Faulty gas heaters have been blamed for 89 deaths during a cold snap in Iran, according to local media reports.
Iran is experiencing its coldest winter in years
Most of the victims are reported to have died in their sleep after inhaling carbon monoxide gas from badly installed or damaged gas heaters.
Iran is experiencing its coldest winter for years. Snow has blocked roads and airports and schools are closed.
In neighbouring Afghanistan, more than 100 people and 35,000 cattle have died due to the weather in the past week.
Iran's Jomhuri Eslami newspaper and Fars news agency said 89 people had been killed since the start of January by gas heaters.
Carbon monoxide given off by the heaters is odourless and can kill in poorly ventilated spaces.
The Afghan winter has killed people and livestock
Other people have been killed by the freezing temperatures and earlier this month, Tehran declared two days of national holiday, urging people to stay at home to avoid the bitter cold. Temperatures have dropped to -24 degrees Celsius or lower.
In Afghanistan, aid agencies have raised concerns about displaced people and refugees being repatriated from Iran having to survive in extreme conditions.
Iranian and Afghan news agencies report that Iran has responded to Kabul's requests for a temporary halt to forced repatriations during the winter.
Around 9,000 Afghans who were illegally living in Iran have been deported this year.