Depending on their make-up, gases and vapours may be absorbed in the blood. A worker spraying paint without adequate protection may be heavily exposed to organic vapours by breathing. The smaller the size of the particles we breathe, the more deeply they are likely to penetrate into the respiratory system. Some particles are attacked by the body's defence cells, called macrophages , and may be either destroyed or converted into more harmful substances. The more the amount of chemicals we breathe and the longer we are exposed to them, the more serious are the health effects likely to be.
Some individuals are more prone to the effects of chemicals than others.
Similarly, children, the elderly, pregnant women and those weakened by illness are more at risk from the unhealthy effects of chemicals. Where we breathe them Chemicals enter and leave our bodies all the time. Tiny spores, pollen and bacteria by the thousands enter the lungs with each breath. Most of these are breathed out, others are removed or destroyed by the defence mechanisms of our body. Our sense of smell is not always infallible.