Is it dry?

If the water content of the air is lower than 20%-30%, it is dry weather, which usually appears in winter. At this time, people generally feel more static electricity, tight nostrils, dry lips and moist air within 60%. At this time, the air is the most comfortable, and more than 60% is humid. Some people with poor breathing or poor joints will feel breathless, weak waist and knees, etc. If they suddenly meet.