## Choosing Sensors Often the first step is to look for a sensor for what you're hoping to measure. In the community posts below, we're collecting info on different kinds of air quality sensors, and their: * cost * sensitivity/accuracy * links and documentation Can you afford a sensor? Can it detect what you're looking for? Where can you learn more about it? ### Posts about choosing and evaluating an air sensor [notes:grid:air-sensor-eval] ### Expected ranges and useful detection limits for pollutants of interest This [table](https://www.epa.gov/sites/production/files/2016-06/documents/air_sensors_webinar_slides_06-29-16.pdf) from an EPA [Air Quality Monitoring and Community Science webinar](https://www.epa.gov/sites/production/files/2016-06/documents/air_sensors_webinar_slides_06-29-16.pdf) lists the six criteria air pollutants and a couple additional pollutants, with background levels you might see in the environment in the “Range to Expect” column and useful detection limits for sensors. **** ## Wikis about air sensors [wikis:air-sensors] ## Air sensor projects Public Lab pages and posts tagged `air-sensor-projects` will appear here [nodes:air-sensor-projects] ## Questions [questions:air-sensors] ## Further reading and resources + Environmental consultant Tim Dye’s “[4 questions to ask before buying an air quality sensor](http://tdenviro.com/wp-content/uploads/2017/09/4-questions-when-buying-air-sensors.pdf)” neatly summarizes what to consider when choosing an air sensor. + [Snuffle.org](http://www.snuffle.org/): lots of information on low-cost sensors for various air pollutants. + [Air Quality Sensor Performance Evaluation Center (AQ-SPEC)](http://www.aqmd.gov/aq-spec/evaluations): from the South Coast Air Quality Management District, this program tests and evaluates air sensors “in the field, under ambient conditions, and in the laboratory under controlled environmental conditions.” + [Air Sensor Toolbox](https://www.epa.gov/air-sensor-toolbox): from the US Environmental Protection Agency, this toolbox includes guidance on how to use air sensors and their data, plus information on sensor performance and evaluation results. ...
| Author | Comment | Last activity | Moderation | ||
|---|---|---|---|---|---|
| cfastie | "A 1/4" stereo/phone plug connects to the HCHO sensor and two wires from that cable connect to the Arduino (tip of plug to A3, ring to GND). Below (..." | Read more » | over 6 years ago | |||
| zengirl2 | "@liz I can meet with @nshapiro with some Arduinos, but I think my question is where do you attach alligator clips or wires for testing this beast? " | Read more » | over 6 years ago | |||
| liz | "Perhaps @Zengirl2 can go over the Nick's house and bring an Arduino? (They are both in Philly) and for good measure we can open up a video link wit..." | Read more » | over 6 years ago | |||
| cfastie | "The first step might be to arrange for the co-location of the HCHO sensor, an Arduino, and somebody casually familiar with Arduino. Has the proper ..." | Read more » | over 6 years ago | |||
| liz | "Hi @cfastie -- thank you so much for asking these questions. Here's what i know -- Nick has to go to Georgia with a working solution in 2 weeks...." | Read more » | over 6 years ago | |||
| cfastie | "Kina, Thanks for the great information. Liz, It might help to know more about this project. What is the time frame for deployment? What has been tr..." | Read more » | over 6 years ago | |||
| liz | "Please give me a call at +1 336-269-1539 " | Read more » | over 6 years ago | |||
| liz | "OK awesome @kinasmith and @cfastie ! What would be helpful for me to do as a facilitator to help Nick get all the way there? Here's some ideas: 1) ..." | Read more » | over 6 years ago | |||
| kinasmith | "this is actually an excellent solution to this problem without adding additional parts/complexity. The 1.1v internal reference is much more stable ..." | Read more » | over 6 years ago | |||
| kinasmith | "I'll just chime in here for a second as someone who has worked a lot with arduino dataloggers and ADC's, etc. I agree with @cfastie on all points...." | Read more » | over 6 years ago | |||
| Bronwen | "Apologies for the mass tagging here, I know a lot of you have been in the mix providing great support and advice so far, but if anyone feels they h..." | Read more » | over 6 years ago | |||
| cfastie | "There is a very simple way to read the HCHO sensor with a resolution of about 10 ppb, assuming the range of the sensor is 0 to 1000ppb. (Out of the..." | Read more » | over 6 years ago | |||
| Alastair_ | "8-Bit resolution is fine i'd think, you just need to amplify the signal. Any first year electrical engineering student worth her salt can design th..." | Read more » | over 6 years ago | |||
| warren | "I'd like to try to get input from some of the many people at http://publiclab.org/contributors/datalogger who have almost certainly interfaced thei..." | Read more » | over 6 years ago | |||
| nshapiro | "Thanks so much, Chris! So it does look like the relationship is linear between output and ppb. here is what a friend writes who has used this tool ..." | Read more » | over 6 years ago | |||
| zengirl2 | "Unfortunately this is out of my league. You might try posting on Adafruit's forum asking about signal, but they won't be able to speak for the sens..." | Read more » | over 6 years ago | |||
| cfastie | "I think it is par for the course that a random proprietary sensor will not work gracefully with an Arduino. In this case, it might be that a standa..." | Read more » | over 6 years ago | |||
| warren | "Thanks, Nick - yeah, i think the ADC stuff is more complex than it should be! Maybe we can recruit some help to get a basic Arduino sketch for thi..." | Read more » | over 6 years ago | |||
| nshapiro | "Ah okie thanks! this is all waaaaay over my head. thanks for the clarification re:professional sensor outputs. I think the precision is higher than..." | Read more » | over 6 years ago | |||
| warren | "As to your other question about professional sensors -- I think there's nothing super special about the sensor you have, and almost any system (ard..." | Read more » | over 6 years ago | |||
| warren | "Sorry, Nick I think it may still be an open question whether the manufacturer provides greater precision than this. Do you know? And I think the p..." | Read more » | over 6 years ago | |||
| nshapiro | "Thank you, Chris! This is extremely helpful, although a bit disappointing that none of the DIY data loggers would work without serious fiddling or ..." | Read more » | over 6 years ago | |||
| warren | "@nshapiro - I think this is a provisional "yes" -- thanks @cfastie! Which is to say, a good follow-up question for the company is "how much resolut..." | Read more » | over 6 years ago | |||
| cfastie | "Any Arduino-based data logger should be able to read the signal from that sensor and save the reading at regular intervals. The main obstacle is th..." | Read more » | over 6 years ago |