Residents in Beijing enjoyed beautiful blue skies for a few days as China celebrated the 70th anniversary of the end of World War II — and then poof, the smog was back.

A Sept. 3 military parade that marked the end of the war included amazing blue skies in the smog-choked city, but the smog was back the very next day, according to a Want China Times report.

For two weeks between Aug. 20 and Sept. 3, the government had a series of measures to block the air pollution to ensure blue skies for the big parade, knowing that the world would be watching. As a result, the level of PM2.5, or particles that are 2.5 microns or smaller in diameters, reached its lowest point since monitoring began in 2012.

People called the resulting blue skies “parade blue,” and they were gone immediately, prompting some residents to say that it was like a dream that suddenly disappeared. Others said the blue sky made them uneasy because they had grown accustomed to the smog.

It wasn’t easy to reach that point. Officials had to shut down factories throughout northern China. A total of 2,000 local businesses and construction sites were shuttered in Beijing, and the number of cars were restricted. This reduced air pollutants by 30 percent in the surrounding provinces, and a whopping 40 percent within Beijing.

But once the parade ended, moderate pollution reappeared almost immediately. The U.S. embassy measured the Air Quality Index and noted that it dropped from good on Sept. 3 to medium a day later.

Traffic restrictions were lifted, causing pollution-pumping cars to choke the roads again, and factories were back to spewing pollutants back into the atmosphere.