Breath is the second food. It can impact us both positively and negatively.
Nature gave us a sophisticated system for managing the impurities which we inhale along with air. The air we breathe is composed of 78% nitrogen and 21% oxygen. The remaining 1% of air naturally consists of water vapor, carbon dioxide, methane, helium, hydrogen, argon, krypton, neon and xenon. It can also include industrial pollutants from, for example, car exhaust.
It will also include particles (also called aerosols) of dust, smoke, spores, pollen and microbial organisms (called bioaerosols—including bacteria viruses). The respiratory system blocks the unwanted particles fairly effectively via mucus and cilia. Mucus is found throughout most of the breathing system (from the nostrils and nasal cavities to the bronchioles). The mucus attracts and traps particles and the cilia push them gradually upwards until they arrive at the throat where they can be dropped down the esophagus to be consumed or spat out. Sneezing is the mechanism for cleaning the nasal passages.
Nevertheless, some particles reach the alveoli where the intended exchange of gases takes place—oxygen and nitric oxide in and carbon-dioxide out. Here, particles are dealt with by “alveolar macrophages” that can ingest harmful foreign substances, and neutrophils—white blood cells that fight infection.
The positive side of the equation is limited in the sense that we can only breathe