Beijing’s first-ever red alert for air pollution was historic for not just shutting down schools and factories in the capital, but for also allowing Chinese soldiers guarding Tiananmen Square to wear air filter masks for the first time as they perform their duties.

As seen in these pictures on December 9, Chinese PLA soldiers stationed at Tian’anmen Square can be seen wearing a type of black cloth mask over their faces. And while people were warned to stay inside during the red alert, it didn’t keep tourists from attending the daily flag raising ceremony that the soldiers perform every day.