Iodine concentration in the atmosphere tripled between 1950 and 1990, analysis of Alpine ice in Europe has shown. While this increase in the level of iodine partially offsets the harmful ozone in the atmosphere, it is still not enough to counter the amount of the pollutant that human activities produce.
Ozone is a greenhouse gas, but also a pollutant. Surface or ground-level ozone is an irritant that forms just above the Earth's surface. It is produced when volatile organic compounds (VOCs) and nitrogen oxides (NOx) react in presence of stagnant air and sunlight. VOCs and NOx can come from natural sources or through human activities.
Exposure to ozone can significantly impact human health. The pollutant is linked to premature mortality and asthma symptoms in humans. It can also significantly impact vegetation on earth.
In the new study, published in the journal Proceedings of the National Academy of Sciences, scientists from the University of York, Desert Research Institute and Université Grenoble Alpes found that iodine levels have increased threefold over the past century.
According to researchers, iodine concentration started to rise after the Second World War with the speeding up of industrialisation in many countries, which led to a growth in electricity generation and vehicle production. Motor vehicles and power plants emit NOx that increases the proportion of harmful surface ozone. This ozone reacts with seawater iodide to release volatile inorganic iodine into the atmosphere.
The researchers said that atmospheric iodine works as a significant sink of tropospheric ozone, and destroys this harmful pollutant.
"Iodine's role in human health has been recognised for some time—it is an essential part of our diets," said Professor Lucy Carpenter, from the University of York's Department of Chemistry.
"Its role in climate change and air pollution, however, has only been recently recognised, and up until now, there have been no historical records of iodine in populated regions such as Europe."
Professor Carpenter says it is a bit difficult to access this type of data, and therefore current climate or air quality models don't take into consideration the impact of atmospheric iodine to predict future environmental changes.
The study sheds new light into the delicate balance of ozone in the atmosphere, suggesting that more ozone produced due to human activities leads to the release of more iodine from the ocean, which eventually helps to negate the harmful ozone.
The researchers also revealed that the levels of surface ozone over much of the Atlantic Ocean and Europe have now stabilised, although they are still growing over other regions.
Privilege escalation bug already being exploited in the wild
NASA's Voyager 2 probe set to reveal secrets of space beyond the heliosphere as it goes interstellar
The probe is now more than 18 billion kilometres from Earth, with equipment enabling it to reveal some of the secrets of interstellar space
Four glaciers located west of massive Totten glacier have lost almost three metres of ice in height since 2008
Ceres, located in the asteroid belt, has a carbonaceous-rich upper crust, SwRI study claims