What is Ionization?
Ionization refers to how a molecule or atom acquires a positive charge or negative charge by gaining or losing electrons. The electrically charged molecule or atom is referred to as an ion. In nature, this process occurs through a release of energy into the air in the form of lightning and thunderstorms, by molecular friction within wind and rain, and the splitting of water molecules into droplets by waterfalls and ocean surf.
Interest in this topic took on steam following the release of the book The Ion Effect in 1978. Nowadays, many people are eager to learn more about ionizers. The hype around ionizer air purifiers has led many people to research these air purification systems for use in varied environments. Let us now examine this topic in more detail and attempt to answer the following question:
How does an ionizer air purifier work, and can it improve indoor air quality?
What is an Ionizer?
Ionizers have numerous names, including air ionizers, ionizing air purifiers, ionic air purifiers, and ion generators. Ionizing air purifiers use a high voltage to give a negative electric charge to particles or molecules that move through the ionizer or air. The resultant molecules are charged (ions) and tend to stick to airborne particles such as smoke, viruses, mold, pollen, dust, etc., which then fall out of the air and settle onto nearby surfaces. In essence, ionizers are effective in reducing the number of small airborne particles whose electrical polarity attracts the ions.
Ionizers and Electrostatic Air Purifiers
Unlike pure ionizers, electrostatic air purifiers have a charged collector plate that plays a massive role in attracting particles. Without a charged collector plate, the charged particles are attracted to the floor, carpets, and curtains, or somewhere else in a room.
Types of Ionizers
Many commercial ionizers operate on one of two principles:
1. Corona: By concentrating a high-voltage electric field at a point, the dielectric breakdown voltage of the air is exceeded. High voltage is applied to an emitter point, causing a corona effect that ionizes the air.
2. Needle Point: Sends pulsating electrical charges through the air from the point of a small metal needle.
The production of electrical charges varies based on the following approaches:
- AC Ionizers
These types of ionizers use a transformer to multiply the Alternating Current (AC) power line voltage. Therefore, every second, the power cycles from positive to negative many times, and the AC ionizers produce positive and negative ions from their emitters. However, since the cycle of frequency is fast, most of the ions may end up recombining unless blowers and fans are used.
- Pulsed DC Ionizers
These air purifiers use separate power supplies with dedicated emitters to generate negative and positive voltages. These power supplies alternate between positive and negative at a lower frequency compared to the AC ionizers. Therefore, pulsed DC ionizers have reduced particle recombination, enabling the operator to reduce airflow to make the room more comfortable without sacrificing performance.
- Steady State DC Ionizers
Although the steady-state ionizers use separate power supplies & emitters, both supplies are on all the time (the positive and negative do not alternate). Although there is some particle recombination, the ion density is higher because both supplies operate simultaneously.
If you are considering buying an ionizing air purifier, it is essential to understand that they are available in many different design forms, such as:
- Fan-less ionizers that rely on the room’s air current to carry particles away to improve the air quality. Although they are quiet, they take a lot of time to purify the air in a room.
- Ionizers equipped with fans which are generally more efficient but can be noisy.
- Hybrid ionizers which are combined with different air purification technologies. For example, ionizers with activated carbon filters to remove gases such as odors, volatile organic compounds (VOCs), etc., and/or a HEPA filter to remove more airborne particulate0b5c84.
Are Ionizer Air Purifiers Safe and Effective?
This debate seems to linger on in the press. The concerns range from ozone production to other Volatile Organic Compounds (VOCs). It is not uncommon to find studies and reports claiming ionizer air purifiers can actually be the source of VOC production in some environments.
Hence, it is essential to understand that “ionizer” is a broad term, and therefore, details and specifics matter. There is a big difference between ionizers that work on the corona discharge principle versus Needlepoint Bipolar Ionization or NPBI. The latter does not use a dielectric, and so the power needed for them to work is controlled to less than 12.07eV, which mitigates the production of ozone, aldehydes, and other by-products. As a result, this technology is used in many environments, including hospitals, clinics, schools, airports, etc.
Today, ionizers that comply with UL 2998, UL 867, or other regulatory standards can state they meet safety and efficacy requirements. For more information, check out California Certified Air Cleaning Devices.
Practical Use of Ionizer Air Purifiers
Here are a couple of important tips you can follow to maintain the safety and effectiveness of these devices and your environment:
- Clean the area around the ionizer regularly with a vacuum cleaner (preferably with a HEPA filter)
- For electrostatic devices, clean the collector plate regularly
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