Air pollution in Yemen is caused by a variety of factors , including emissions from vehicles , power plants and the widespread use of heavy construction tools such as industrial saws. The main source of air pollution , however, particularly in cities such as Sana'a , is emissions from cars and other vehicles. In Sana'a there are more than 300,000 vehicles , many of which are very old having being brought into the country by returning Yemenis after the Gulf war in 1990. After the 1990 Gulf War, thousands of Yemenis returned to their homes and brought their cars with them. A lot of the cars were very old and polluted the environment. The majority of these vehicles use leaded gasoline or local diesel, which contains a high level  of impurities. 

Infact , Yemen remains one of the few countries worldwide that continues to use leaded gasoline in it's cars and other vehicles. There are very few lead-free petrol stations. 

The pollutant concentrations are  estimated to be several times higher than the set standards for air quality.

Air pollution is unpleasant and unhealthy. Breathing highly polluted air from exhaust fumes on daily basis can cause severe respiratory and renal problems. Air pollution represents a financial and environmental burden on Yemeni government. In 2008 , Yemen's Ministry of Environment and Water acknowledged the severity of the problem and started working on national strategy to reduce air pollution. The authorities have since then implemented a few simple measures to improve the air quality e.g. vehicles which were manufactured before year 2000 are no longer permitted entry into the country. The authorities have also reduced the tax on new cars to encourage more people to invest in newly built , modern and more environmentally friendly vehicles.

Another  source of air pollution in Yemen , particularly around it's coastal areas, is the oil industry. Although oil accounts for a large part of Yemen's revenue and is an invaluable economic resource, it's production , exploration and transportation have contributed significantly to air pollution in coastal and marine areas.

Urbanisation , desalination plants , mining , quarrying are all responsible for worsening air pollution in Yemen.

The Ministry of Water and Environment (MWE) is working to reduce air pollution caused by vehicle emissions and thus save on associated health costs amounting to an estimated US$100 million a year in Sanaa alone. 

Pollution in Yemen

Purity and Cleanliness in Yemen

The worst is the ongoing " Yemeni Civil War "that began in March 2015 between two factions claiming to constitute the Yemeni government, along with their supporters and allies. As air raids continue to batter  Yemen, it is heavily polluting it's air and leaving deep environmental scars.

Sources :Numbeo , Yemen today