AirGradient ONE Enclosure Top View

AirGradient ONE - Award Winning Indoor Monitor

Indoor Air Quality Monitor

The AirGradient ONE (Model I-9PSL) is an indoor air quality monitor enabling you to know if the air quality is healthy or not. It measures PM1, PM2.5, PM10, CO2, TVOCs, NOX, Temperature and Humidity and has a built-in color LED bar and small display.

It’s fully open-source and customizable, so you can extend it in whatever way you like.

Now with native Home Assistant support.

Get It From Us

We Launched the Largest Real-Time Global CO2 Map

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Why Indoor Air Quality Matters

We spend 80% of our time indoors, and the indoor air is often polluted not only from sources outside your home but also from indoor pollutants like off-gassing furniture, cooking, and cleaning chemicals. Also, houses with insufficient fresh air ventilation can have very high CO2 levels that can cause headaches and tiredness and greatly impact cognitive performance.

Measuring these air quality parameters can help you identify pollutants and, step by step, create a healthy and comfortable indoor environment.

Key Characteristics

AirGradient ONE Features

AirGradient uses high-quality sensor modules from industry leaders like SenseAir, Sensirion, and Plantower. Every sensor goes through a multi-step testing and calibration process to ensure the highest accuracy.

The SenseAir S8 CO2 sensor utilizes NDIR technology for very accurate measurements. It auto-calibrates with an automatic baseline calibration (ABC) every seven days (customizable). High levels of CO2 can indicate insufficient ventilation and cause headaches, tiredness, and lower cognitive performance.

For PM2.5 measurements, the AirGradient uses the Plantower PMS5003 sensor with laser scattering technology, which has been extensively tested in various studies. Elevated levels of fine particles - especially below 2.5 microns - have been linked to a wide range of health issues, including premature mortality, heart or lung problems, acute and chronic bronchitis, asthma attacks, and respiratory symptoms. The sensor module is factory-calibrated.

TVOCs and NOX are measured with the Sensirion SGP41 TVOC/NOX sensor. TVOCs are organic chemicals that can easily vaporize and enter the air we breathe. These often have indoor causes like off-gassing furniture or aggressive cleaning liquids. NOX are harmful gases caused by indoor gas stoves or boilers. The measurements are based on the Sensirion VOC Index and represent changes and relative developments in VOC concentrations rather than absolute values. Please note that harmless substances like ethanol or sunscreen also trigger VOCs. So, an elevated value does not necessarily mean a harmful event.

Temperature and Humidity are measured with the Sensirion SHT3x/4x sensors, some of the most accurate in the market. These two air quality parameters can give you good information about indoor comfort levels and also indicate, for example, the risk of mold due to high humidity levels.

The monitor has a built-in OLED display to show the current air quality and can also be connected to 2.4 GHz WiFi networks to communicate with data platforms.

Additionally, the monitor has 11 RGB LEDs that shine through the enclosure and can be programmed to show you different color bands, e.g. for CO2 or PM. They can also be completely switched off.

We work very closely with several leading universities on air quality monitoring, and, due to its performance and affordability, our monitor has been selected for the largest study of classroom air quality in the world. You can read more about our work with research institutions on our research page.

Flexible Data Platforms & Home Assistant Support

AirGradient Dashboard with Data Shown

The AirGradient monitor is unique as it gives you full flexibility in monitoring and using your data. Being open-source, you are not locked into any specific data platform but can connect the data to any server or use the AirGradient data platform - a data platform specifically made for air quality monitoring.

This gives you complete ownership and freedom of your data, and our community has built several extensions to existing data platforms like ESPHome, Prometheus, and openHAB.

From Home Assistant 2024.6 onwards (and running the latest firmware), the AirGradient ONE now natively supports Home Assistant and will get auto discovered.

Of course, you can also use the AirGradient dashboard, which is already pre-flashed on the monitor and very easy to set up.

This powerful dashboard lets you immediately see the air quality and environmental status of multiple locations. It is built for speed and scale. You can set up specific alerts and get notified automatically if air quality exceeds your defined ranges.

Get powerful daily and weekly reports detailing the air quality of each location, providing you with a clear, concise summary at a glance.

Outdoor monitors can also be displayed on the AirGradient Map, and you can opt-in to share your outdoor data with openAQ, a non-profit that aims to democratize air quality data and make it freely available.

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Mounting Options

AirGradient PRO Mounting Instructions

The monitor can be mounted on walls or put on a desk with the optional clip-on stands. For wall mounting, the screw distances are compatible with common European or US junction boxes. The USB C cable is connected to the back of the monitor, and the cables can come in from either the top or the bottom of the enclosure.

Easy to Assemble, Setup & Install

The kit version is very easy to assemble. We provide detailed instructions and videos on connecting the monitor to your WiFi network and set it up on the dashboard and map. If you have any problems, just contact us directly; we are happy to help. You can also ask questions in the AirGradient Forum and get valuable tips from the community.

Optimized Enclosure

AirGradient PRO Enclosure Features

The enclosure has been designed with two primary goals: first, to ensure accurate measurements of the air quality and second, to be robust and long-lasting.

For accurate measurements, it is important that there is good airflow to the sensor modules, that air loops in front of the sensor modules are avoided, and that the risk of condensation inside the enclosure is reduced as much as possible.

The enclosure is very robust and made of high-quality ASA plastic, providing excellent durability and UV protection.

Get the AirGradient ONE

AirGradient PRO Fully Assembled

Indoor air quality monitor measuring CO2, PM1, PM2.5, PM10, TVOCs, NOX, Temperature and Humidity.

Get the AirGradient ONE

  • Model I-9PSL
  • Sensors for CO2, PM, TVOCs, NOX, Temperature and Humidity
  • 2m USB C cable (w/o power plug)
  • 12 months data platform / dashboard and API access (or connect it to your own server, e.g. home assistant)
  • Local Home Assistant support with auto discovery
  • Fully open-source code so you can easily make adjustments
  • Fully assembled
  • Tested in our test chamber with test report
  • Certified: CE, FCC, RoHS, REACH, RESET Air
  • 12 months warranty

USD 195.00

Buy Now

Also available as Kit for:
USD 138.00

Technical Data

Below is the technical data of the newest version of the AirGradient ONE. Available in our online store.

I-9PSL (AirGradient ONE, 9th Generation)
ESP32-C3-MINI (32-bit RISC-V single-core processor, up to 160MHz, 384 KB ROM, 400 KB SRAM, 8 KB SRAM in RTC, 4 MB flash in chip package)
2.4GHz IEEE 802.11 b/g/n-compliant
OLED display 1.3 inch (I2C 128x64px)
Bluetooth LE: Bluetooth 5, Bluetooth mesh
Broken out on PCB: I2C, 3 GPIO, 2 UART
11 RGB-LEDs, Push Button, Reset Button, USB C Connector
External Hardware Watchdog
Texas Instruments TPL5010
CO2 Sensor Module
SenseAir S8 (NDIR). 0 to 10000ppm. Accuracy: ±40 ppm ±3% of reading at 5 to 30°C, 0-85% RH (400 - 2000ppm range)
Particle Sensor Module
Plantower PMS5003 (laser scattering principle). Accuracy: ±10%@100~500μ g/m³, ±10μg/m³@0~100μ g/m³
Temperature and Humidity Module
Sensirion SHT40. Accuracy: Temperature ±0.2°C @ -40 to + 125°C; Humidity ±2% RH @ 0 - 100% RH
Sensirion SGP41. Accuracy: TVOC <±15 @ 0 to 500 VOC Index; NOX <±50 @ 0 - 500 NOX Index
ASA Plastic, UV Resistant and Weather Proof
2m USB C Cable including Data Lines for Flashing
Power Plug (not included)

2A 5V USB A Power Plug is Required

Dimensions & Weight
130 x 130 x 35mm, 350 grams

Winner Most Accurate Multi-Pollutant Sensor

The AirGradient ONE received two Awards at the AIRLAB Microsensors Challenge 2023.

The Microsensors Challenge is a global competition that aims to provide a robust and independent evaluation of microsensor technologies for air quality monitoring. For the first time, the challenge included testing in both France and Thailand to better understand the impact of different weather conditions, pollution levels, and sources on microsensors' performance.

The AirGradient ONE Indoor Air Quality Monitor received the following two Awards:
- Most Accurate Multi-Pollutant Indoor Air Quality Monitoring under €500.
- Best Accuracy for PM 2.5 Sensors indoors under €500.

The Jury’s Opinion:
“The AirGradient ONE is a well performing, low-cost multi-pollutant solution for indoor applications. It provides very good to excellent CO2 measurements and good PM measurements. It is an overall well balanced solution and the best multi-pollutant indoor sensor for under €500."

AirGradient ONE Microsensors challenge results
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Ideally combined with an Outdoor Monitor

We recommend that you also monitor the air quality outdoors to fully understand the air quality of your environment. By monitoring both indoor and outdoor air quality, you get valuable additional data, e.g., where the pollution is coming from, how well your home’s ventilation and air purification systems work, etc. The AirGradient dashboard is well suited to comparing indoor and outdoor air quality in combined reports and charts.

Go to our outdoor air quality monitor page to learn more about our open-source outdoor monitor.

In 2019, 99% of the world population was living in places where the WHO air quality guidelines levels were not met. Ambient (outdoor air pollution) in both cities and rural areas was estimated to cause 4.2 million premature deaths worldwide in 2016.

World Health Organisation

Open Hardware - Easy to Extend

AirGradient PCB Features

The monitor’s open-hardware / open-source nature allows easy changes and additions to the firmware and hardware. The board is powered by an ESP32-C3 mini microcontroller, which is easy to program with a wide ecosystem and has integrated WiFi and Bluetooth capabilities.

The C3 can be directly flashed through the USB C port, making changes in the open-source firmware easy.

For those who would like to adjust the monitor, breakout pins are available for I2C and additional IOs. The board provides both 5 and 3.3 volts.

We integrated an external hardware watchdog chip that automatically reboots the unit in case something goes wrong, enabling the monitor to achieve high uptime.


We are very thankful for the overwhelming support we get for the AirGradient air quality monitors and are especially thankful for people that write about their experiences using the monitors. Below is a wide range of reviews from AirGradient users!

Open Hardware, Open Source, Open Data

We at AirGradient have a strong desire democratizing air quality monitoring. Access to the information about the air you breathe should not be a privilege for the rich. Air pollution is one of the largest global environmental and health risks, requiring a high-density sensor network to understand and solve the problem. We provide a blueprint of a robust, affordable, open design that citizens and NGOs worldwide can use to measure air quality accurately.

Fully Open Source

All code, schematics, 3D files etc. are open-source and published under CC-BY-SA 4.0 license. You can easily adapt the hardware and flash your own firmware.

You own your Data

There is a trend in our industry to monetize air quality data to the extent that often the owner of the monitor does not own the data. We believe this is wrong. The data that your monitor generates should belong to the owner of the monitor.


We have partnered with openAQ, a non-profit that provides air quality data to influence policy and enables the public to access information on air pollution through open data and open-source tools.

1% for the Planet

We joined 1% For The Planet and pledged to donate at least one per cent of your annual sales to non-profit organisations dedicated to protecting the planet. You can read more about our motivation to join 1% for the Planet on our blog post ‘Why We Joined 1% For The Planet’

AirGradient provides 2000 Air Quality Monitors to UK Schools

AirGradient has been selected to provide air quality monitors for the biggest study of air quality in schools worldwide (the SAMHE Project). The objective is to understand classroom air in UK schools post-COVID, building an unparalleled data set of air quality in classrooms across the country and improve long-term air quality for all schools.


We are fortunate to have such a strong community sharing our mission to bring open, accurate and affordable air quality monitoring to everyone running thousands of open-hardware monitors in more than 70 countries around the world.

World Map with Customer Locations

Activities and Stories From and About our Community

We are blessed to have such an active community. Read more about community engagement.

The AirGradient Manifesto

This manifesto reflects our core values and the principles we stand for:

Positive Disruptor

We must be bold. We always follow our convictions and call out the issues that matter, sharing our views on topics surrounding air quality and environmental responsibility. We will not compromise for profit. We believe that open, informed, and candid discussions are the catalysts for meaningful change. We will lead by example and become a driving force for environmental monitoring.

Responsible Products

We will deliver benefits for both people and the planet. This is why we prioritise creating high-quality air quality monitors with designs that enable easy repairs and recycling, thereby extending the product’s lifespan and reducing its environmental footprint.

Open Science and Research

Our research is driven by a commitment to environmental protection, not by profits. This is why we don’t patent our air quality monitor designs but on the contrary, share them openly, allowing everyone to build them and to contribute to positive change. We do not lock users into proprietary eco-systems and we encourage sharing of air quality data and algorithms as a public good.

Community Building

We want to raise awareness about air pollution through active community building with a strong focus on informing about the dangers of air pollution. We actively support environmental justice organisations and educational institutions in their missions to provide healthier environments for everyone.

Profit Follows Impact

To deliver positive impacts on the communities, and the environment, we must sustain our business model. However we will not prioritise profits above our convictions. We embed this rationale into our everyday decision-making processes throughout all layers of our company. (e.g. by joining 1% for the Planet).

Transparency and Accessibility

AirGradient is built on a foundation of openness and inclusivity. We aim to make our products and services available to a wide range of users with a special focus on underrepresented communities. We strive to work with all organisations that want to make a positive contribution independent of their financial means.

Why we care about Air Quality

AirGradient started as a volunteer project to help a school in Northern Thailand monitor the air quality in classrooms during the highly polluted burning season. From the beginning, we have worked with students and educators to building hardware to increase awareness in the area of air quality, to understand the health impacts of pollutants, and to empower the positive changes that can be made to reduce air pollution.

The experience and expertise that we gained designing and manufacturing our professional AirGradient ONE RESET Air Accredited Monitor has been put into our open-source / open-hardware air quality build instructions and kits.

The industry-grade sensor modules used in our open hardware monitors are the same modules found in pre-built monitors costing hundreds of dollars. As a result, you get highly accurate data quality, essential to having a reliable understanding of the air around you.

We’ve pledged 1% of sales to the preservation and restoration of the natural environment.