Respirators are not the same as surgical masks. Surgical masks do not protect against breathing in very small particles such as dust or mold because they do not fit tightly to the face, allowing air particles to leak in around the edge of the mask.
6. How long did it take to build the Great Wall in China? The Great Wall of China was built in several stages, not in one continuous effort. Beginning is the 6-7th century BC and ending in the 16th century AD. 7. How wide and how tall the Great Wall of China is? The Great Wall is wide enough at the top for five horses or ten men to walk side by side. The Great Wall ranges in height from just a few feet to over 30 feet tall. Since some of the Wall is built on mountain peaks and high ridges, it looks even taller. 8. What is the best time to visit the Great Wall of China?
published on 22 August 2015. The Great Wall of China is a barrier fortification in northern China running west-to-east 13,171 miles (21,196 km) from the Jiayuguan Pass (in the west) to the Hushan Mountains in Liaoning Province in the east, ending at the Bohai Gulf.