Sources of Aerosol Particles in our Atmosphere. There are many sources of aerosol particles in our atmosphere—some are natural sources, such as mineral dust and sea spray. Other sources such as urban smog and vehicle exhaust are caused by human activities.
Figure 4. Sea Spray Aerosols. When waves break in the ocean, aerosol particles are formed. Image credit: Haim Weizman. Another natural source of particulate matter is sea spray from the ocean. Think about walking along the beach—does the crisp ocean breeze feel different from the wind when you are further inland? When you are near the ocean, you are probably feeling the sea spray—small droplets of water and other particles that are suspended in the air. The ocean water contains salt and other organic compounds that are released by the algae, bacteria, and other life forms that live in the ocean.
When waves break, droplets of sea water containing these salts and organic matter are entrained in the atmosphere.
The water in these small droplets can evaporate, which leaves a solid particle made up of the sea salt and organic compounds. Human sources of aerosol particles include smoke from fires, vehicle exhaust, and factories. When hydrocarbon fuels such as the gasoline in our cars are burned, what happens?
On a cold day, you may see smoke coming out of the exhaust pipe in your car, and maybe even some drops of water. When fuel is burned, it undergoes combustion. Combustion is a chemical reaction where the fuel reacts with oxygen O 2 in the air to break down into smaller compounds—the main products are carbon dioxide CO 2 and water H 2 O. However, these fuels can also react through incomplete combustion, which forms carbon monoxide CO instead of carbon dioxide.
In addition to these natural and human sources of aerosol particles, there are also secondary sources of aerosol particles that come from chemical reactions in our atmosphere.
Gases, such as ozone, can react with organic gases in the air to form solid products—which form aerosol particles! Based on these sources of aerosols, can you think of some potential sources of aerosol particles in your community?
Which areas in your community might have high levels of particulate matter? Figure 5. Direct aerosol effect. Figure 6. Light Scattering. A Light scattering causes an incoming light wave yellow arrow to be scattered in all directions green arrows through its interaction with a particle blue circle B Light scattering is based on the fact that light is an electromagnetic wave.
The electromagnetic wave exerts a force on a charged particle, such as an electron, or a polar molecule. When this charged particle moves as a result of the force, a new light wave is emitted.
This is the scattered light. C Particles of different sizes cause the light to be scattered in different directions. Figure 7. Formation of Cloud Droplets. The water vapor in the atmosphere needs a particle, called a cloud condensation nucleus, to condense on.
When a particle is present, water can condense onto it, forming a cloud droplet. Figure 8. Particulate matter penetration into the human respiratory system. Based on their size, particles can penetrate into different parts of the human respiratory system. Smaller particles, however, are more likely to penetrate more deeply into our lungs, into the trachea, bronchioles, or alveoli.
Figure adapted by TH Bertram. The health effects of the particles are directly related to their size. These particles pose the most health risk.
Inhalable coarse particles are particles between 2. As Figure 8 shows, these particles are usually deposited in the nose, pharynx, and larynx. Fine particles have a diameter less than 2. Keeping the pressure constant As the product is used the liquid propellant evaporates to fill the space and keep the pressure at three bar.
When you shake or use an aerosol you can feel it cool rapidly. Can you find some liquids that might be suitable from this table? Questions 1. Which two liquids in the table might be suitable for use as the propellant in aerosols? Is it the gas or liquid in an aerosol that exerts pressure? Apart from being a propellant, which other job must an aerosol liquid do? Where would an aerosol with butane propellant stop working? Compressed air pump spray bottle These bottles are used for spraying weedkiller or insecticide dissolved in water.
The pump compresses the air in the space above the water. Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots.
Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Prev NEXT. Everyday Innovations. The chemical makeup of the propellant and product The ratio of propellant to product The pressure of the propellant The size and shape of the valve system. Caution and Environmental Hazard. Read More. What are aerosols? How cans are made It's O. Cite This! Print Citation.
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