The use of a low-grade fuel by power plants amid a gasoline shortage in Iran is linked to severe harm to public health and even fatalities, a parliamentarian says.

Morteza Khatami, a member of the parliamentary Health Committee, warned the continued use of mazut (a heavy, low-grade fuel oil) has seen a rise in infections, outpatient visits, hospitalizations and deaths attributed to pollutants.

The Iranian authorities have responded to the surge in air pollution by closing schools in Tehran and several other provinces. In the capital, primary and secondary schools have been closed since Monday. Vulnerable groups including children, pregnant women, and individuals with heart or lung conditions have been advised to wear masks in public and to avoid outdoor activities.

Government officials attribute the pollution crisis in Tehran to industrial emissions and the gases from vehicle exhausts and fossil fuel burning. However, the use of mazut is also said to be a significant contributor to air pollution, particularly in industrial settings.

Yet Dariush Golalizadeh, the head of the National Center for Air and Climate Change, claimed that there is no mazut burning in Tehran's power plants and denied it is a factor in the air pollution crisis.

Iran has been facing a notable gasoline shortage since last summer, prompting refineries to bulk out the fuel's volume with other substances. The resultant non-standard gasoline contains harmful additives and has significantly contributed to the air pollution crisis in the country.

A recent report by the news outlet Etemad highlighted that Tehran experienced only two clear days in the last year, during which there has been a notable increase in emergency room visits by residents due to polluted air. Iran currently ranks as the sixth-highest global contributor to greenhouse gas emissions, following China, the United States, India, Japan, and Russia.