"As we rightly focus our energies on tackling climate change, we must be careful not to neglect the ozone layer and stay alert to the threat posed by the illegal use of ozone-depleting gases," UN Secretary-General António Guterres said in a statement on Monday.
"The recent detection of emissions of one such gas, CFC-11, reminds us that we need continued monitoring and reporting systems, and improved regulations and enforcement."
The ozone layer, made up of three types of oxygen atoms, is located approximately 15 kilometres above the earth and helps to protect the planet from ultraviolet rays that cause skin cancer, crop damage, eye cataracts and other issues.
But since the late 1970s, the ozone layer had been consistently thinning due to the overuse of chemicals called chlorofluorocarbons, reaching a crisis point in the 1990s when about 10 per cent of the layer had been eroded.
In 1987, UN members signed a treaty - known as the Montreal Protocol - aimed at phasing out ozone-depleting substances and developed replacements. According to the UNEP, the Montreal Protocol has successfully led to the removal of 99 per cent of chlorofluorocarbons, which previously existed in refrigerators, air-conditioners and other consumer products.
"The Montreal Protocol is both an inspirational example of how humanity is capable of cooperating to address a global challenge and a key instrument for tackling today’s climate crisis," Mr Guterres said.
"Under this international treaty, nations have worked for 32 years to slash the use of ozone-depleting chemicals, used largely by the cooling industry. As a result, the ozone layer that shields us from the sun’s harmful ultraviolet radiation is healing."
The ozone layer is also instrumental in curbing the effects of climate change, with the barrier stopping approximately 135 billion tonnes of carbon dioxide emissions from entering the atmosphere between 1990 to 2010, UNEP said.
Earlier this year, China came under fire for allegedly releasing large quantities of banned chemical Chlorofluorocarbon-11 (CFC-11) into the atmosphere, in violation of the UN treaty.