quite true. The ozone layer, which protects us from the Sun, is in the stratosphere, but the accumulation of this substance in the surface air is bad. The amount of "bad" ozone in the Northern Hemisphere has increased dramatically over the past 20 years, new research has shown.
Scientists conducted the first-ever study using ozone data collected from commercial aircraft. So they found that levels of this substance in the lowest part of the Earth's atmosphere have increased throughout the Northern Hemisphere over the past 20 years. Researchers were surprised that this happened even despite tightening emission controls.
Tropospheric ozone is located 12-15 kilometers above the ground. It is a greenhouse gas and air pollutant. In high concentrations, it damages the lungs as well as harms plants.
Finding elevated levels of ozone over the Northern Hemisphere means that when humanity tries to limit pollution locally, it may not work, scientists said.
Previous studies that monitored ozone levels in the Northern Hemisphere were not entirely accurate, as there are very few long-term monitoring tools available at this time. This is why researchers have turned to aviation data.
The authors used the data obtained to calculate changes in tropospheric ozone from the mid-1990s to 2016 over 11 regions of the Northern Hemisphere. They found a general increase in ozone across all regions, including four in mid-latitudes, two in the subtropics, two in the tropics, and three in the equatorial regions. On average, over a decade, average ozone values have increased by 5%.
To understand what is causing changes in ozone levels, the researchers looked at data on emissions from one of the main precursors of ozone, NOx. The model showed that the increase in anthropogenic emissions in the tropics is likely to be responsible for the observed increase in ozone in the Northern Hemisphere.
Now the team of scientists wants to better study and understand how the precursors of ozone in different regions can affect its level in very different areas.