Take a deep breath. Now, take a really deep breath. okay, right? Breathing is an area we don't usually pay much attention to, but it is very important for our continued survival. We cannot survive more than a few minutes without breathing, without the oxygen needed to nourish every cell in our body, and without releasing unnecessary waste, mainly carbon dioxide. The volume of each breath at rest is about 500 milliliters (about 0.5 quarts). But did you know that with every breath you breathe, you breathe in many substances other than oxygen? In addition to the harmless form of nitrogen, which makes up more than three-quarters of the Earth's atmosphere, we inhale air pollutants such as ozone, nitric oxide, sulfur dioxide and carbon monoxide. You may have heard of these gaseous pollutants, especially ozone. In high concentrations, it can be harmful to health. But what is surprising to many people is that each breath can contain very small solid or liquid particles. These particles are also considered air pollutants and can cause serious health problems.
Health Effects
Particles of various sizes are found in the atmosphere. Dust particles, which everyone has seen floating in sunlight at least once, are some of the largest, measuring between 100 and 1000 microns (micrometers) in length and one millionth of a meter. Particles thrown into the air during dust storms are slightly smaller, about 10,100 microns. The diameter of pollen grains, which causes great suffering to many people, is about 3200 microns. But wait, we haven't gotten to anything really bad yet! Particles larger than 10 microns, such as dust and pollen, do not stay in the atmosphere long because the endless attraction of gravity pulls them back to the surface in minutes or hours. On the other hand, particles that are less than 2.5 microns in size (or less than 1/30 the width of a human hair) are so small that they can remain in the air for several days, are carried by the wind, and are very small. Air flows. Unlike large particles such as dust and pollen that do not penetrate very far into the body outside the nasal passages when inhaled, these small particles can be inhaled deep into the respiratory tract. Because of their ability to penetrate deep into the bronchi, small particles (called PM2.5 by atmospheric scientists) have been linked to several serious health problems. Exposure to high levels of fine particles is well known to exacerbate respiratory conditions such as asthma and emphysema. An association was also found between high PM2.5 concentrations and the development of lung cancer and congenital malformations. Over the past decade, evidence has been accumulating that small particles can penetrate the deepest parts of the lungs and even enter the bloodstream and affect other organs. In particular, exposure to PM2.5 has been associated with an increased risk of cardiovascular disease and heart attack. Recent studies have shown that ultrafine particles (under 0.1 micrometers) can cross cell membranes and enter other organs in the body, even the brain. Overall, exposure to particulate air pollution is estimated to cause over 20,000 deaths annually in the United States, which would not have occurred without exposure. Fortunately, regulations imposed by the U S Environmental Protection Agency have reduced the average PM2.5 concentration in the United States over the past two decades. However, many places (up to 4 in 10 of all U S residents, according to the American Lung Association) still experience chronically high PM2.5 levels, potentially leading to the premature death of thousands of U S citizens in the area . Airborne particles also impair the visibility of the atmosphere, resulting in foggy conditions commonly associated with air pollution. The more particles in the atmosphere per cubic centimeter, the more the incoming solar radiation is scattered. With a high concentration of particles, the sun's rays do not pass directly through the atmosphere, but are scattered in all directions, reflecting off some object in our field of view and entering the eye. We see fog when the amount of scattered sunlight exceeds the amount that enters the eye directly from the object. ATDD scientists work on the National Science Steering Committee, which oversees the Air Quality Monitoring Network (IMPROVE) to improve and maintain visibility of the American atmosphere. U S National parks and other protected areas. Atmospheric particles also affect Earth's weather and climate. Higher particle concentrations cause incoming sunlight to be scattered back into space, reducing the net heating of the Earth's surface. Also, particles are actually required for cloud formation and precipitation. As the number of particles in the atmosphere changes, this affects the physical properties of clouds, which can change the number of clouds, their spatial extent, and their radiative reflectance, which in turn affects the overall heating (or cooling) of the Earth's surface. The interaction of atmospheric particles with clouds is a complex subject that is an active area of ongoing scientific research.
Sources
So where did all these atmospheric particles come from? Many of these are emitted directly into the atmosphere from a variety of sources, such as gasoline and diesel vehicles, commercial boiler houses, coal-fired power plants, and exhaust gases from industrial and manufacturing processes. Natural causes, such as wildfires and volcanoes, also directly affect the amount of particles in the air. However, a large fraction of all particles in the atmosphere are produced by complex chemical and physical processes that convert gaseous pollutants into solid and liquid forms. These gaseous precursors to particles include nitrogen oxides and sulfur dioxide from exhaust gases from coal and natural gas fueled vehicles and power plants, hydrocarbons from gasoline vaporization during refueling, and fossil fuels.
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