Cities across the Middle East are being choked by air pollution as rapid development leads to a huge increase in the number of cars and energy production.
Today is World Environment Day, which this year is focusing on air quality. The topic is particularly important for the region, where, according to World Health Organisation figures, air pollution kills half a million people every year.
In a report using satellite data recorded between June and August last year, Greenpeace named Dubai as among 50 global hot spots for the presence of nitrogen oxides, along with seven other Arab cities: Al Ahmadi in Kuwait; Baghdad; Cairo; Doha; Erbil in Iraqi Kurdistan; Jounieh in Lebanon and Riyadh.
Elevated levels of nitrogen dioxide in the air can cause damage to the respiratory tract, making people vulnerable to infections and asthma. Long-term exposure can cause chronic lung disease.
The Greenpeace report also highlighted that hot spots for nitrogen oxides are clustered around oil-fired power plants in Saudi Arabia, Kuwait and Lebanon.
However, Dubai, where the number of cars – a major source of nitrogen oxides – increased from 740,000 in 2006 to 1.4 million in 2014, is the most heavily polluted city in the region and the 10th worldwide.
The links between ill health and air pollution are well established, with doctors saying that people living in polluted areas are more likely to develop asthma, upper respiratory tract infections and other conditions.
Studies have also shown that pollution increases the risk of lung cancer and cardiovascular disease, which can cause heart attacks or strokes.
"There's a relationship between air pollution and lung function and health generally," said Dr Bassam Mahboub, a consultant pulmonologist and head of the Emirates Allergy and Respiratory Society.
"We have the issue [in the UAE] of excessive traffic, which correlates directly to the observation of respiratory diseases and impacts quality of life."
The Environment Report 2017 by the Environment Agency Abu Dhabi suggests that air pollution is the biggest environmental factor behind respiratory and cardiovascular diseases in the UAE.
Regional governments are working to improve air quality by transforming transport and power generation. The UAE, for example, has invested heavily in solar-power projects such as the Mohammed Bin Rashid Al Maktoum Solar Park, which is set to become the world's largest solar power array.
Dubai aims to produce three quarters of its energy from clean sources by 2050.
Julien Jreissati, a Middle East and North Africa campaigner at Greenpeace, said that the UAE, Jordan, Egypt and Morocco were "leading the way" regionally in utilising renewable energy. In the Middle East overall, though, development is "slow" compared to the global trend.
“When looking at air quality in cities like Dubai and Cairo, for example, it is clear that bigger and faster renewable deployment should take place,” he said.
This is a view echoed by Habiba Al Marashi, chair of the Emirates Environmental Group.
“Additional measures towards more sustainable sources of energy are required [for the UAE] to be fully able to improve its overall air quality,” she said.
“The country has endeavoured to implement policy and revise its national agenda to make steps towards a healthier and more environmentally sustainable environment.”
Improved public transport systems are a major focus, with the Dubai Metro, which opened in 2009, being followed by a string of other regional projects.
The Doha Metro began operating last month and Riyadh is set to launch a metro system this year that, with six lines running over 176 kilometres, has been described as the world's largest mass transit projects.
The application of air-quality rules varies significantly from country to country. In most nations in this region, vehicle emission standards are much lower than in Europe and efforts to control industrial emissions are limited.Metros have also been proposed for Abu Dhabi, Jeddah and Kuwait City, while Ms Al Marashi said that if there was a metro link between Dubai and Sharjah, 30 per cent of the current traffic problems would be eased and would lead to a reduction in emissions.
But air pollution measures are being taken, ranging from controls on the burning of waste in Oman and limits on the sulphur content of fuel in Bahrain, to efforts in Dubai to make electric cars more financially attractive.
Improved environmental monitoring is also vital, with the Environment Agency Abu Dhabi using more than 20 monitoring stations to assess over a dozen pollutants.
When it comes to achieving clean air, however, the Middle East faces particular difficulties. Figures reported by the WHO show that about 50 per cent of the region's air pollution is from natural sources, mainly dust and sea-salt particles.
“To limit dust storms, we need to decrease the area of arid and semi-arid regions, which are the sources of dust aerosols,” said Dr Diana Francis, an atmospheric scientist at New York University Abu Dhabi.
“The best way to do this is to plant trees because that can reduce areas exposed to dust storms and helps purify the air from other pollutants.”
As it stands, the UAE could be facing a lot more dust storms in the future. Dr Francis said that a study that looked at data from 2000 to 2016 showed that south-eastern parts of the Arabian Peninsula, including the UAE, have seen a 14 per cent increase in the number of dust storms. The same study found that north-eastern and central parts of Arabia have, meanwhile, been seeing fewer dust storms.
"Further research is needed to identify drivers behind the spatio-temporal trends," Dr Francis said.
Another factor in recent years has been political instability, including conflict.
Research published in 2015 using satellite data found that in areas of central Iraq where ISIS was in control, pollution from nitrogen oxides became less severe because people fled the region, resulting in less activity. Syria too, has seen such reductions.
Simultaneously, Lebanon and Jordan, which have taken in large numbers of refugees from elsewhere in the region, have experienced a pollution level increase.