The lungs are protected by a series of defense mechanisms in different regions of the respiratory tract. When a person breathes in, particles suspended in the air enter the nose, but not all of them reach the lungs. The nose is an efficient filter. Most large particles are stopped in it, until they are removed mechanically by blowing the nose or sneezing. Some of the smaller particles succeed in passing through the nose to reach the windpipe and the dividing air tubes that lead to the lungs [more information about how particles entering the lungs].
These tubes are called bronchi and bronchioles. All of these airways are lined by cells. The mucus they produce catches most of the dust particles. Tiny hairs called cilia, covering the walls of the air tubes, move the mucus upward and out into the throat, where it is either coughed up and spat out, or swallowed. The air reaches the tiny air sacs (alveoli) in the inner part of the lungs with any dust particles that avoided the defenses in the nose and airways. The air sacs are very important because through them, the body receives oxygen and releases carbon dioxide. Dust that reaches the sacs and the lower part of the airways where there are no cilia is attacked by special cells called macrophages. These are extremely important for the defense of the lungs. They keep the air sacs clean. Macrophages virtually swallow the particles. Then the macrophages, in a way which is not well understood, reach the part of the airways that is covered by cilia. The wavelike motions of the cilia move the macrophages which contain dust to the throat, where they are spat out or swallowed.
Besides macrophages, the lungs have another system for the removal of dust. The lungs can react to the presence of germ-bearing particles by producing certain proteins. These proteins attach to particles to neutralize them. Dusts are tiny solid particles scattered or suspended in the air. The particles are “inorganic” or “organic,” depending on the source of the dust. Inorganic dusts can come from grinding metals or minerals such as rock or soil. Examples of inorganic dusts are silica, asbestos, and coal.
Organic dusts originate from plants or animals. An example of organic dust is dust that arises from handling grain. These dusts can contain a great number of substances. Aside from the vegetable or animal component, organic dusts may also contain fungi or microbes and the toxic substances given off by microbes. For example, histoplasmosis, psittacosis and Q Fever are diseases that people can get if they breathe in organic that are infected with a certain microorganisms. Dusts can also come from organic chemicals (e.g., dyes, pesticides). However, in this OSH Answers document, we are only considering dust particles that cause fibrosis or allergic reactions in the lungs. We are not including chemical dusts that cause cancer or acute toxic effects, for example.
The smoke released by any type of fire (forest, brush, crop, structure, tires, waste or wood burning) is a mixture of particles and chemicals produced by incomplete burning of carbon-containing materials. All smoke contains carbon monoxide, carbon dioxide and particulate matter (PM or soot). Smoke can contain many different chemicals, including aldehydes, acid gases, sulfur dioxide, nitrogen oxides, polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, styrene, metals and dioxins. The type and amount of particles and chemicals in smoke varies depending on what is burning, how much oxygen is available, and the burn temperature.
Exposure to high levels of smoke should be avoided. Individuals are advised to limit their physical exertion if exposure to high levels of smoke cannot be avoided. Individuals with cardiovascular or respiratory conditions (e.g., asthma), fetuses, infants, young children, and the elderly may be more vulnerable to the health effects of smoke exposure.
Inhaling smoke for a short time can cause immediate (acute) effects. Smoke is irritating to the eyes, nose, and throat, and its odor may be nauseating. Studies have shown that some people exposed to heavy smoke have temporary changes in lung function, which makes breathing more difficult. Two of the major agents in smoke that can cause health effects are carbon monoxide gas and very small particles (fine particles, or PM2.5 ). These particles are two and one half (2.5) microns or less in size (25,400 microns equal an inch) and individual particles are too small to be seen with the naked eye.
Inhaling carbon monoxide decreases the body’s oxygen supply. This can cause headaches, reduce alertness, and aggravate a heart condition known as angina. Fine particles are able to travel deeply into the respiratory tract, reaching the lungs. Inhaling fine particles can cause a variety of health effects, including respiratory irritation and shortness of breath, and can worsen medical conditions such as asthma and heart disease. During increased physical exertion, cardiovascular effects can be worsened by exposure to carbon monoxide and particulate matter. Once exposure stops, symptoms from inhaling carbon monoxide or fine particles generally diminish, but may last for a couple of days.
Avoiding smoky situations is the best way to avoid exposure. If your age or health status places you at greater risk from smoke exposure you should speak with your doctor about alternative steps you can take when encountering smoky situations. Anyone with persisting or frequent symptoms that they think are associated with smoke exposure should see their health care provider. Additional information on carbon monoxide and fine particles can be found at the web addresses listed at the end of this fact sheet.
There is also the potential for chronic health effects from exposure to the components of smoke. Long term exposure to ambient air containing fine particles has been associated with increases in cardiovascular disease and mortality in populations living in areas with higher fine particulate air pollution. Frequent exposure to smoke for brief periods may also cause long-term health effects. Firefighters, who are exposed frequently to smoke, have been examined for long-term health effects (for example, cancer, lung disease, and cardiovascular disease) of repeated smoke exposures. The findings from these studies are not consistent or conclusive. Some studies show an increased frequency of these diseases among firefighters compared to similar male reference populations (e.g., male policemen, white males in the general population), while others do not.
Part 6 of our 9 Part Series on Asthma Triggers takes a look at the adverse health affects caused by Nitrogen Dioxide.
Radon is a gas that has no color, odor, or taste and comes from the natural radioactive breakdown of uranium in the ground. You can be exposed to radon by two main sources:
- Radon in the air in your home (frequently called “radon in indoor air”)
- Radon in drinking water.
Radon can get into the air your breathe and into the water you drink. Radon is also found in small amounts in outdoor air. Most of the radon in indoor air comes from soil underneath the home. As uranium breaks down, radon gas forms and seeps into the house. Radon from soil can get into any type of building – homes, offices, and schools – and build up to high levels in the air inside the building. Its gas can also dissolve and accumulate in water from underground sources such as wells. When water that contains radon is used in the home for showering, washing dishes, and cooking, the gas escapes from the water and goes into the air. It is similar to carbonated soda drinks where carbon dioxide is dissolved in the soda and is released when you open the bottle. Some radon also stays in the water, and is not a concern in water that comes from lakes, rivers, and reservoirs because the radon is released into the air before it ever arrives at your tap.
Breathing radon in indoor air can cause lung cancer. The gas decays into radioactive particles that can get trapped in your lungs when you breathe it. As they break down further, these particles release small bursts of energy. This can damage lung tissue and increase your chances of developing lung cancer over the course of your lifetime. People who smoke have an even greater risk. Not everyone exposed to high levels of radon will develop lung cancer. However, radon in indoor air is the second leading cause of lung cancer. About 20,000 deaths a year in the U.S. are caused by breathing radon in indoor air.
Only about 1-2 percent of radon in the air comes from drinking water. However breathing it increases the risk of lung cancer over the course of your lifetime. Some radon stays in the water; drinking water containing radon also presents a risk of developing internal organ cancers, primarily stomach cancer, however this risk is smaller than the risk of developing lung cancer from radon released to air from tap water.
Based on a National Academy of Science report, EPA estimates that radon in drinking water causes about 168 cancer deaths per year: 89% from lung cancer caused by breathing radon released to the indoor air from water and 11% from stomach cancer caused by consuming water containing radon. If Radon is a concern for you, having it tested by a certified firm and determine whether or not you in fact have an issue.
Our 9 Part Series on Asthma Triggers received so much feedback that we made them into Videos. Click the link below to our YouTube Page to view the video as we’ll be loading all 9, one each day.