How Do Air Purifiers Work?
The work of an air purifier is to remove the particulate matter and or gasses from the air. There are several types of air purifiers and many of them work differently. Much of the particulate matter that air purifiers are meant to remove are too small for the human eye to see. Air cleaners use filters, electrical attraction, UV light and ozone to rid the air of these nuisances.
Air Purifiers have been around for more than 150 years. Special needs drove early air cleaner development. Personal protection for firefighters was one of the first developments that lead to today’s modern air purifiers. Protecting ships from German U-boats was another demand sparked air purifier developments. Many technologies we depend on today came from world wide needs in the past. Today allergies and asthma affect more than 50 million Americans. The special needs of modern consumers drive the air purifier market. Consumers want air purifier that remove air particles and gasses.
Air Particles (Particulate Matter) and Gasses
There are two types of indoor air pollutants; particles and gasses. Particulate matter is a complex mixture of extremely small particles and liquid droplets that get into the air. They can be produced by humans or they can occur naturally. Some larger particles like dust and smoke that we can see are examples.
Particulate matter (PM) are put into 2 groups; PM10 and PM2.5 The larger particle size of the two is PM10. PM10 particles can be inhaled. Their size is between 2.5 and 10 microns. PM 10 Particles include mold spores, dust mite droppings, pet dander, pollen and dust. Some PM 10 particle are visible, others are not. PM 2.5 particles are very small. They can only be seen with a microscope. PM 2.5 particles include many things, a few are; smoke, viruses, sulfur dioxide and soot. PM 2.5 particles pose a greater health risk. They can travel deep into human lungs and even get into the blood stream. This can decrease lung function and give you symptoms like coughing.
The second type of pollutants that air purifiers are intended to clean are gasses. Gaseous pollutants are created in numerous ways. Combustion, like cooking, heating and smoking is the most common source. Building material release fumes into the air as they age. Many building materials release fumes from the adhesives and paints used to create them. This release is off-gassing. Off-gassing is a source of gaseous air pollution. Plywood, particle board, paneling, paint and wall paper are just a few of the items in our homes that deliver off-gassing into our environment. These gasses are also known as volatile organic compounds (VOCs). Cleaning products, pesticides, perfumes, scented candles and a host of other household items emit VOCs.
Nature produces gasses. Natural VOCs are some of the most dangerous to your family. Radon is an example of a naturally occurring VOC. Radon is a colorless, odorless, radioactive gas that can be found in indoor air. It comes from uranium in natural sources such as rock, soil, ground water, natural gas, and mineral building materials. So, as uranium breaks down, it releases radon, which attaches to dust particles. Radon may deposit in the lungs and irradiate respiratory tissues. This nasty VOC typically moves through the ground and into a home through cracks and holes in the foundation. Radon may also be present in well water and can be released into the air during showering and other household activities. Some building materials can give off radon. Carbon filters are a great way to deal with these gasses. Natural ventilation, if possible is the best.
To help explain how filters work in an air purifier we can use the analogy of football. Filters trap dirt particle in a number of ways. These methods of trapping dirt particles are called mechanical methods. The first method is impaction. The comparison to football might be this: When a running back tries to go through the line of scrimmage that is clogged with defensive linemen, there is no room for him to get through and score. In the same way when a pollutant tries to go through the tight weave of a filter it is trapped. The second method in interception: Much like a defensive back intercepts the quarterback’s pass, when a dirt particle gets close enough to a filter fiber it is caught and trapped. The third mechanical method is diffusion. Diffusion would compare to a defensive end forcing a play to the outside. The running back runs out of room and is eventually tackled. In a filter, diffusion causes the smaller particle to move out of the main air stream. due to the reduction in speed the small particle matter is trapped by the first two methods.
Residential Air purifiers that use electrical attraction work in one of two ways. particle matter is given an electoral charge, or the filter media is charged. Ionic air purifiers charge particles that move through them. The charged particle is then likely to stick to the walls, ceiling and floor of the room where the ionic air purifier is. Many electronic air purifiers contain filter that have been electrically charge in the manufacturing process. These filters do a decent job of trapping pollutants in the air stream. You have to replace these filters frequently. The best version of electrical attraction occurs in an electrostatic precipitator. An air purifier with an electrostatic precipitator like the LakeAir Maxum uses both technologies. First the air particles are charged in the ion chamber and then are trapped in the collection area where plates have been given a charge. There are 2 big advantages to this type of air cleaner. First this type of air purifier is far more efficient, trapping even more pollution. Second, the filter in the Maxum can be washed. There is no need for expensive replacement filters.
The activated carbon filters in LakeAir residential air purifiers remove many unwanted gaseous pollutants from the air in your home. Activated carbon is a sorbent and it actually absorbs the harmful gasses. Each particle/granule of carbon has a large surface area/pore structure. This allows many contaminants to be absorbed. Activated carbon provides maximum possible exposure in the filter media. There are over 150 different kinds of activated carbon. We take the time to ensure our carbon filters contain the right types for air purification. You must replace a carbon filter after it has absorbed all the odor it can. You cannot wash a carbon filter and reuse it.
UV light air purifiers kill biological organisms. When a living cell passes close enough to a UV light the DNA of the cell is damaged. These cells have to be exposed to UV light for extended periods. The length of time needs varies from cell to cell. How close the cell is to the UV light origin is also a factor. The closer the cell comes to the light bulb the better. UV light is especially effective on viruses and bacteria. The average bacterium is killed in 10 seconds if it is within 6 inches of the UV Bulb. For an air purifier this means the bacteria would probably have to go through the filter several times.
Ozone machines are great for removing odors from the air. They produce large amounts of ozone. An ozone molecule has three atoms of oxygen. Two atoms of oxygen form the basic oxygen molecule. The third oxygen atom can detach from the ozone molecule, and re-attach to molecules of other substances. Ozone can attach itself to odor molecule and in doing so eliminate the odor. While this is great for removing smells, it is not safe. Too much ozone is bad. Ozone occurs naturally and so long as its levels are low poses no threat to people or pets. No one should be is a room when an ozone machine is running.
Room air purifiers
If the usual methods of addressing indoor air pollution are insufficient, a residential air purifier like the LakeAir Maxum and Excel are good choices. Portable room air cleaners like the Maxum can be used to clean the air in a single room or in specific areas. They are not intended to filter the air in the whole house. A residential air purifier is a great part of your IAQ home protection plan.
Some residential air purifiers are installed in the duct work of a home’s central heating, ventilating, and air-conditioning. These are known as whole house air purifiers. The LakeAir LAD and M series residential air purifiers are whole house air purifiers. Each purifier type has its own strengths and weaknesses depending on the needed application. The Canadian Mortgage Corporation performed a study and found that a residential air purifier like the LAD is one of the best values in improving your homes air quality.