A commercial street in downtown Tehran is shown ahead of the Iranian New Year, or Nowruz, which marks the first day of spring and the beginning of the year on the Iranian calendar. (Ebrahim Noroozi/AP)

— Residents taking a staycation in the vast Iranian capital during the Nowruz holiday that began with the onset of spring on March 20 are experiencing a rare break from a particularly harsh urban environment.

Most businesses are closed, as are schools. Tehran’s infamous traffic has disappeared temporarily and along with it the layer of air pollution that usually hovers over this bowl-like metropolis.

The city’s chronic pollution, caused mostly by auto emissions and low-quality gasoline, is some of the worst in the world. According to World Health Organization data, Tehran’s air is more toxic than that of Mexico City or Bangkok and is the cause of more than 4,000 deaths per year in the capital.

Compounding matters are Tehran’s high altitude — nearly 4,000 feet above sea level — a lack of wind during the winter months and drought conditions that have made Tehran’s arid climate even drier. Last month, Tehran’s governor said there had been 147 days of substandard air in the previous year.

But for a few days each year, the 13,000-foot peak of Tochal, the mountain on the northern border of Tehran, is visible from nearly all points in the city. The fresh dusting of snow under a perfectly blue sky reminds longtime residents of an era before the city was flooded by people, and later cars.

“As far back as my great-grandfather, our family has lived in Tehran,” said Gholamali Shamsi, a Persian-rug seller. “Imagine what Tehran would be like if the population never grew. It would be just like it is this week.”

Home to more than 12 million people, Tehran feels empty during the Nowruz break, with many who live here using the 16-day-long holiday, which marks the Iranian new year, to escape the city.

The number of Iranians traveling during the holiday season is difficult to gauge accurately, because many use their own cars to get around. But the minister of transportation, Abbas Akhundi, said last week that 2.1 million Iranians would travel by train during the two weeks of Nowruz and that domestic airlines have more than 15,000 flights scheduled for the same period.

Tour operators say they advise potential foreign visitors to avoid visiting Iran during the holidays; hotels outside the capital are completely booked with domestic tourists. “We ask them to consider coming later in April or May, or we tell them to just come to Tehran. This is by far the best time of year to be here,” travel agent Abbas Hosseini said.

In addition to Iran’s popular tourist sites, including the ancient cities of Isfahan and Shiraz, hundreds of thousands head for the Caspian Sea, a 100-mile drive on narrow roads that has been known to take up to 18 hours this time of year.

Nowruz celebrations and concerts by some of Iran’s most popular exiled musicians are scheduled in countries neighboring Iran, including Turkey, the United Arab Emirates, Georgia and Iraq’s Kurdistan region.

While some authorities have tried to discourage Iranians from spending their vacation — and money — abroad, these package tours continue to grow in popularity.

Nowruz feels like the only time of year when the Islamic state is not organizing some sort of public event.

During the first 24 hours of the new year, Iran’s top leaders delivered televised messages bracing Iranians for another difficult economic year ahead. Since then, however, even politics, or at least what is visible to the public, has gone on hiatus.

To entertain those staying at home, Iran’s state television is broadcasting current and classic Hollywood blockbusters daily. “The Lone Ranger” and “12 Years a Slave” are among films being shown — though some have been altered to local standards.

“I watched ‘Gravity’ the other night and really enjoyed it,” said Yasaman Fatemi, a 31-year-old office worker. “They did such a realistic job of manipulating the film, I had no idea Sandra Bullock’s character wasn’t wearing sleeves and long pants in the original version.”

But her mother was less enthusiastic about how “Titanic” was censored.

“I saw the original version, and it seems like they cut out half of the film,” Anousheh Fatemi said.