Harmful refrigeration and air-conditioning gases that were banned from import nearly two years ago are still in use and threatening the ozone layer, an expert says.
The UAE prohibited the import of chlorofluorocarbons (CFCs) in January last year.
But Stuart Fleming, the managing director of a company that recycles refrigerants, said companies were still using the gases.
"I am not sure where it comes from," Mr Fleming said. "However, unfortunately, certain organisations are bringing it in."
The ozone layer, about 16 kilometres above the Earth's surface, absorbs ultraviolet radiation from the sun, protecting people and the environment from its harmful effects.
The layer has reduced in density, especially above the Antarctic, because of the past use of certain chemicals.
International efforts to reduce the use of CFCs have on the whole been successful and emissions have been declining.
But because ozone-depleting substances take an average of four decades to break down once they have been released, they continue to have a negative effect on the ozone layer.
Scientists expect the layer to recover by the middle of this century. Mr Fleming said more needed to be done to ensure rules on ozone-depleting gases were followed.
The UAE is a signatory to the Montreal Protocol, a global treaty to ensure such substances are replaced with safer substitutes. CFCs were among the first gases to be targeted by this treaty.
Responsibility for implementing the law is shared by the Ministry of Environment and Water and local authorities.
"It is a big task and they have a long way to go," said Mr Fleming, whose company, EnviroServe, recovers, cleans and resells refrigerants.
Companies may still be using CFCs because they are cheaper, or because they are thought to be more effective in deep freezing for commercial use and ice rinks.
"This gas is very good for freezer and refrigeration equipment," said Mr Fleming.
Venting, where refrigerant gases are released into the atmosphere by companies that maintain air-conditioning equipment, is another threat to the ozone layer. Refrigerant gases should be collected and stored safely at the end of their life cycle.
Venting is difficult to monitor because of the number of companies in the market.
Hydrofluorocarbons (HFCs) are among the safest alternatives to CFCs.
But while they are more ozone-friendly, HFCs can still contribute to climate change.
Narciso Zacarias, an engineer at the environmental department of Dubai Municipality, said it had recently begun controlling imports of HCFCs (hydrochlorofluorocarbons), a subclass of CFCs, which also damage the ozone layer.
Importers need to obtain clearance from the municipality to bring them in, Mr Zacarias said.
"The environment department issued revised guidelines in 2010 and a circular in July 2008 requiring owners or operators of any stationary or mobile air-conditioning or refrigeration system, including service providers, to implement adequate equipment maintenance, prohibit the venting of refrigerants and use of alternative substances," said Mr Zacarias.
An official at the Environment Agency - Abu Dhabi said monitoring CFCs was the responsibility of the Ministry of Environment and Water.
The Ministry of Environment and Water declined to comment.
Mr Fleming said authorities may be better off focusing on small operators, who are usually more likely to resort to venting.
He said most international refrigeration and air-conditioning management firms, and shipping companies, already adhered to international regulations.