Health Effects and Toxicology of Particles

Particles also have direct health effects when inhaled. This is especially true of very small particles that can be carried into the innermost parts (alveoli) of lungs. The particles that are most damaging are very small ones less than 2.5 pm in size (less than 1/30 the diameter of a human hair) designated PM2 5 These are mostly condensation aerosols and may contain toxic elements, such as arsenic, acids, such as H2SO4, and carcinogenic polycyclic aromatic hydrocarbons including benzo(a)-pyrene. Because of their very small size, these particles have very high surface-to-volume ratios and biochemically active surfaces. 

Inhalation of asbestos may causes asbestosis (a pneumonia condition), mesothelioma (a tumor of the mesothelial tissue lining the chest cavity around the lungs), and bronchogenic carcinoma 

A significant health concern with particles, especially those from combustion sources, is their ability to carry toxic metals. Of these, lead is of the greatest concern because it usually comes closest to being at a toxic level. Problems with particulate lead in the atmosphere have been greatly reduced by the elimination of tetraethyl lead as a gasoline additive, an application that used to spew tons of lead into the atmosphere every day. Another heavy metal that causes considerable concern is mercury, which can enter the atmosphere bound to particles or as vapor-phase atomic mercury. Airborne mercury from coal combustion can become a serious water pollution problem, leading to unhealthy accumulations of this toxic element in some fish. Other metals that can cause health problems in particulate matter are beryllium, cadmium, chromium, vanadium, nickel, and arsenic (a metalloid). 

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