People will often call us asking how to measure ozone levels in their houses. A couple years ago, we wrote an article about using ozone badges to measure ozone levels in houses. While ozone badges are a great option, today we are going to look at using an ozone monitor for the same purpose.
There are many different ozone monitors that would work well to measure ozone in your house. We are going to take a look at the EZ-1X. The EZ-1X is great for homeowners and cleaning companies because it measures up to .14 ppm of ozone and is inexpensive.
Once you have obtained an EZ-1X, you will need to follow these steps to ensure accurate readings:
Plug in the EZ-1X to a wall outlet and let it warm up for 15 minutes. The monitor won’t give accurate readings until it has warmed up for 15 minutes.
While you are waiting 15 minutes, read the manual! These instructions are good, but the manual has many more details. Besides, it’s only 2 pages, you can read that in 10 minutes!
Decide where in your house to measure ozone. The best place to measure is at breathing level; ozone is heavier than air and will sink to the floor. This means that the concentrations of ozone can be much higher near the floor than they are at breathing level. If you are measuring for safety purposes, it is best to take measurements at breathing level.
Place the EZ-1X at the location where you have decided to measure the ozone. Leave the monitor in one location for a couple minutes to ensure accurate readings.
Look at the lights on the monitor and record the reading. Red indicates ozone levels that are too high for humans to remain in the area.
It is a good idea to get a measurements from a couple other locations in the house since concentrations can vary from location to location.
The colored lights make it easy to read the ozone level at a glance.
Here are a couple things to keep in mind:
If the ozone level is at or above .14 ppm, you should leave the area immediately. Since the EZ-1X only reads up to .14 ppm, the ozone level could be much higher and dangerous. See our page on Ozone Safety for more information.
Your nose is not an ozone monitor! Although you can smell ozone, your nose gets less sensitive to ozone over time and is not a good way to check the levels of ozone.
Other gasses can interfere with the EZ-1X. This includes chlorine and vapors from solvents. If you need to measure ozone while these gasses are present, you will need a UV ozone analyzer.
If you have the need to control ambient ozone levels, Ozone Solutions provides several options that helps you achieve ozone generator safety. An ozone monitor with integrated relay outputs would be needed to achieve this. Sometimes these monitors are also referred to as ozone controllers or ozone switches. The majority of the ozone monitors we provide, include relay outputs.
Relay Outputs inside of the ES-600.
Ozone monitors with relay outputs could be used to turn off/on an ozone generator, a fan, audible/visual alarms, or even an ozone destruct unit when the monitor reaches a specific concentration. Some of the monitors we provide strictly engage relays at the .1 PPM OSHA safety limit, and others allow you to engage the relays at any point within the sensors operating range. Since the integrated relays are rather small, we recommend using these relays to engage larger relays with a higher current rating. Ozone Solutions also provides products that are easily connected to an ozone monitor to switch on and off a 120 Volt outlet.
If you are interested in using a relay output to monitor your levels of ozone, check out our information page Controlling Ozone Levels.
Listed below are just some of the ozone monitors we offer that would work for this application.
For this week’s Wednesday | Weekly Product to Watch we are looking at the C-30ZX ozone monitor. This small device packs quite the punch! With data output, audible alarm, and control relay, this monitor strikes a great balance between capability and economy. This is a great monitor for people looking to do more than just measure ozone. We have compiled a list of the top 5 things to do with a C-30ZX:
Measure Ozone! This monitor can read ozone levels from 0.00 – 0.14 ppm. This is great for measuring ozone in occupied rooms.
Set Up Alarms: The C-30ZX has a configurable alarm to alert you when the ozone level has gotten too high. When the ozone exceeds the level you set, the alarm sounds and the area can be evacuated.
Control an Ozone Generator: Equipped with a relay, the C-30ZX can automatically power off your ozone generator. By connecting the relay to an ozone generator, you can ensure that your generator will shut off once a certain level of ozone concentration has been reached.
Control Exhaust Fans: Not only can you use the built in relay to control an ozone generator, you can also control vent fans (or anything else you can hook up to a relay)! By hooking a vent fan up to the C-30ZX, you can make sure your vent fan kicks on only when it’s needed.
Record Ozone Levels: The C-30ZX has an analog data output allowing you to digitally record the ozone levels over time. By using a data logger like the DL-2, you collect data on your ambient ozone levels. This is great for troubleshooting, ozone research, and ensuring employee safety. Rather than guessing what the ozone levels are, you can know!
Colorado Medical Waste, Inc., announces that Colorado has become the third state in the nation to adopt an environmentally safe technology for the processing of medical waste. The new green technology, using ozone to process medical waste with no environmental contaminants, is positioned to make noxious medical waste dumping a thing of the past.
Following approvals by the City of Aurora, Metro Waste Water Reclamation, and the Colorado Department of Public Health and Environment (CDPHE); final approval was granted on March 10 for operation of the Ozone Medical Waste Processor at the company’s Aurora location.
Colorado Medical Waste is the first in Colorado to adopt this technology. President Beverly Hanstrom has worked for more than three years to obtain regulatory approvals to operate her Ozone Medical Waste Processor. “We are ecstatic to finally put this amazing technology to work for Colorado,” says Hanstrom. “Ozone medical waste processing is the future and will replace antiquated technologies and processes of the past. It’s been a long time coming, and we are poised and positioned to accommodate five tons per day and have planned in advance for the installation of another ozone processor as volume increases.”
Several news stories have hit the headlines lately regarding ozone exposure incidents. For the most part, these have involved contractors or employees that were not directly involved with the use of ozone at these facilities. In other words, the individuals exposed were not familiar with the basics of ozone safety, but they were exposed to ozone nonetheless.
While these incidents can certainly become overblown by mainstream media (as media will do), that makes them no less significant to the ozone industry – it is public perception that counts. Where truth and media coverage collide, media coverage always has the upper hand. The matter is complicated further when ozone exposure incidents lead to civil suits – miring ozone-use facilities and ozone manufacturers in substantial legal expense and additional bad publicity.
Unfortunately, it is possible that these recent incidents could have been avoided if more care had been given to proper ozone detection equipment and proper ozone safety procedures. Whether you have a facility using ozone or are a manufacturer producing ozone systems, this is a lesson that needs to be taken to heart.
OSHA requirements dictate that ozone levels cannot exceed 0.1 ppm, so for the sake of expense many organizations implement a single monitor to satisfy the regulation. As applications for ozone increase, however, the number of individuals that work in the vicinity of ozone systems will also increase. While the increasing number of individuals does not increase the likelihood of an ozone leak, it does increase the likelihood of exposure if a leak does occur. For that reason, the extent of ozone safety equipment and training at a facility should instead be based on the likelihood of exposure – not just OSHA regulations.
What does this mean, exactly? Take these examples:
At a small company where all employees are familiar with ozone and fully trained in the use of their ozone system, a single or small number of monitors may be sufficient for employee safety. (As always, this also depends on proper maintenance, adherence to proper procedures, etc.)
At a large company, there may only be a handful of employees that use an ozone system and are familiar with its use. These organizations should implement additional ozone monitors and safety signage in any area where “non-ozone” employees may be present. This helps ensure that all employees in all areas can remain safe and act appropriately in the event of an ozone leak.
Public facilities need to take their safety measures one step further. In a facility where the general public could be exposed to an ozone leak, all areas need to be monitored (with redundancy where possible), proper maintenance should be observed, ventilation should be present, ozone equipment rooms should have limited access and staff should be trained in how to handle an ozone leak.
Regardless of how careful a company is, ozone leaks are a reality. As users of ozone equipment, please keep this in mind as you plan your ozone systems and then communicate your safety requirements to us as we help with the design process. As a manufacturer, Ozone Solutions will continue asking questions to ensure that the equipment we sell is being sold with proper detection equipment installed. Together we can help the ozone industry continue its stellar record of safety for another 100 years.
To sum up our ongoing series comparing ozone detection technologies, here is a full list that summarizes the advantages, disadvantages and common applications for various ozone monitor technologies. For further information, visit the Ozone Monitor Technology Comparison page on our website and then browse our product pages for details!
Electrochemical Ozone Sensors
An electrochemical ozone sensor uses a porous membrane that allows ozone gas to diffuse into a cell containing electrolyte and electrodes. When ozone comes into contact with the electrolyte, a change in electrochemical potential occurs between the electrodes causing electrons to flow.
In “zero air”, little or no electron flow occurs. As the presence of ozone increases, the electrical signal increases proportionally. The monitor interprets this signal and displays the ozone concentration in PPM (parts per million).
Good repeatability and accuracy
Very quick response time (1-2 seconds)
Long battery life
Can measure ozone accurately up to 20 ppm
Moderate resistance to interference
Humidity can affect sensor
Sensitive to EMF/RFI
Limited sensor life (12-18months), even if in storage.
Less accuracy at low ozone levels (below 0.1 ppm)
Personnel (portable) safety monitoring (esp. long shifts)
Ozone Leak Detection
Stationary ozone monitoring
Ozone Monitoring & Control
Semiconductor-Based Ozone Sensors
Heated Metal Oxide Sensor Cell (HMOS)
Gas Sensitive Semiconductor (GSS)
A heated metal oxide semiconductor (HMOS) sensor works by heating a small substrate to high temperature (around 300-deg F / 149-deg C). At this temperature, the substrate is very sensitive to ozone and exhibits a change in resistance that is proportional to to the amount of ozone which contacts its surface. The circuitry of the monitor interprets this change in resistance and displays the corresponding ozone level on the display as either PPM or PPB.
Very responsive to low levels of ozone ozone (below 0.1 ppm)
Slower response time to ozone (compared to electrochemical)
Very sensitive to interference
Shorter battery life due to heated sensor element
Not linear at ozone levels above 1 ppm
Ceiling Temperature threshold of 122F or less (depending on model)
The Ozone molecule has an absorption maximum at 254 nm. A UV lamp emmiting 254 nm wavelength of light is used to measure the absoption of ozone within a chamber. This is measured via a photodiode with a built in interference filter centered on 254 nm wavelength
Very accurate (within 1%)
Very linear at any ozone levels
Low ppb detection limits with accuracy
Minimal cross sensitivity to other gasses or interferences
Can read high concentrations (20% or higher)
Durable design with excellent longevity
Bench mount (no handheld)
Ozone badges are one time use cards that use a color change indicator. The indicator used is a small paper strip or circle that is oxidized in the presence of ozone.
There are three primary technologies used to monitor and measure ozone: Electrochemical cells, HMOS / GSS, and UV. Today we will be giving a brief overview of UV ozone analyzers and their use.
UV-based ozone analyzers function on the principle that ozone particles will absorb UV light with a wavelength of 254 nm. When this wavelength of UV light is created and passed through an air chamber, the amount of UV light absorbed is proportional to the amount of ozone present in that airspace. The amount of UV light absorbed in the chamber is interpreted as ozone concentration and displayed or output for our use.
There are many advantages to this technology, but the primary ones are its accuracy and stability over a wide range of ozone concentrations. Depending on the design of the instrument, a UV ozone analyzer may be able to provide reliable, stable readings for single-digit ppb concentrations of ozone. Alternately, another UV analyzer may provide high concentration readings up to 20% by weight (many thousands of ppm).
Another benefit of UV Absorption is its resistance to interference by other gases. Since the principle used is very wavelength-specific, few other gases interfere. This results in much more accurate readings, even in outdoor environments.
The most noticeable downside of UV Absorption technology is price. It is more expensive than HMOS, GSS or electrochemical technologies. For many customers, however, the reliability of UV technology compared to the risk of false readings from other monitors makes UV technology well worth the cost.
Industrial ozone control
Ozone process off-gas measurement
Semiconductor fabrication facilites
Ozone compatibility testing
Here are a few monitors offered by Ozone Solutions that utilize UV Absorption technology:
There are three primary technologies used to monitor and measure ozone: Electrochemical cells, HMOS / GSS, and UV. Today we will be giving a brief overview of Electrochemical sensors and their use.
When ozone contacts an electrochemical cell, it causes electrons to flow. This electric current varies in proportion to the amount of ozone present, so the monitor can interpret this signal as ozone concentration and display or output those values for us.
Due to their construction, electrochemical ozone monitors have several properties that make them unique. One of these is long battery life. Due to the low power consumption of their sensors, they have the longest battery life of any ozone monitoring technology.
Another benefit they share is a resistance to interference from other gases. Electrochemical cells are each built with materials that are designed to be as specific to ozone as possible. While not as good as UV technology in this regard, there are certain situations where they are a necessity.
One downside that these sensors have in common, however, is their limited sensor life. Electrochemical cells will deplete over time even while in storage, so keeping a regular replacement schedule is advised.
Portable ozone safety monitoring
Ozone monitoring & control, especially if interfering gases are a concern
Here are a few monitors offered by Ozone Solutions that utilize Electrochemical Sensor technology:
There are three primary technologies used to monitor and measure ozone: Electrochemical cells, HMOS / GSS, and UV. Today we will be giving a brief overview of HMOS / GSS sensors and their use.
HMOS (Heated Metal-Oxide Semiconductor) and GSS (Gas-Sensitive Semiconductor) based ozone sensors function by heating a small semiconductor substrate to high temperatures, causing it to be extremely sensitive to ozone. This is seen as a change in the resistance of the material, which is measured by the circuitry, interpreted as ozone, and either displayed or output for our use.
One of the key benefits of this sensor technology is that it is very inexpensive, allowing widespread adoption at many facilities. It is commonly used for both portables and wall-mount ozone monitors.
Another advantage to semiconductor-based sensors is their solid ozone response below 0.1 ppm. This allows them to be used in many ambient ozone safety scenarios, with a display resolution as fine-grained as 1 ppb. While not as stable or sensitive as UV-based ozone analyzers in this range, they are worth consideration for ambient safety scenarios where low ozone concentrations are expected.
Disadvantages include a short battery life (due to the continuous heating of the sensor) and the extended warm-up time that the sensor requires.
Ambient ozone safety monitoring
Ozone control scenarios, especially at levels below 0.1 ppm
Here are a few monitors offered by Ozone Solutions that utilize HMOS Sensor technology:
One question we commonly receive is “Do your ozone monitor calibrations come with NIST traceable calibration certificates?” The answer is simply yes, our ozone monitor calibrations (and our ozone analyzer calibrations) do indeed come with NIST traceable calibration certificates.
Another question we receive somewhat less often is, “What IS a NIST traceable calibration?” We will discuss that topic briefly here.
To start out, NIST is the National Institute of Standards and Technology, which was founded in 1901 and is responsible for governing national standards of measure here in the United States (among other things). From the NIST website:
NIST is responsible for developing, maintaining and disseminating national standards - realizations of the SI – for the basic measurement quantities, and for many derived measurement quantities. NIST is also responsible for assessing the measurement uncertainties associated with the values assigned to these measurement standards. As such, the concept of measurement traceability is central to NIST’s mission.
Traceability, then, refers to your ability to follow documented calibration paperwork in an unbroken chain all the way back to the official NIST standard itself. The calibration certificate for any ozone monitor should list the source that it was calibrated against. If you obtain the calibration sheet for that source, you will again find the source that it was calibrated against and so on and so on. If you follow the chain, you will eventually find a calibration source that was calibrated at NIST itself.
Note that with each “hop” of the traceability chain there is some amount of uncertainty that is added to the resulting calibration. The more “hops” from NIST, the larger the uncertainty. The length of the traceability chain will give you an indication of how much uncertainty you may encounter as compared to the NIST standard.
What is the benefit of all this paperwork? One standard. The NIST ozone standard is deemed to provide the one, true standard for an ozone measurement. As consumers, if you purchase an ozone monitor that has a NIST traceable calibration certificate, you can rest assured that the measurements indicated by your ozone monitor should be comparable to a true ozone measurement.
When you purchase a piece of ozone detection equipment from Ozone Solutions, or when you have ozone monitors calibrated at Ozone Solutions, you will receive a NIST traceable calibration certificate which indicates our dedication to quality ozone detection products and quality service. Ozone Solutions prides itself in having a short NIST traceability chain, minimizing uncertainty to provide the most accurate ozone readings possible.
For further information on our calibration process, please refer to the following links:
This Ozone Journal is a blog managed by the employees of Ozone Solutions. The purpose of this blog is to inform and educate the readers about the world of Ozone, provide news about the ozone industry, and have an easy opportunity to inform about new ozone products.
Check back often, ask questions, and let us know if there is anything you would like to hear about.
What is ozone?
Ozone is an oxidant. Ozone (O3), sometimes called “activated oxygen", or "triatomic oxygen", contains three atoms of oxygen rather than the two atoms we normally breathe. Ozone is the second most powerful oxidant in the world and can be used to destroy bacteria, viruses, and odors.
Ozone is a gas at ambient temperatures and pressures with a strong odor. Ozone can be produced as a gas from oxygen in air, or concentrated oxygen. This ozone gas can be dissolved into water, or used in the gas phase for a variety of applications discussed in this Journal.