Beggar, Beater, Bedroom: Air Purifier's Impact

Air purifiers are devices that can help improve the air quality in your home. They are particularly useful for people with allergies or respiratory issues, as they can remove common allergens and fine particles from the air. When shopping for an air purifier, it is important to consider the area coverage, filtration system, cost, and speed options. Here is a list of the best air purifiers on the market:

- Best Overall: Coway Airmega True HEPA Purifier - This purifier has a four-stage filtration design, including a pre-filter, deodorization filter, True HEPA filter, and Vital Ion. It can cover spaces up to 874 square feet and has a quiet auto mode that automatically detects and regulates air quality.

- Runner-Up: Coway Airmega 250 Smart Air Purifier - With a four-layer filtration system, this purifier can capture and contain 99.999% of viruses and bacteria. It has smart features, including a phone app that allows you to monitor and control the purifier remotely.

- Most Versatile: Dyson Purifier Humidify+Cool Formaldehyde - This 3-in-1 device purifies the air, humidifies it, and cools it down. It has a HEPA filtration system and a carbon filter to detect and remove formaldehyde. It also has smart capabilities and a night mode for quieter operation.

- Best Budget Pick: Clorox Smart Medium Room Air Purifier - This purifier has a three-stage filtration system, including a True HEPA filter that captures 99.97% of allergens and particulates. It has smart features such as Alexa voice integration and a real-time air quality feedback display.

- Most Customizable: Rabbit Air A3 Ultra Quiet Air Purifier - This purifier has a quiet operation, a washable pre-filter, and a five-year warranty. It has a fully smart functionality with a phone or tablet app that allows for remote control and real-time air quality monitoring.

- Most Environmentally Friendly: Briiv Air Filter - This purifier uses moss as a key ingredient to purify the air. It has a simple touch-activated control zone and an app for more advanced features. It is effective in reducing CO₂ levels and improving air quality.

HEPA filters: These filters are certified to capture 99.97% of particles with a diameter of 0.3 micrometres

HEPA filters are highly regulated and rigorously certified filters that are required to meet strict standards set by the United States Department of Energy (DOE). They are made of materials such as tightly interwoven glass and synthetic fibres that allow only the tiniest particles to pass through.

HEPA filters are designed to remove a minimum of 99.97% of dust, pollen, mould, bacteria, and any particles in the air with a diameter specification of 0.3 microns. Particles that are larger or smaller than 0.3 microns are trapped with even greater efficiency.

The 0.3-micron diameter is the worst-case particle size, also known as the most penetrating particle size (MPPS). Particles that are larger or smaller are trapped with higher efficiency. Using the worst-case particle size results in the worst-case efficiency rating.

The North American definition of "true HEPA" means that a filter removes at least 99.97% of airborne particles of a 0.3-micron diameter in a single pass. For reference, human hair usually measures between 20 and 180 microns across. A particle with a 0.3-micron diameter is the toughest size to remove via physical, HEPA-type filtration. So both larger and—counterintuitively—smaller particles are captured more efficiently.

The European true HEPA equivalent is designated H13, and its requirements are virtually identical: 99.95% single-pass capture of the most penetrating particle size (typically close to 0.3 microns).

There are three main categories of HEPA-certified filters:

• "HEPA-like" filters: These are not genuine HEPA filters and will not provide the same level of filtration. They are not held to the same rigorous testing standards as true HEPA filters.
• True HEPA filters: These filters are tested and certified to meet stringent HEPA standards, meaning they are proven to remove 99.97% of particles as small as 0.3 microns.
• H13-H14 Medical-Grade HEPA filters: H13 filters are a specialised type of true HEPA filter, often used in hospital settings. While true HEPA filters target particles down to 0.3 microns, H13 filters are rated to capture particles as small as 0.1 microns.

True HEPA filters are ideal for settings where air purity is critical, such as hospitals, cleanrooms, and homes with individuals suffering from severe allergies or respiratory conditions.

Activated carbon filters: These filters capture certain types of gases, including some odour-causing molecules

Activated carbon filters are highly effective at removing gases and odours from the air. They are created by heating carbon-rich materials, such as wood, coal or coconut shells, to form a highly porous material with a large surface area. This activated carbon is then treated with chemicals to enhance its ability to capture certain gases.

Activated carbon filters are particularly good at removing volatile organic compounds (VOCs), which are gaseous substances that are released from common household products. They are also effective at removing odours, such as tobacco smoke, and gases produced by combustion, including nitrogen and sulphur oxides.

However, activated carbon filters are not as effective at capturing particles, such as dust, pollen or mould, and they need to be replaced more frequently than mechanical filters. They also do not work well against formaldehyde, ammonia or nitrogen oxide.

Ozone generators: These machines produce ozone, which can react with certain pollutants to alter their chemical composition. However, ozone has been linked to decreased lung function and increased risks of coughing, chest pain, and lung tissue inflammation

Ozone generators produce ozone, a highly reactive gas composed of three oxygen atoms. While ozone in the upper atmosphere protects us from harmful ultraviolet (UV) light, ground-level ozone is a major component of smog and is harmful to health.

Ozone generators are often marketed as "air purifiers" or "air cleaners", with manufacturers claiming that ozone can purify the air and remove airborne particles, chemicals, mould, viruses, bacteria, and odours. However, ozone is only partially effective at cleaning the air and can be dangerous to human health.

• Eye, nose, and throat irritation
• Shortness of breath
• Chest pain and coughing
• Worsening of asthma symptoms
• Increased risk of respiratory infection
• Lung tissue inflammation
• Permanent lung damage from repeated exposure or elevated exposure

Ozone generators are particularly dangerous for children, the elderly, and those who suffer from asthma or other respiratory diseases.

Ozone generators should not be used indoors, especially in spaces occupied by people or animals. To improve indoor air quality, it is recommended to reduce or eliminate indoor pollution sources, increase ventilation, and use stand-alone portable filtration units with charcoal and/or zeolite filters.

Electrostatic precipitators and ionizers: These electronic models charge particles in the air so that they stick to nearby surfaces or plates on the machine

Electrostatic precipitators and ionizers are electronic air purifiers that use electrostatic force to charge particles in the air, causing them to stick to nearby surfaces or plates on the machine. Here's a detailed overview of how they work and some important considerations:

How Electrostatic Precipitators Work

Electrostatic precipitators use electrostatic force to attract and capture dust and other particles. They consist of wires and collection plates, with a high voltage applied between the wires and plates to create an electrostatic field. This field ionizes and electrically charges the air. When airborne particles such as dust or pollen pass between the plates, they become charged and are then attracted to and stick to the oppositely charged collection plates. The clean air flows through, leaving the particles trapped on the plates.

Two-Stage Design

Electrostatic precipitators typically have a two-stage design, with a charging section and a collection section. The charging section uses ionizer wires to impart a positive charge to incoming particles. The charged particles are then drawn into a secondary electric field where they are collected on a series of metal plates. This two-stage design helps to reduce ozone production, which is harmful when inhaled.

Efficiency and Energy Use

Electrostatic precipitators are known for their high efficiency in removing small particles from the air. By focusing on these smaller suspended particles, they use less electricity than many other types of air cleaners. This allows them to achieve better air cleaning while consuming less power.

Maintenance and Cleaning

One important consideration with electrostatic precipitators is the need for regular maintenance and cleaning. The collection plates need to be cleaned manually by shaking, scraping, or washing off the collected particles. This process can be challenging and messy, and there is a risk of dislodging dust and particles during cleaning.

Ozone Production

One significant concern with electrostatic precipitators is their potential to produce ozone and nitrogen oxides, which can be harmful to human health. While the amount of ozone generated may be lower than dedicated ozone generators, it still introduces pollution into the room.

Comparison with Ionizers

It's easy to confuse electrostatic precipitators with ionizers, as they both charge particles in the air. However, electrostatic precipitators actively draw in air, charge it, remove contaminants, and release clean air. On the other hand, ionizers simply release charges into the surrounding room, causing particles to stick to nearby surfaces but remaining in the living space.

In summary, electrostatic precipitators and ionizers are electronic air purification methods that use electrostatic forces to charge particles, causing them to stick to surfaces or collection plates. While effective for industrial applications, electrostatic precipitators have some drawbacks for residential use, including ozone production and maintenance challenges.

Ultraviolet germicidal irradiation (UVGI): Some air purifiers use UV lamps to kill airborne viruses, bacteria, and fungal spores. However, UVGI technology may not be effective against all bacteria and mould spores, and it requires prolonged exposure to be effective

Ultraviolet germicidal irradiation (UVGI) is a technology used in some air purifiers to kill airborne viruses, bacteria, and fungal spores. UVGI uses ultraviolet light to kill microorganisms, including bacteria, fungi, viruses, and mould. UVGI air purifiers work by destroying the DNA of microorganisms, breaking down the molecular bonds in their DNA, and destroying nucleic acids, the building blocks of DNA.

While UVGI technology has been used in medical facilities and is advocated by clean-air advocates, it may not be effective against all types of bacteria and mould spores. The Environmental Protection Agency (EPA) states that effective killing of airborne microorganisms such as bacteria and fungi requires higher UV exposure than is typically found in residential units. Prolonged exposure to UV light is necessary for UVGI to be effective, and the placement of UV lamps is critical for successful sterilization.

To ensure sufficient UV exposure, it is recommended to purchase a system with 24,000 or more microwatts. Additionally, stand-alone room purification units may not be as effective as those placed in ventilation ducts, as they only clean the air that passes through them. It is also important to note that UVGI does not remove particles such as pet dander, pollen, and chemicals from the air. Therefore, for the most effective air purification, UVGI should be used in conjunction with a traditional air filtration system.

Frequently asked questions