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?
So I will give you the official length. The Great Wall of China is much longer than what has been commonly accepted as fact. The length of the wall was previously thought to be 8850 kilometers or 5500 miles. The actual length, however, is 21,196.18 kilometers. How many miles long is the Great Wall of China? An unbelievable 13,170 miles.