Hundreds of people in Israel were treated for respiratory problems and other weather-related ailments Tuesday as a sandstorm engulfed the region, with the cloud of dust massive enough to be seen from space.

Jerusalem recorded its worst air pollution levels ever, at 173 times normal levels. In some other parts of the country, air pollution levels were at their worst for 75 years.

Israel’s emergency medical service Magen David Adom reported that 340 Israelis received medical treatment as a result of the weather, including those suffering from asthma, respiratory problems, shortness of breath and heart issues.

“The MDA will continue to be on alert in light of the heatwave and dust storm,” MDA Director General Eli Bin said.

He urged Israelis to stay indoors, warning that the storm poses a real danger to people’s health, and asked that schools keep children indoors.

The dust has been making its way to Israel from Iraq and Syria over the past week.

Some 800 kilometers above the earth’s surface, NASA satellite images show Israel, Egypt’s Sinai Peninsula, Jordan, Lebanon and parts of Syria covered in the thick brownish-yellow fog. According to the satellite data, the dust cloud rose 600 meters in the air.

In Israel, the concentration of sand particles was highest in the hills, including the Jerusalem area, the southern West Bank and the Golan Heights. In Jerusalem, pollution levels were 173 times higher than the average; in the Negev, 51 times higher; and in the Galilee, 32 times higher.

Meteorologists said the sandstorm would persist at least until Wednesday and be accompanied by a heatwave that would last until the weekend.

The dust storm also hit Lebanon’s coastal capital of Beirut on Tuesday, leaving two people dead, and people have been advised to stay indoors.

The Lebanese state news agency said at least 750 people fainted or suffered breathing problems because of the fine dust.

People have been warned against burning the trash that has piled up on Beirut streets this summer, sparking a political crisis and protests.

In Syria, the storm reached the capital, Damascus. The pro-government Syrian Al-Watan newspaper said the sand had forced the government to halt its airstrikes against rebel fighters north of the central province of Hama.

AFP contributed to this report.