Nov. 28, 2024
Gas detection is crucial when it comes to monitoring ozone levels in the air, and an ozone detector is the key tool for this purpose. These analyzers measure the concentration of ozone gas in parts per million (ppm), providing essential information for safety and environmental monitoring. However, the unique nature of ozone as an unstable gas presents challenges in detection. Ozone decays to form oxygen based on factors such as temperature, humidity, time, and air agitation, making consistent measurements tricky. To ensure accurate gas detection, it is vital to understand the intricacies of ozone detectors and follow best practices for their use. This guide offers essential information and tips to help users obtain reliable ozone measurements through effective gas detection techniques.
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Pros
Cons
Ozone is highly effective in killing bacteria, fungi, viruses, and molds both on surfaces and suspended in air.
The best ozone detector is the Forensics Detectors Ozone Detector. Why? Because it is calibrated in the USA to NIST traceable sources. This is the only way to be assured of maximum accuracy of your ozone ppm readings.
Ozone is a simple gas made up of three oxygen molecules with the chemical formula O3. It has unique behavioral characteristics. It is an unstable gas and decays to oxygen, meaning that it is tricky to handle and measure.
Ozone is a strong oxidizing agent and offers interesting disinfectant properties to effectively kill fungi, bacteria, and viruses. It is often used in "cleaning" situations. For example, ozone is used in transportation applications to clean police vehicles, transit buses, and commercial passenger aircraft.
Ozone is a special gas because it is unstable and decays to oxygen over time. It cannot be stored in a gas bottle. This unique characteristic makes it tricky to obtain repeatable ozone measurements. Ozone gas also has oxidization properties, making it a useful disinfectant for cleaning and abatement companies. Thanks to ozone's unique therapeutic properties, it is also used throughout medical therapies and applications.
Ozone is measured in the air using low cost gas meters and ozone detectors. These devices cost between $300 and $. Typically, low cost detectors employ electrochemical sensors. These are galvanic cells that output voltages proportional to the ozone concentration. These cells are useful in the ppm ozone concentration range.
More expensive ozone detectors employ ultraviolet (UV) absorption technology. Ozone molecules in the air absorb UV radiation. When the change in light absorption is measured by photodetectors, the detector outputs a proportional electronic signal. UV absorption is the best way to detect low levels of ozone in the parts per billion (ppb) range.
Ozone detectors, meters, and analyzers employ sensor elements to detect O3 gas molecules. These sensors come in three varieties: (1) electrochemical cells, (2) semiconducting metal oxide sensors, and (3) ultraviolet absorption sensors.
Electrochemical Cells
Ozone molecules interact with metal electrodes through a redox reaction, generating a linear voltage output proportional to the ozone concentration.by temperature and humidity
Semiconducting Metal Oxide
Ozone molecules interact with a film of metal oxide material, where surface redox reactions take place. A power-law relationship transpires between the ozone concentration and conductivity of the sensor.
Ultraviolet (UV) Absorption
Ultraviolet light is emitted and absorbed by ozone at 254 nm. The absorption is detected with a photodetector. Using the Beer-Lambert law, the UV absorption and ozone concentration is determined.Various government agencies have recommended ozone gas exposure limits and emission levels. Some examples are shown in the table below.
0.3 ppm over 15minutes
National Institute for Occupational Safety and Health (NIOSH)
0.1 ppm 5 ppm IDHL Immediately Dangerous To Life or Health US Environmental Protection Agency (EPA) 0.07 ppmFood and Drug Administration (FDA) - ozone output of indoor medical devices 21CFR801.415
0.05 ppm output & accumulationAmerican Conference of Governmental Industrial Hygienists (ACGIH)
0.1 ppmUL - Environmental Claim Validation Procedure (ECVP) for Zero Ozone Emissions from Air Cleaners
0.005 ppmUL867 - Standard for Electrostatic Air Cleaners
Any device that requires power to clean the air
0.05 ppmAmerican Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) Environmental Health Committee
0.01 ppmCalifornia Air Resources Board (CARB) ozone emissions electronic air cleaners
0.05 ppm
No, it is not. If you inhale ozone, a cough response is immediately triggered. The National Institute for Occupational Safety and Health (NIOSH) has established the Immediately Dangerous To Life or Health ozone concentration as 5 ppm.
When working with ozone, make sure you are in a well-ventilated area and have a personal ozone meter to warn you of high levels.
More on the health effects of ozone can be found here.
Ozone has a familiar photocopier room smell. You may not have noticed it, but the ultraviolet light emits ozone in photocopier rooms or when you print a lot of pages at home.
The ozone odor is sometimes described as a "clean," electric smell.
No, you cannot. Although your nose can detect very low levels of ozone < 0.02 ppm, the nose quickly adapts and experiences olfactory fatigue.
Olfactory fatigue is used to describe losing sensitivity to specific odors after exposure. When continuously smelling the same scent, your nose and brain will adapt and lose sensitivity to that smell over time. Eventually, you will not recognize the odor, hence the term olfactory fatigue.
Olfactory fatigue will dissipate when the smell is removed, so your sensitivity will return to normal after some time. Each person has different sensitivities to different smells, which also varies with age.
All in all, don't bother trying to correlate the potency of ozone scent to a particular amount of ozone. It simply is not a reliable method of detection.
Yes, it can. Ozone is a strong oxidizing agent that can kill bacteria, molds, fungi, and viruses.
When ozone generators or electrostatic air purifiers create ozone, the gas can reach every corner in the room, making it a very effective and residue-free approach compared to spray or chemical methods.
The efficacy in killing microorganisms like bacteria, fungi, and viruses depends on the ozone concentration, exposure time, temperature, humidity, and air agitation.
All in all, ozone is comparable to other disinfectant methods, such as UV light and chemical disinfectants.
When using ozone to kill pathogens, there are two components that must be determined: (1) concentration and (2) exposure time. Many resources have developed efficient protocols for a variety of pathogens, but each has its intricacies. We recommend referencing the latest literature in the field using Google Scholar. As a guide, here are some examples:
There are many uses of ozone detectors. Some examples include:
Portable ozone detectors are clipped onto workers to provide personal protection, ensuring safe exposure levels. For example, ozone is used to disinfect aircraft. When workers are cleaning, portable ozone detectors provide protection from elevated levels of ozone exposure.
Portable ozone detectors are used to verify ozone concentrations in crop grow rooms. This ensures high yield and destroys pathogens such as fungi, microbes, bacteria, and viruses. High range ozone detectors are occasionally required for this purpose.
Many water treatment facilities employ ozone to disinfect storage containers. On a production line of small units, wall-mounted ozone monitors are placed to protect employees from equipment malfunctions and large ozone emissions.
Ozone has many medicinal benefits, as it is used to disinfect and treat disease. It inactivates bacteria, viruses, fungi, yeast, and protozoa. Ozone has also been used to treat diseases such as infected wounds, circulatory disorders, geriatric conditions, macular degeneration, viral diseases, rheumatism/arthritis, cancer, SARS, and AIDS. Therefore, portable low-level ozone gas detectors are required by medical workers to ensure they are working within safe ozone exposure limits.
In order to select the best ozone detector, follow this guide. To understand your application and narrow down your selection, answer these questions:
Examples of some real ozone detector applications used by our customers:
Ozone (O3) is a unique gas and cannot be calibrated with a calibration bottle setup like most gases. As ozone is an unstable gas, it cannot be stored at a fixed concentration in a gas cylinder.
Therefore, ozone must be generated on-site. The produced ozone must be calibrated to a NIST traceable source to ensure correct calibration. Only a few laboratories in the USA have the expensive, NIST calibrated equipment required to perform ozone detector calibration.
As an example, the Forensics Detectors Ozone USA NIST Traceability Procedure is highlighted here. Forensics Detectors provides ozone calibration services, which can be purchased here.
Bump testing is a procedure when the user exposes the ozone detector to a small amount of &#;blast&#; gas to ensure the detector operates and alarms as programmed.
The function of this test is to verify proper operation and build user confidence, particularly in hazardous applications. It is recommended to bump test your ozone detector when first purchased, followed by weekly tests. This is especially important in LIFE- THREATENING and / or DANGEROUS applications. See video explanation here.
Ozone bump testing is performed using a small ozone generator.
When operating an ozone detector, there are some important tips to consider given the unique nature of ozone. Be smart, read your product manual, and keep the following tips in mind:
There are two types of ozone detectors:
When possible, it is best not to agitate the ozone and use diffusive detection. This is because as ozone tends to decay more quickly when agitated. In other words, the ozone breaks down faster. A pump or probe accessory may be required for point sampling. In this case, the addition of the pump or probe will agitate the ozone and increase its decay time, reducing the detected ozone concentration. Be aware of this effect as we always get the question, "why am I detecting less ozone when I attach the probe?"
Avoid any accessory pumps or probes and only use them as necessary to ensure maximum accuracy. If you plan to use a probe, there are two things you should do:
If you want to learn more, please visit our website ozone monitoring equipment.
Low cost ozone detectors in the ppm range cannot measure outdoor ozone levels. This is a classic mistake we sometimes see our customers making. A generic 0- 20 ppm detector with 0.1 ppm resolution will not be able to detect atmospheric ozone.
The outdoor ozone concentration is in the parts per billion (ppb) concentration range. To detect ozone in the ppb range, you need a UV absorption analyzer. UV detectors are the only devices that can reliably and accurately measure ozone in the ppb range. This is a sophisticated piece of equipment that requires technical training to operate properly. In addition, UV analyzers are very expensive. Technical considerations such as temperature, humidity, and sampling techniques are required to ensure consistent and accurate measurements.
If you are a novice and are curious about your outdoor ozone levels, we recommend using Airnow. Enter your zip code to obtain the ozone levels from your local air quality station.
No, not likely. Ozone generators typically produce thousands of ppm of O3. Do not use your standard (0 - 20 ppm) detector to test the output of your ozone generator as it will permanently damage the sensor. Only use an ozone detector to test the output if you are absolutely certain the range of the meter is within the output range. For example, if you have a custom built ozone meter with a range from 0 - 10,000 ppm, then testing ppm of ozone will be OK.
However, ozone generators are typically at an ozone output of mg/hr or g/hr. See the next section to convert to ppm and determine the expected ppm range - which will then help narrow down the appropriate ozone detector range.
Customers with an ozone generator typically wish to purchase a detector to determine the output concentration. Ozone generators produce very high concentrations of ozone, often close to or over ppm. Be careful not to place the ozone detector at the output of any generator. You will blow it out!
Ozone generators are typically rated on ozone output based on gravimetric and time metric units, such as a mg/hr. This can be converted to ppm using the conversion factors below:
1 ug/mL = 1 mg/L = 1g/m3
1 g/m3 = 1 mg/L = 1 ppm of ozone in water (mass)
1 g/m3 = 467 ppm of ozone in air (volume)
1 ppm = 2.14 mg/m3 in air (by volume)
Let's consider an example:
What is the ozone concentration in ppm at the output of my ozone generator with a 200 mg/hour @ 2 LPM rating?
So at 2 LPM (liters per minute), after one hour, there would be 2 x 60 = 120 liters emitted since there are 60 minutes in one hour.
Within the 120 liters, there are 200 mg of ozone generated. So, we need to obtain a mg/L unit. A simple division of 200 / 120 = 1.67 mg/L.
From the conversions, we know that 1 mg/L = 1 g/m3, therefore:
1.67 mg/L = 1.676 g/m3
therefore, knowing that:
1 g/m3 = 467 ppm of ozone in air (volume)
then,
1.676 g/m3 = 780 ppm.
Final Words
Gas detection for ozone is the most challenging among all gases due to its unique physical properties. When selecting an ozone detector, it is crucial to conduct thorough research and ask detailed questions, particularly about NIST ozone traceability calibration, as not all detectors are created equal. For most applications, low-cost electrochemical cells provide adequate gas detection capabilities. However, if measuring ozone in the parts per billion (ppb) range is necessary, investing in a UV analyzer, which typically costs over $, is essential. Proper research and understanding of the specific gas detection requirements are vital to ensure accurate and reliable ozone measurements.Dr. Kos Galatsis ("Dr.Koz") is the President of FORENSICS DETECTORS where the company operates from the scenic Palos Verdes Peninsula in Los Angeles, California. He is a subject matter expert on gas sensor technology, gas detectors, gas meters and gas analyzers. He has been designing, building, manufacturing and testing toxic gas detection systems for over 20 years.
Every day is a blessing for Dr. Koz. He loves to help customers solve their unique problems. Dr. Koz also loves spending time with his wife and his three children going to the beach, grilling burgers, and enjoying the outdoors.
Read more about Forensics Detectors here.
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Gas detection for ozone is the most challenging among all gases due to its unique physical properties. When selecting an ozone detector, it is crucial to conduct thorough research and ask detailed questions, particularly about NIST ozone traceability calibration, as not all detectors are created equal. For most applications, low-cost electrochemical cells provide adequate gas detection capabilities. However, if measuring ozone in the parts per billion (ppb) range is necessary, investing in a UV analyzer, which typically costs over $, is essential. Proper research and understanding of the specific gas detection requirements are vital to ensure accurate and reliable ozone measurements.
TL;DR &#; The US EPA&#;s Enhanced Air Sensor Guidebook outlines recommendations when it comes to choosing the right air quality monitoring equipment for your project. By taking into account the specific features of different low-cost sensor technology &#; such as the device&#;s accuracy and reliability, the pollutants it can monitor, its ease of use and maintenance requirements, and its data analysis capabilities &#; you can choose the air quality monitoring equipment that will be most effective for your project goals.
This blog is part of a series that highlights key themes from the US EPA Enhanced Air Sensor Guidebook, whose updated version was published in . The guidebook covers a variety of topics involving low-cost air quality sensor use.
Today, we&#;ll be breaking down the Guidebook&#;s recommendations when it comes to selecting the right air quality monitoring equipment for your project.
A variety of air quality monitoring equipment exists with various types of low-cost sensors now available.
However, these technologies vary in their different specifications &#; such as accuracy and durability &#; making it important to carefully select the appropriate air quality monitoring equipment for your project and its goals.
Both accuracy and reliability are important parameters to consider when it comes to determining the data quality of different low-cost sensor technologies.
Accuracy describes how well the sensor&#;s measurements of any given pollutant match the measurements from a reference-grade monitor. In contrast, reliability refers to how consistent the sensor&#;s measurement points are to each other, rather than to that of the reference device.
The accuracy of a sensor is determined by precision and bias. Precision is how well the sensor reproduces the measurement as compared to the reference monitor under the same environmental conditions. Bias describes the amount of measurement error in the measurements &#; that is, whether they are higher or lower than the true concentration, and to what degree.
To learn more about measurement error, check out our blog covering mean absolute error (MAE) here.
The image above displays different scenarios of air quality data measurements, where the low-cost sensor varies in precision and bias as compared to the reference instrument. Having less bias and more precision means the sensor is collecting the most accurate measurements. (Image source: US EPA Enhanced Air Sensor Guidebook)You can learn more about evaluating sensor accuracy and reliability by checking out our blog series here.
It is important to look for a sensor that has documented accuracy and reliability under similar environmental conditions to those it will be operating in, ensuring it will collect high-quality data during the operation of the monitoring project.
It is essential to choose air quality monitoring equipment that will measure all potential pollutants of interest at the ranges that the network will likely detect over the course of the monitoring project.
The Clarity Node-S measures particulate matter (PM) and nitrogen dioxide (NO2), with add-on modules available for other air quality measurements, like wind and ozone.
Additionally, it is important that the sensor technology can detect both high and low concentrations, as the pollutant concentrations that the sensor may come across during monitoring can vary widely.
Ease of use is important to consider because different individuals with a wide array of experience and technical knowledge may need to operate a sensor.
If a skilled technician or other expert is needed, this can also factor into the operating costs of the network.
Maintenance involves how often repair or replacement is needed, what calibration services must be kept up, and how durable the sensor is, among other factors.
Consider the requirements of your specific sensor technology and the costs associated with it.
Clarity&#;s Node-S air quality sensor is solar-powered and cellular-connected, leading to fewer maintenance requirements and therefore lower costs.Choosing the right technology does not end with the hardware specifications &#; it&#;s equally important to choose an air quality monitoring solution that meets your project&#;s needs for data processing. Consider both the technology&#;s calibration process &#; to ensure that accurate data is collected &#; as well as the platforms where data will be presented and visualized.
For more information, read our blog covering calibration and its importance here.
Data handling and access are also important. You should consider:
At Clarity, our Clarity Cloud houses the Node-S air quality measurements, which are uploaded via a cellular connection.
Data can be accessed via the Clarity Dashboard which allows for data to be managed and visualized, with both raw and calibrated data easily accessible. By having a platform that allows for easy data access and management, you can reduce the time you spend on processing data and focus on making an impact with your air quality monitoring data.
The cost of different air quality monitoring sensors can vary widely.
It is important to consider both upfront or purchase costs as well as what the operational costs of the sensors will be over the long term.
By minimizing the operational costs associated with maintaining an air quality monitoring network, Clarity&#;s Sensing-as-a-Service model makes it possible for anyone to collect reliable, high-density air quality data at a fraction of traditional costs. This makes it economically feasible to scale air quality monitoring networks to dozens, hundreds, or even thousands of measurement points.
Consider what data quality and specifications &#; such as data transmission and storage, calibration services, et cetera &#; are needed for your specific air quality monitoring project.
Logistically, it is important to choose equipment that matches what can be provided in the environment. This may involve power needs and connectivity requirements, which vary widely depending on where the sensors will be sited.
Read our blog on siting and installing low-cost sensors to learn more about the requirements that different sensors may have.
Durability is also an important factor to consider, as different environments will put different amounts of wear and tear on the sensor. Consider what conditions the sensors in your monitoring project will need to withstand over the course of their use.
Different types of monitoring projects, businesses, and organizations will benefit from thoroughly evaluating the right type of air quality monitoring equipment for them.
The Denver Department of Public Health and Environment (DDPHE) wanted to be able to quickly and flexibly respond to potential air pollution hotspots in their city.
They rapidly deployed Clarity Node-S devices during protests on social injustice in order to assess the possible impacts of air pollution on public health during this event.
The flexibility and ease of deployment of low-cost sensors allowed for their rapid deployment, and their low cost meant that more sensors could be used in order to collect more hyperlocal, high-resolution data.
Read more about our work with Denver here.
Groundwork Richmond had the goal of establishing an air quality monitoring network that could collect more real-time, local air quality data in order to support the longstanding concerns of residents. The city has long experienced high levels of air pollution due to a refinery and freeways running through the community, and residents have suffered the consequences on their health.
Officials at Groundwork Richmond wanted monitors that did not need a dedicated electricity supply so that they could be more flexible in where they were sited. This meant that monitors could be deployed in the locations that were most important to community members.
They also wanted sensors that would not go offline in case of power outages, making Clarity Node-S devices a great pick for them.
Read more about our work with Groundwork Richmond here.
It is highly important to thoroughly evaluate potential air quality monitoring equipment to make sure that it will be suitable for your specific project goals and needs. In doing so, you will ensure the best bet for success for your air quality monitoring network.
Interested in measuring air quality for cleaner air, improved physical and mental health, and a healthier climate? Get in touch with our team to learn more about our Sensing-as-a-Service solution for governments, businesses, and community organizations, using our Clarity Node-S monitors and modules that do not depend on infrastructure like WiFi or power &#; making them especially resilient during environmental disasters.
For more commercial ozonatorinformation, please contact us. We will provide professional answers.
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