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Discover why not all residential air cleaners are safe here.

Originally published
Originally published: 2/1/2020

Be sure to research what you sell to protect yourself from future product liability issues.


The HVACR market has been inundated with dozens of air cleaning technologies and equipment over the last decade. Contractors have discovered this growing niche to be a lucrative market for promoting indoor air quality to consumers.

The emergence of many research reports on the dangers of ozone, a gas that is a byproduct of some cleaning methods, however, should prompt contractors to research what methodologies are the safest or they could be opening themselves up to future product liabilities issues.

Arm yourself with knowledge on how air cleaners work and determine whether they produce harmful byproducts, such as ozone, to not only provide your customers the safest possible IAQ, but to protect your business from possible liability issues.

Ozone Dangers

Ultraviolet germicidal irradiation (UVGI) technology isn’t new and has been used to disinfect air for decades and water for more than a century.

There’s no doubt UV lamp systems effectively disinfect biological contaminants especially those that pass two UVGI effectiveness test standards: ANSI/ASHRAE Standard 185.1 for UVGI lamps in in-duct airstream irradiation; and ANCI/ASHRAE Standard 185.2 for UVGI lamps for in-duct surface irradiation. Besides ductwork and plenum air supply disinfection, UV lamps also prevent mold and other biological growth on evaporator coils and air handler interiors.

Unfortunately, some UV technology for HVACR systems generate ozone, which multiple studies within the last several years have proven harmful to human respiratory systems. While ozone is sometimes an unintended byproduct, some UV lamp systems may also intentionally produce ozone by design.

For example, some manufacturers purposefully use specific UV wavelengths that create ozone to produce the distinct, clean-smelling ozone odor.

Whether or not a UV lamp generates ozone is dependent upon its wavelength. UV is produced in various forms: UV-A used for blacklights (320 to 400 nanometers (nm)); UV-B used in tanning beds (280 to 320-nm); and the most lethal germicidal wavelength, UV-C (254-nm) is ideal for disinfection. UV-C deactivates microorganism reproduction by altering their DNA structure.

While UV-C is the most lethal for microorganisms, UV lamps using the UV-V wavelength at 185nm produce ozone. UVC lamps at or above 254-nm do not generate ozone, whereas UV lamps at the 185-nm generate ozone through photolysis of oxygen and further reaction, according to the Environmental Protection Agency’s (EPA) “Residential Air Cleaners.”

This new 75-page, comprehensive document outlines the strategies, advantages and disadvantages of all residential air cleaner methodologies. It states that ozone-generating models are detrimental to homeowners’ respiratory tracts, lungs and general health.

Prior to the EPA document’s release, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) had already taken a similar position on ozone-generating air cleaners and their detriment to occupant health.

ASHRAE’s 2015 publication “Position Document on Filtration and Air Cleaning states in Section 2.6: “Ozone is harmful for health and exposure to ozone creates risk for a variety of symptoms and diseases associated with the respiratory tract; Ozone emission is thus undesirable.” Section 3.2 of the document further states: “devices that use the reactivity of ozone for the purpose of cleaning the air should not be used in occupied spaces because of negative health effects that arise from exposure to ozone and its reaction products.”

Still, other organizations have also carved out regulatory ozone requirements for consumers. For example, the U.S. Food and Drug Administration (FDA) was the first to set an ozone emissions limit of 0.05 ppm (50 ppb) for all medical devices.

In 2008, the California Air Resources Board (CARB) targeted ozone emissions with a state-wide regulation requiring certification of all electronic air cleaners under UL 867’s test standard of 0.05 ppm (50 ppb) limit. CARB is expected to soon publish an update on ozone dangers of some air cleaners.

Other Technologies Have Ozone Potential

Besides some types of UV lamps, the EPA has also stated electrostatic precipitators (ESP) and ionizers, which are air cleaning devices positioned in the airstream of HVACR systems, are also potential ozone contributors. Both methodologies use a powered electrostatic process to charge particles, that in turn, become attracted to oppositely-charged plates or other indoor surfaces to remove airborne particulates.

According to the EPA report, “And because ESPs and ionizers use high voltage to generate ionized fields, they may produce ozone either as a byproduct or by design. Ozone is a lung irritant that poses risks to health.”

The report also states that “some makes and models of ESPs and ionizers can increase indoor ozone concentrations that can even exceed public health standards.”

ESPs that use low voltage to generate ionized fields are less likely to produce ozone.

Many air cleaner manufacturers with designs including purposeful ozone generation began substituting their suspect methodologies with marketing terms that omit ozone descriptions. For example, fairly popular terms 10 years ago were ozone generator and ozonator, however those terms are rarely used in air cleaner marketing materials in light of current ozone findings.

This misguided marketing creates expectant and quite undesirable marketplace confusion regarding the amount of ozone generation and off-gassing emissions by several IAQ technologies, products, and brands. Consequently, consumers and even HVACR contractors, who wanted to install the safest products, had nowhere to turn for zero ozone emission confirmation.

Consequently, Underwriters Laboratories (UL), Northbrook, Ill., recently took on the task of creating the desperately needed validation for zero ozone air cleaning devices. UL 2998 is a long-awaited environmental claim procedure with validation. Contractors and consumers can now visit UL SPOT (, which lists all types of sustainable products worldwide.

The UL SPOT’s “HVACR Air Cleaners” section lists validated zero ozone products that emit less than the maximum ozone concentration limit of 0.005 ppm (5 ppb), which is below a quantifiable level for ozone testing. This is 10-fold less than permitted under the aforementioned test standard UL 867. Approved products also receive a validation badge that can be displayed on marketing materials and product labels.

Although the EPA report targets residential systems, contractors should be aware that commercial air cleaning devices can also come under scrutiny.

Consequently, specifying a zero-ozone device may be the difference between winning and losing bids, especially when facility design teams recognize their importance. Zero ozone air treatment device specifications may also someday be required by green building design projects.

Contractors Marketing IAQ

Rick Henson, president, Summer Breeze Comfort Systems, Morgantown, W.Va., formed an IAQ division for his 18-year-old HVACR contracting and service firm in 2012. Now it’s commanding more than a 30-percent share of sales and few competitors have ventured into the niche to compete against him.

Henson made a commitment to the category with a dedicated van thermal-wrapped in photos depicting his IAQ equipment’s advantages. The van is virtually a mobile billboard for his IAQ niche. He implemented the typical direct mailing and brochures that other contractors create, but he took marketing a step further with a walkway kiosk at a local enclosed mall where all his zero-ozone IAQ equipment is on display. There, he can interest new clients how UV disinfects airborne microbes and carbon media air purification neutralizes volatile organic compounds.

Another HVACR contractor, Florida Energy Water & Air (FEWA), Orlando trains and incentivizes its service crews to sell IAQ equipment, such as combination zero-ozone UV and activated carbon media catalyst air treatment products.

Service techs leave IAQ brochures with the homeowner during service calls and answer questions afterward. Currently, the new trend is on-demand IAQ, which uses Internet of Things (IoT) equipment such as air quality monitors that send a signal to the thermostat via Wi-Fi to activate the home’s air handlers, which has an air cleaning device that rectifies the air quality event.

HVACR contractors can be assured ozone discussions will inevitably arise from customers that read the many reports that are surfacing in the media on the dangers of ozone emissions. It would be prudent for contractors to prepare their service people with the factual answers based on the research and refer customers to sources such as the UL SPOT, where they will find a list of validated air cleaning devices that provide air purification with zero ozone emissions.