Air Purifiers: Do They Actually Work?

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Chapters

0:00 Introduction
0:59 How do air purifiers work?
1:43 Effectiveness of air purifiers
2:40 Best practices when using purifiers

An air purifier or air cleaner is a device which removes contaminants from the air in a room to improve indoor air quality. These devices are commonly marketed as being beneficial to allergy sufferers and asthmatics, and at reducing or eliminating second-hand tobacco smoke.

The commercially graded air purifiers are manufactured as either small stand-alone units or larger units that can be affixed to an air handler unit (AHU) or to an HVAC unit found in the medical, industrial, and commercial industries. Air purifiers may also be used in industry to remove impurities from air before processing. Pressure swing adsorbers or other adsorption techniques are typically used for this. In 1830, a patent was awarded to Charles Anthony Deane for a device comprising a copper helmet with an attached flexible collar and garment. A long leather hose attached to the rear of the helmet was to be used to supply air, the original concept being that it would be pumped using a double bellows. A short pipe allowed breathed air to escape. The garment was to be constructed from leather or airtight cloth, secured by straps.[1] In the 1860s, John Stenhouse filed two patents applying the absorbent properties of wood charcoal to air purification (patents 19 July 1860 and 21 May 1867), thereby creating the first practical respirator.[2]

In 1871, the physicist John Tyndall wrote about his invention, a fireman's respirator, as a result of a combination of protective features of the Stenhouse's respirator and other breathing devices.[3] This invention was later described in 1875.[4]

In the 1950s, HEPA filters were commercialized as highly efficient air filters, after being put to use in the 1940s in the United States' Manhattan Project to control airborne radioactive contaminants.[5][6]

The first residential HEPA filter was reportedly sold in 1963 by brothers Manfred and Klaus Hammes in Germany,[7] who created the Incen Air Corporation which was the precursor to the IQAir corporation.[citation needed]
Use and benefits

Dust, pollen, pet dander, mold spores,[8] and dust mite feces can act as allergens, triggering allergies in sensitive people. Smoke particles and volatile organic compounds (VOCs) can pose a risk to health. Exposure to various components such as VOCs increases the likelihood of experiencing symptoms of sick building syndrome.[9]
COVID-19
See also: Impact of the COVID-19 pandemic on public transport § Research and development
A Sharp FU-888SV Plasmacluster air purifier.
The same air purifier, cover removed.

Joseph Allen, director of the Healthy Buildings program at Harvard's School of Public Health, recommends that school classrooms use an air purifier with a HEPA filter as a way to reduce transmission of COVID-19 virus, saying "Portables with a high-efficiency HEPA filter and sized for the appropriate room can capture 99.97 percent of airborne particles."[10]

One fluid dynamic modelling study from January 2021 suggests that operating air purifiers or air ventilation systems in confined spaces, such as an elevator, during their occupancy by multiple people leads to air circulation effects that could, theoretically, enhance viral transmission.[11] However, real-life testing of portable HEPA/UV air filters in COVID-19 wards in hospital demonstrated complete elimination of air-borne SARS-CoV-2.[12] Interestingly this report also showed a significant reduction in other bacteria, fungal and viral bioaerosol, suggesting that portable filters such as this may be able to prevent not only nosocomial spread of COVID-19 but also other hospital-acquired infections.
Purifying techniques
An air purifier placed under a table

There are two types of air purifying technologies, active and passive. Active air purifiers release negatively charged ions into the air, causing pollutants to stick to surfaces, while passive air purification units use air filters to remove pollutants. Passive purifiers are more efficient since all the dust and particulate matter is permanently removed from the air and collected in the filters.[13] Several different processes of varying effectiveness can be used to purify air. As of 2005, the most common methods were high-efficiency particulate air (HEPA) filters and ultraviolet germicidal irradiation (UVGI).[14]
Filtration

Air filter purification traps airborne particles by size exclusion. Air is forced through a filter and particles are physically captured by the filter. Various filters exist notably including:

[UnrelatedNonsense]

I’m thoroughly convinced they work as long as you get a good one. I have a few Hathaspace 2.0 in my house and my seasonal allergies have gone down tremendously.

[Clevast]

Every household should really invest for an air purifier.

[tolisl]

I am writing to you just to talk about the filters order and their lifespan. My background is chemical engineering just to mention. The most correct way to place filters is mesh, hepa and then carbon. Why's that? Activated carbon's surface area will more drastically decrease with dust than the hepa and gases will not stick. So proper way is to filter all particles and then pass the gases through the carbon. I don't know if this is counter intuitive. Another more interesting issue is the prefilter. Fine mesh vs more coarse like levoit's. Fine mesh filters are used to protect equipment like the fine mesh filters found in dryers. Also both have the same performance if equipment protection is not vital. Why? Because the mesh doesn't do the actual filtration! The mesh is there to build dust layers and these exact layers are the filter which makes it efficient. That's filtration 101 btw. So another thing is mesh filter cleaning. HEPA will clog faster if the mesh filter is regularly cleaned since it will not filter as efficiently.

[switchunboxing]

I have SO MUCH dust in the air in my apartment I've never seen anything like it. And yes they regularly replace the AC filter every 3 months. I use an air purifier every night just for the white noise alone, but I'm not sure it's helped with dust. I'm starting to take it into my living room during the day where the problem is, just to to try and address this. But I've had bad allergies for the past 3 weeks now. I wonder if its the dust or something.

[glazzinfo]

How can we use ventilation if we are living in the most air polluted city in the world

[Bushehri]

Ty I was wondering 🤔 💭 is it working or not the air purifier

[dafenshe]

😢I live in the African desert. In recent years, with the increase in factories and population density, the condition of the local community has deteriorated. Respiratory diseases and allergies of all kinds have spread, and in the absence of a culture of afforestation, cleanliness, or nature centers, this region has been destroyed. Here are people who do not know anything about dust or viruses. They just live in ignorance and die. They get sick and do not know the cause of the curse.🤦🏼‍♂️
Desert dust may contain a variety of harmful substances and chemical pollutants, and these components can vary depending on the geographic region and surrounding environmental effects. However, there are some common components that may be present in desert dust, including:😢

1. Heavy metals: Desert dust may contain heavy metals such as lead, mercury, cadmium, nickel, chromium, and aluminum. These metals can be toxic and pose a risk to public health when inhaled or ingested through dust.😢

2. Organic pollutants: Desert dust can contain organic pollutants such as volatile organic compounds (VOCs), which are emitted from various sources like industries, vehicles, and agricultural crops.😢

3. Bacteria and fungi: Desert dust may carry airborne bacteria and fungi, which can be pathogenic when inhaled.😢

4. Attached organic pollutants: Organic pollutants such as pesticides and persistent organic pollutants can be absorbed onto desert dust particles, increasing individuals' exposure to these harmful chemicals.

Remember that desert dust may also carry biological materials such as plant pollens, grains, and other organic substances that can cause allergies in susceptible individuals.

To reduce exposure to harmful substances in desert dust, it is advised to follow health safety guidelines such as using protective masks, cleaning exposed surfaces, ventilating enclosed spaces, and other appropriate preventive measures.😢

[Omar-lfiq]

I was suffering so bad with runny nose every day. I started using one and my suffering stop. By the way we have a dog.

[chadsummers]

do you have an air purifier expensive vs cheap? i just want to know the difference before buying one, thanks

[Adeline]

The air purifier in ny bedroom was flashing red meaning it needs a new filter. I unplugged it and went to sleep without it.
Man when i woke up the next morning for work i actually felt sick. I thought maybe allergies. Felt bad most of the day.
That night i moved my living room air purifier into my bedroom. This morning when I woke up I felt great.
Yes air ourifiers definitely work and ill bever be without one.

[lannyplans]

Change the water filter like in the video to purify air? And Hepa filters capture the smaller particles, not the carbon filters.

[fonziebulldog]

Have used different air purifiers for the last 20 years and they do get better and better. Have you once had a fully working one at home you most probebly know the difference in how the air was before and after the use on a air purifier. Some use to neglect clean air at home for some strange reason or they dont believe in these systems. Both have sadly wrong when its most probably one of the better technologies you could get these days with one single purpose ... To let you have clean air at home and thats for sure not a bad thing.

[Monik_Singh_Realtor]

Does it help inside the basement where the air has moisture?

[nickyyy]

I just bought a winix air purifier from costco and Im not noticing ang difference in the dust in my house. I followed the instructions exactly the way they were describing (it was literally just inserting the filter) but the only thing it seems to be doing is blowing air from the top which just spreads the dust around if anything. Is this normal??

[zjsxvbu]

They're very useful for me as pet dander makes me itchy as well as clearing out dust which makes me sneeze

[AnmolSingh-hwqk]

How do I use it if my room already has ventilation problems if I don't open the windows?

[jamesm]

Why is so many people against purifiers with ultraviolet light?

[sanamlive]

Use air purifier and then clean the filter without wearing mask😂

[MAGAMAN]

"vacuum around your air purifier so it doesn't suck up the pet hair" Wait, what? Isn't that what a lot of people buy an air purifier for?

[rabiamariamsamra]

Neeno neeno thank you waseem air ya tuti frutti