Describe the Mechanism of Breathing
The process of breathing consists of 2 phases:
In this process diaphragm contracts. The inter coastal muscles contacts raising the rib cage, which in turn expands the lungs. As a result air pressure within the lungs decreases and air from outside is pulled into the lungs.
In this process inter coastal muscles relax. The diaphragm relaxes and assumes the shape of dome. The volume of lungs decreases which result in an increase in the air pressure in lungs. Thus air is forced out of the lungs.
And in any case, books should be regularly cleaned or vacuumed, and the cabinets should be ventilated. Then you will reduce the risk of allergic disorders. And through books, you can become infected with some infectious diseases: if sputum particles of a sick person get on the pages, the pathogens feel good there some time. The chance of inhaling dust with the pathogen is not so great, but it is (although with much greater chances you can get infected in any public place).