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1. How do I choose a sensor?

The South Coast Air Quality Management District in California thoroughly evaluates air sensors available for purchase through their Sensor Performance Evaluation Center (AQ-SPEC). AQ-SPEC compares air sensors to regulatory monitors both in a laboratory test chamber and in the field on a long term basis. This is the most comprehensive air sensor testing program that we know of and we use it to select sensors for our own evaluation.

If you’re looking for more of a DIY solution, the World Air Quality Index project reviews sensors that require some hands-on experience.

2. I have an air sensor, now what?

It’s not always clear what your air sensors data means, especially if you’re trying to compare them to the air quality data found on our website.

Air sensors give readings every minute, or even instantaneously; our regulatory monitoring is reported hourly or daily. We use these longer time scales because there is a proven link between daily air quality levels and health effects. The Air Quality Index (AQI) is based on daily values. There currently is no equivalent for air sensors.

However, the EPA has launched a new tool to make instantaneous outdoor air quality data useful for the public. Their new “sensor scale” is designed to be used with air quality sensors that provide data in short time increments – often as little as one minute. EPA developed the scale to help people understand the one-minute data the sensors provide and how to use sensor data as an additional tool for planning outdoor activities.

Check out EPA’s Air Sensor Toolbox for more info.

3. How can I check if my sensor is working properly?

The easiest and most reliable way is to compare your air sensor to your nearest regulatory monitoring site. If your data isn’t matching up there could be a number of reasons why, including: your air sensor is not working properly or isn’t in a good location for sampling.