Despite low ozone values in 2025, there is no reason to panic, according to Senior Scientist Tove Svendby at NILU’s Department of Atmosphere and Climate.
September 16th is the UN’s International Day for the Conservation of the Ozone Layer. On behalf of the Norwegian Environment Agency, NILU measures stratospheric ozone and UV radiation every year. The most recent report, which applies to 2025, was recently published. It shows that ozone values were generally low last year.
“A strong polar vortex led to low ozone values and high UV radiation in Norway in 2025, especially early in the year. In March last year, we measured at our station at Kjeller outside Oslo the lowest values we have recorded since measurements in the Oslo area began in the 80s,” says Senior Scientist Tove Svendby, who is the lead author of the report from NILU.
Common with variations
However, Svendby is not particularly worried about the state of the ozone layer.
“It is not unusual for it to vary a lot from year to year. It is not a drastic decline and generally speaking, the ozone layer is improving. In 2024, the ozone layer was thicker than normal. So far this year, the values have been fairly normal,” says the researcher.
She explains that stratospheric ozone is formed high up in the atmosphere near the equator and moves with the air currents to the rest of the globe. The thickness of the ozone layer is strongly linked to weather systems in the stratosphere and meteorological conditions. The further you are from the equator, the greater the chance of large variations in the thickness of the ozone layer.
High UV Radiation Alerts
The main reason why scientists are paying so close attention to the ozone layer is the risk of high UV radiation.
“When the ozone layer is thin, more harmful UV rays come through the atmosphere and hit us. How strong this UV radiation is will also depend on the amount of clouds and how high the sun is in the sky,” says Svendby.
NILU sometimes sends out a warning that the UV radiation is extra high. Then it is recommended to seek shade and use sun protection such as sunscreen with a high factor, sunglasses and a hat.
You can check the UVI warning yourself on https://uv.nilu.no
The Norwegian UV network consists of nine monitoring stations, where three stations are operated by NILU and six stations belong to the Norwegian Radiation and Nuclear Safety Authority (DSA). Real-time data from the measurement network can be found here.
Celebrating the Montreal Protocol
Much of the improvement in the ozone layer since the 80s is due to the Vienna Convention for the Protection of the Ozone Layer. It was adopted in 1985. At that time, the nations of the world came together and agreed to take measures to protect people and the planet from harmful UV radiation that penetrates a depleted ozone layer.
Among other things, the convention led to the signing of the Montreal Protocol on September 16th, 1987. There was agreement on the phasing out of ozone-depleting and long-lived chlorofluorocarbons (CFCs), which were used in refrigerators, spray bottles and foam, among other things.
On September 16th, 2009, the Vienna Convention and the Montreal Protocol became the first treaties in the history of the United Nations to achieve universal ratification.
The United Nations International Day for the Conservation of the Ozone Layer is laid to the date of the Montreal Protocol to also mark and celebrate it. This year’s theme for Ozone Day is Global Action for a Cooler Planet.
The improvement of the ozone layer is a good example of what we can achieve globally, if we listen to scientists and follow up with the measures that are required.