Choosing the Right Air Sensor for Citizen Science Air Quality Monitoring

Air pollution is a growing worldwide problem, yet 73% of national governments aren’t sharing air quality data with their nations. Despite the goodwill of many, collecting reliable data remains challenging due to high costs and the uneven distribution of air quality monitoring stations.

That’s why citizen scientists play an important role in collecting data and raising awareness about air quality. They are a group of regular people, volunteers, and activists who wish to spread awareness about air quality in their community.

In this article, we’ll talk about air quality monitors as primary tools for citizen science air quality monitoring and how to choose an appropriate device for your research.

Regulatory-grade air quality monitoring stations are highly accurate but can cost up to $50,000. In contrast, affordable air quality sensors often lack precision and may require frequent calibration for reliable long-term measurements—something that can be too complex for non-technical users.

However, there are low-cost sensors that perform well for citizen science air quality projects with good precision and accuracy. These devices can detect and track various pollutants in the air, such as particulate matter (PM1, PM2.5, PM10), volatile organic compounds (VOCs), nitrogen dioxide (NO2), carbon dioxide (CO2), and formaldehyde. 

Some sensors can measure humidity, temperature, and atmospheric pressure. These are not considered pollutants but can affect air quality because they affect how pollutants behave and how sensors work. 

There are two main types of sensors you can choose for citizen science air pollution​ monitoring projects - portable and stationary devices. 

Portable sensors are particularly useful for citizen scientists, activists, and community organizations who wish to capture localized pollution hotspots and personal exposure levels. They can be carried around and cover multiple locations. Another benefit is that they usually cost less compared to high-end stationary sensors. 

Stationary sensors are used more by government agencies, universities, and research institutions to monitor air pollution in a specific area. Because they’re fixed in one location, they provide consistent, long-term data that can be used for trend analysis.

Mobile air sensors address key challenges in air quality monitoring:

1. Spatial Coverage - Unlike traditional monitoring stations, mobile air sensors let you measure air quality wherever you go. Pollution levels can vary a lot, even within the same street—what you breathe in a park, near a factory, or on a busy street can be very different.
2. Personal Exposure Tracking -  Measuring air pollution where you actually spend your time is key to understanding your real exposure.
3. Community Engagement - A portable air sensor makes it easy for anyone to get involved in air quality monitoring. People and communities can collect and share data, helping to map pollution levels in different areas.
4. Affordability and Accessibility - Portable air quality monitors offer a budget-friendly way to measure pollution, unlike government-grade monitors which can cost tens of thousands of dollars.
5. User-Friendly Tools - Mobile air sensors are small, simple to use, and designed to be used by anyone—even without technical experience. Many connect to smartphone apps and cloud platforms, making it easy to track, share, and understand air quality data in real-time.
6. Data Availability and Access - By using mobile air sensors, community scientists can access air pollution data anytime on their own. 

For air quality citizen science projects, choosing the right air sensor is essential for collecting accurate, reliable, and actionable data. With growing interest in citizen science air pollution research, having a sensor that meets scientific standards while remaining user-friendly is crucial.

Here’s what to consider when choosing an air quality monitor for your citizen science project:

1. Pollutants Measured:

Depending on your research goals, you will choose a device that measures the desired pollutants. The most common parameters measured by mobile air devices are: 

• Particulate Matter (PM1, PM2.5, PM10)
• Volatile Organic Compounds (VOCs)
• Carbon Dioxide (CO2)
• Carbon Monoxide (CO)
• Black Carbon
• Nitrogen Dioxide (NO2)
• Sulfur Dioxide (SO2)
• Environmental factors such as temperature and humidity.

2. Accuracy:

When choosing an air quality monitor, accuracy is one of the most important factors to consider. Sensor accuracy = Low bias + high precision.

Bias refers to the tendency of some sensors to overestimate or underestimate pollutant levels due to environmental conditions or sensor limitations. You can check for bias by comparing your device with readings from a reference-grade monitor. Or if that’s not possible, place two or more sensors side by side and compare the results.

Precision means that the sensor provides consistent measurements under the same conditions.

Independent lab reports from organizations like AQ-SPEC (Air Quality Sensor Performance Evaluation Center) at South Coast AQMD provide objective performance evaluations, including the effects of temperature, humidity, and the presence of other gases on precision and bias.

3. Data transmission & storage: 

How an air quality sensor stores and transmits data can make a significant difference when choosing a portable air monitor for your project. 

Sensors can store and share data via:

• Wi-Fi & Bluetooth - Ideal for real-time data access through a smartphone or cloud platform. However, they require proximity to a network or phone to function.
• Cellular (4G/5G) – Enables remote data transmission, making it useful for long-term outdoor monitoring, but may require a SIM card and a data plan.
• LoRa (Long Range) – A low-power, long-distance communication method useful for community sensor networks, allowing data sharing without Wi-Fi or cellular.
• Onboard Memory and/or SD card – Stores data directly on the device or memory card, making it useful for remote locations or areas with no connectivity, with the option to download data later.

4. Data access & handling:

Depending on the device you choose, the most common options for data access and management are:

• Cloud Storage: This option allows users to access their data remotely and in real-time, but some devices may require a paid subscription for long-term data storage or historical data access.
• API Availability - If a sensor provides open API access, it will allow you to integrate air quality data into custom applications, research platforms, or data analysis tools.
• Offline Data Access (Onboard Memory & SD Card) – Some sensors allow local data storage for areas with no Wi-Fi or cellular access, ensuring data can be retrieved later.
• CSV/Manual Data Export – Certain devices offer CSV downloads via USB or Bluetooth, useful for manual data analysis in spreadsheets like Excel.
• Mobile App Integration – Many sensors come with companion apps for real-time monitoring, but check whether data can be exported or if it's locked within the app.
• ‍Privacy Concerns – Consider whether the device shares data with third parties. Make sure your data is not being used for research or commercial purposes without your consent.

• Data Ownership – Some sensors store data exclusively on the manufacturer’s servers, restricting how users can download or export their data. Ensure that you have full ownership and access to your collected data without restrictions.

Since not all sensor manufacturers grant data ownership to their customers, this has become a serious concern for the research community. In 2024, air quality experts and advocates issued an open letter supporting air quality sensing equipment that grants data ownership to the purchaser and allows for unrestricted public data sharing.

Important: If a citizen science project takes place in remote areas with no network coverage, it’s better to opt for air quality monitors that don’t require Wi-Fi to operate and have internal memory.

5. Battery life & power source:

Most sensors are powered by either replaceable batteries, rechargeable battery-operated, or solar-powered, each with its advantages and limitations. 

For the majority of citizen science projects, rechargeable battery-operated monitors are the most convenient option. However, it’s important to check the battery lifetime potential before choosing a monitor. Some devices last only a few hours, while others can run for days on a single charge.

6. Ease of use & display:

Air quality devices for community scientific projects should be intuitive and easy to use. What does this mean in practice? 

The device should have simple controls that allow users to start measuring air quality with minimal setup. A device that connects seamlessly to a smartphone app via Bluetooth or Wi-Fi ensures quick access to real-time data. The display should be clear and easy to interpret, whether it’s a built-in screen or an LED indicator system showing air quality levels in simple color codes. If the monitor relies on an app, the interface should present real-time pollution data, trends, and alerts in a visually accessible format at a fast refresh rate.

7. Need for calibration:

Regular calibration ensures the sensor remains accurate over time. Some sensors come pre-calibrated, while others require periodic calibration against reference instruments to maintain their accuracy.

The Atmotube PRO portable air quality monitor is widely used by community scientists and in research projects thanks to its technical features:

Portable and Lightweight - It weighs 3.7 ounces (104 grams) and is easy to carry. Its compact size is ideal for mobile data collection across various locations. 

No Wi-Fi Required - The device features onboard memory capable of storing up to 10 days of data, meaning it logs data even without an internet connection. This ensures uninterrupted data collection in areas without Wi-Fi access. 

Long Battery Life - It has a 2000 mAh rechargeable battery. The device can last up to 10 days of continuous monitoring on a single charge, depending on pollutants measurement frequency. This is convenient for uninterrupted extended field research measuring. 

Comprehensive Pollutant Detection - The air tester measures particulate matter (PM1, PM2.5, PM10), total volatile organic compounds (TVOC), temperature, humidity, and barometric pressure. 

Data Sharing & Accessibility:

1. With the data downloader tool, users can easily export their collected air quality data in CSV format, making it simple to analyze trends or share findings for research and advocacy.
2. The free API allows seamless integration with other citizen science projects and custom applications, helping communities collaborate, compare data, and contribute to a larger understanding of air pollution.

Citizen science air quality monitoring is a powerful tool for understanding pollution at a local level, especially where official data is limited or unavailable. By using mobile air sensors, individuals and communities can track pollution trends, identify high-exposure areas, and contribute to a broader understanding of air quality. However, the reliability of this data depends on choosing the right sensor—one that balances accuracy, ease of use, data accessibility, and portability. 

With well-informed decisions and the right tools, citizen scientists can generate meaningful data, engage their communities, and support efforts to improve air quality for everyone.