Is anyone using mobile air quality sensors in their setups? Advice wanted

Hi everyone!

Last yearly I briefly mentioned retrofitting the Trek Pack with air quality sensors.

Well, it turns out cheap(ish), low powered and rugged mobile air quality sensors are not as readily available as I first, naively, first thought.

It seems Pimoroni’s Enviro+ Raspberry Pi add-on is a good solution, costing less than $100 for the unit. This has been suggested to me by quite a few people that read the original blog post linked above.

A ‘dream’ device for us would capture carbon dioxide (CO2), carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO2), ozone (O3), and particulate matter (PM2.5).

I’ve bought an Enviro+ to start testing (I’m aware it does not capture all of the above) and therefore want to make sure I’m not missing other, potentially better suited, alternatives.

Thanks for your help!

I’ve been doing a little bit of research into this over the last few days. Anyone who stumbles across this post should read this linked report which covers ‘low-cost’ sensors (although any mention of prices, or even a definition of low-cost, is not mentioned anywhere in the article)

Here is what I was able to dig up from one our lead scientists. The aqmd link is quite good.

Hello Brian,

As par of the National Air Pollution Surveillance Program, we have started to explore and test these new technologies to measure air contaminants but they are not use for reporting purposes again standards or to the public.

The Aclima system used by Google is not a low cost system has they are often referred to; Aclima uses a sophisticated inlet system that switches between 3 ports depending on the speed of the vehicle to maintain isokinetic flow to the instruments. The measuring instruments are also not low cost, they use similar instruments that we use in NAPS in smaller less accurate versions.

Most low cost sensors uses a power source (not batteries), Wi-Fi or cell communication and are weather resistant (most of them cannot withstand Canadian winters).

The performance of the CO, NO, NO2, SO2 sensors are very poor ( http://www.aqmd.gov/aq-spec/evaluations/summary-gas), for this reason we have decided to use only PM sensors for which the results are much better (http://www.aqmd.gov/aq-spec/evaluations/summary-pm).

Our goal is not to get a snap shot of a city at a given time but to track air pollution over several years, for this reason fixed sites are preferred.

It seems to me that most sensors on the market (inc. those PM sensors linked in the AQMD doc) are focused on static capture (or otherwise require a more complex design to properly function). Would you agree @chelseabrian ?

I guess it depends on the objective. I see Aclima as a sort of Google Maps/Directions for air quality monitoring. Aclima does hyperlocal monitoring to the street block level. I guess they see or are developing a market for this sort of thing.

Interesting :slight_smile:

I found this project that looking really interesting : https://learn.adafruit.com/remote-iot-environmental-sensor/overview

Mapping for Change just sent out a low tech solution also, but might be useful to someone so thought I’d share: https://mappingforchange.org.uk/wp-content/uploads/2019/03/Nitrogen-Dioxide-Toolkit2019.pdf

I’ve been speaking to a few people about this in some detail this week. Here’s one response that I think sums up mobile air quality measurements:

Over the years many people have tried a mobile units using electrochemical sensors.

One of the main issues is the length of time sensors need to settle down from switch on, which can be up to 24 hours. Another issue is the R90 time (which is the time the sensor takes to get to 90% of the gas reading in a minute) thus if you are travelling 30mph how far do you travel and what is the source of the pollution.

I should note, this person has not said it’s impossible, just difficult to get consistently accurate measurements whilst on the move.

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