Amazon’s new Smart Air Quality Monitor

The new air monitor (on the right) really needs an Echo Show unit to display its readings on.

I’ve been interested in air quality issues for two reasons and so was attracted to this device.

The first is due to forest fires – like other western states, Washington has its fair share of enormous forest fires each year.  They seldom make the same headlines that the Californian ones do, because we tend not to build houses right next to untended forests eager to burst into flames.  But some years they cause the air quality to become seriously hazardous, even hundreds of miles away on the other side of the Cascade mountain range that divides western and eastern Washington from each other.

The other reason of course is Covid.  There is nothing inexpensive that can directly test air for whatever amount of Covid aerosol particles might be suspended in it, but as I wrote in a review a few months ago, a CO2 detector gives a good “proxy” measure of something that is readily detectable and which has some degree of correlation to Covid levels.

So it was interesting to see Amazon releasing a new “smart” device (ie connects to the internet and interacts with Alexa), an air quality monitor.  The product started shipping last week, and sells for $70.

What it Measures

The unit boasts it measures five “key factors”.  Well, yes, sort of.  The five “key” factors are :

Temperature :  It has an extraordinarily narrow range of temperature measurements, which Amazon unhelpfully expresses on its product page only in Celsius.  This is between 15° and 30° C; which is a snobbish way of saying between 59° and 95° F.  Within that range, it claims to be accurate to within 1°C/1.8°F.  Happily, it reports temperature in Fahrenheit on your phone and Echo Show units (assuming you have your default units set to that).

I bravely put on extra layers of clothing, and allowed the temperature to drop to 56° overnight, to see what would happen.  It continued to report temperatures down to 56°, at which point morning came and I decided the experiment had served its purpose and turned the heaters back on.  I guess what Amazon is actually saying is that it is accurate within the stated range, but becomes less accurate outside that range, which is unfortunate.  Sure, we try and keep our temperatures indoors nowhere near either the upper or lower limit, but if we wished to have one of these devices in a garage or shed where there’s not the same temperature controls, many of us live in areas where the temperature goes massively below 56° in the winter and occasionally breaks through to the high side of 100° in the summer.

Humidity :  This has a better, but still surprisingly narrow range, from 30% to 70% relative humidity.  Amazon says it is accurate within 10% at 25°C (77°F), so presumably the accuracy gets worse the further away from that target temperature the unit is.

Again, while we try and keep our inside environment within that range, some of us live in desert areas where the humidity can get down to 10% or less, and some of us live in the south where the humidity goes way above 70%.  This is again a disappointing range.

Carbon Monoxide (CO) :  This reads from zero parts per million up to 70 parts per million (ppm), with an accuracy of either +/- 30% or +/- 5 ppm, whichever is the larger.  Currently, my unit is reading 3 ppm, which means it could be anywhere from 0 to 8 ppm – quite a wide range.

Homes typically have between 0.5 and 5 ppm, and more if they have gas appliances.  So with 3 being almost exactly a middle reading in normal circumstances, its accuracy is from a low of “all the way down” to a high that is almost three times the number displayed.  In other words, at those levels, the value displayed is close to meaningless.

It is not surprising that Amazon is at pains to point out that the unit is not intended to act as a formal CO monitor.  Formal CO monitors typically express an initial concern at a 50 ppm level.  So this unit could get all the way to 65 ppm in reality, while registering under the 50ppm point.  CO concentrations start to become impactful at around the 70 ppm level, depending on the health of each individual.  Just at the point it is becoming important to know the CO level, this meter stops providing data.

This does beg the question – why didn’t Amazon upgrade the CO sensor to work as well as the sensor does in standalone CO units?  This seems like a very disappointing limitation, artificially imposed for no reason other than the obvious one – cost control.

Particulate Matter (PM2.5) :  The unit is rated to sample levels between 0 – 500 ug (micrograms) per cubic meter of this type of pollution.  Amazon rates its unit as being accurate to within either +/- 20 ug/cu m or 20%, whichever is the greater.

Normal levels range from close to zero and up to 12.  Over 35 starts to be significant, and over 50 starts to be of concern.  So again, the +/- 20 ug/cu m accuracy of the unit greatly detracts from the meaningful nature of the information it displays.  At 35 units of concentration, the accuracy is +/- 57%.

My unit has registered as high as a 333 count – this was when I forgot I had a frying pan heating up in the kitchen, and come back to discover a lot of smoke in the air.  Ooops.

There are three categorizations of particulate matter – coarse particles, designated PM10, fine (PM2.5 – the particles measured by this meter) and ultrafine (PM0.1).  The numbers are the diameter of the particles in micrometers (um).  The PM10 designation is actually “all particles of sizes less than 10 uM”, so it includes the PM2.5 and PM0.1 counts.  Similarly, the PM2.5 measure includes the PM0.1 (but not the PM10) count (although the measurement device may not be sensitive enough to include the smallest sizes).

PM2.5 particular often come from wild fires, and also other types of fires/burning, including power plant and vehicle emissions.  Aerosolized Covid particles range in size, both smaller and larger than 2.5 um, with the largest aerosol particles ranging up to 5 um.  Larger than that is considered to be a respiratory droplet, which doesn’t hang in the air so long.  This article explains a lot more about particulate matter.

In an answered question on the Amazon site, Amazon says this unit measures particles ranging between 0.3 and 2.5 um.

Volatile Organic Compounds (VOC) :   It is rated as having an accuracy of either +/- 10% or +/- 10 points, whichever is the larger, and a range of from 0 – 500 points.

The term “point” is puzzling.  On their site, Amazon answered a question to say that the VOC rating is “a relative index not an absolute measurement”.  This makes the measurement utterly meaningless and extremely regrettable, because it makes the composite air quality score also meaningless.

Amazon describes VOCs as comprising things such as paints, cleaning supplies, pesticides, building materials and furnishings, and cosmetic products.  Empirically it also seems to detect sprayed silicone lubricant, and cooking odors (and, ahem, cooking-related smoke!).  Other examples include aerosols, fuels, solvents, deodorizers, mothballs, and in general, just about anything that “gases off” (in most cases, “has an odor”) and which is not water soluble.

The other puzzling thing about the VOC measurement (apart from “everything”!) is that Amazon implies their scale ranges from 0 to 500.  But I’ve several times had a reading soar all the way up to 100, very quickly, but it stops at 100, which seems to also be maximum on the display scale.  I’m certain in some cases, and judging by the speed of the run up to 100, that the measured value goes beyond 100, but this is never shown.  That’s a strange limitation and not a good one.

There are no federal standards for VOC levels per se – perhaps because different types of VOCs can cause wildly differing degrees of harm at greatly different concentrations, although there are guidelines for various specific types of VOC emissions.

Air Quality Score :  Amazon derives a composite Air Quality Score from these five measures.  There is no information provided as to how this score is calculated, or what weightings are given to what factors.  It also has no known correlation to other measures such as “Air Quality Index”.

The Air Quality Index (AQI) score is an officially defined rating.  It doesn’t include consideration of three of the five items measured by this unit (temperature, humidity, and VOCs) but does include carbon monoxide and particulate matter counts, as well as also ozone, sulfur dioxide, and nitrogen dioxide.  The AQI is given as a number on a scale from 0 – 500 – lower numbers are better than higher numbers.

Amazon’s Air Quality Score is a meaningless number that can’t really be compared to other scores on other scales, and which also has little relation to the quality/safety of the air we breathe (for example, the air quality score plunged when the temperature dropped on my low temperature test).  A cold room might be uncomfortable, but that’s not the same as saying that the air quality is low because the temperature is cold.

Air Quality Factors Not Measured

As mentioned immediately above, not only are two of the five measurements laughably trivial in nature (temperature and humidity) and a third meaningless (VOC), but there are many relevant components of a “real” air quality index the unit doesn’t test.  The first three items on this list are part of an official AQI rating.  The others are just things on a “wish list” of “would be nice to know” things, which the unit also doesn’t measure.

      • Ozone
      • Sulfur Dioxide
      • Nitrogen Dioxide
      • PM10 and/or PM1.0 and/or PM0.1
      • Carbon Dioxide
      • Natural gas (ie methane)
      • Radon
      • Mold spores (but possible correlation with PM2.5 and VOC)
      • Asbestos (other than inferred through PM2.5)

Installing and Using the Indoor Air Quality Monitor

As you can see from the picture at the top of the article, the unit is a small white box, with a grill and light on the front of it, measuring about 2.5″ x 2.5″ x 1.5″.  It gets power from a “wall wart” type plug in power supply (included), that feeds a 5V power line to the unit, with an old-fashioned micro-USB connector.  You can simply place it on any surface that makes sense.

When you turn it on for the first time, it says it takes up to two days to calibrate.  That’s a very puzzling concept – how can it self-calibrate?  Usually any calibration involves comparing a known value with the device’s measurement over a range of values and then correcting the device’s readings, but there is no way this could be done.

But, whatever “self-calibration” means, it starts to display values within an hour or so, and they don’t seem to massively change after the self calibration has been complete.  The unit is guaranteed to meet its performance specs for three years, but how will you know if it drifts out of specification?

It is stated as being for indoor use only.  That’s probably because it isn’t rain proof, and also because its delicate sensors might not withstand the larger swings in values outside, and might even be upset by strong winds.

Inside the unit are of course the sensors, plus also a very low powered fan that ensures there is an air flow passing through the unit for the sensors to sample.  It makes no perceptible noise, except for a brief burst when you first plug it in and it self-cleans.

The grill on the front is the air intake.  Above it is a single color-changing LED.  Green means good air, orange means not so good, and red means bad.  I’ve seen it all three colors from time to time.

If you want to know more than the color itself, you’ll need to ask a regular Echo unit or your Alexa app.  The monitor has neither a microphone nor a speaker, so can’t be directly spoken to and won’t directly reply.  (It also doesn’t have a camera.)

Apart from a brief listing of commands that flashed by in the Alexa app while setting up, there is no listing of commands provided, particularly in the tiny little help booklet.  Really, this is unacceptable.  What is the point of releasing a device that is all about connecting with and being controlled by Alexa, but not then making it easy for people to know how to do so?

It seems there is one main command – Alexa, what’s the indoor air quality.  This could be modified by adding the name/location of the unit if you have more than one of them – and Amazon without a hint of embarrassment suggests with a straight face we should add them to most/all of our rooms.

You can also ask about the indoor temperature or humidity or “VOC” (say the letters one by one).  I’ve not worked out how to get it to tell me the PM2.5 count.

Asking a non-screened regular Echo unit “What is the indoor air quality” just gets a good/bad type response – no more helpful than the light on the front of the unit.  If you ask the question of an Echo Show unit, you’ll get a more helpful display on its screen showing all five attributes and their present value, plus an option to see changes over the past hour, day, or week.  Echo Show 5 units can often be purchased for about $50 on Amazon, and this is one case where they are clearly helpful.

The unit displays a series of five horizontal lines on an Echo Show (see the picture at the top of the article) – one for each parameter – with the lines divided into three sections – green, orange, and red, for good/poor/bad readings.  There is a small dot to show the current value and the value is displayed at the end of the line.

But the interface is counter-intuitive, particularly for temperature.  I allowed the house to drop to 56° because I was curious to see what would happen when the temperature dropped below the unit’s operating range.  The temperature line went red, and the dot went far to the right of the scale.  Normally you’d expect low values on the left of the scale, as is the case for the CO, VOC and PM2.5 readings (but not humidity).

In reality, both temperature and humidity have both a “bad low” and a “bad high” set of values.  So they should have a red part of the scale at the left and right, then orange, then green in the middle.  Instead, the indicator variously travels to the left or right, not indicating the value, but the correspondence of the value to “good” or “bad”.

The sensors apparently update every ten seconds, but there’s no way you can get an ongoing realtime display of what is happening.  The Echo Show units automatically close the display down and go back to their home screen after only a few seconds of showing the current values.

Looking at the wild swings in my indoor air quality, you might wonder what sort of environment I live in. The unit seems to massively exaggerate occasional blips in quality, particularly on the daily summaries.

You can also ask the Show unit to display values per day (counter-intuitively the “week” option), per hour (yes, the “day” option) and every five minutes (which is therefore the “hour” option).  I was astonished to see how I managed to score zero on one day of this displayed set of daily values (which surprisingly appears as an orange rather than red bar).  It seems  the unit is reporting on “worst value each day” rather than “average” (or even “best”) values.  This could be (and should be!) easily changed, in the software, perhaps to show you a bar with a high, low, and average point for each day which would be much more meaningful.

Other than the light on the front of the unit, it won’t proactively tell you anything, although you can set up routines for the unit to tell you if the temperature goes above or below specified values. So, for many of us, after plugging it in and turning it on, much of the time we’ll forget all about it.

It seems, from the screen shot above, that the monitor is quite active and busy reporting significant swings in air quality on a regular basis.  That’s not altogether the case.  Over the ten days I’ve been using my unit, the temperature, humidity, and carbon monoxide readings have changed very little.  The PM2.5 count went quite high one time due to an, ahem, “kitchen mishap”, and the VOC number is very sensitive – I sprayed a bit of silicon lubricant on an item downstairs, and that pushed the monitor up to “max” on its VOC, upstairs, within a couple of minutes.

Every time I cook, whether burning things or not, the VOC and/or PM2.5 numbers go very high.

Rushed to Market, Incomplete?

This is the third Amazon/Alexa device in a row I’ve reviewed that feels as if it has been rushed to market before all the software and capabilities have been enabled.

The first was the Smart Thermostat – it won’t remotely activate the fan only setting, it can’t be turned off remotely, you can’t ask it about its humidity reading, and it has an artificially constrained range of temperatures that can be set, to name just a few of its current limitations.

The second was the Echo Show 15 – a very limited number of widgets, many of which are poorly implemented, and a massive lack of “smart home” data that can be displayed (including both the Smart Thermostat and now the Indoor Air Quality Monitor).

And now, this unit too.  There’s a very narrow range of Alexa commands, and unlike other units, it won’t accept synonyms or other forms of the command.  Plus you can only build routines in response to the temperature measurement – the least likely of the measurements that you’re likely to want to build routines for.  It would be very useful to have it sound an alert if the PM2.5 level went above a trigger point, because that indicates a possible abundance of smoke, ie from burning food on the stove or a fire in general.  It could be helpful for this to be able to “talk” to an Amazon Smart Thermostat so the two units can come to a consensus on some basis as to if heating, cooling, or air circulation is needed.

There’s no clear reason why these types of functions couldn’t be enabled, other than the device being rushed out in time for Christmas shopping, prior to all the software having been completed.

Three disappointments in a row.  What would Jeff Bezos say, if he were still at the helm?

I remain hopeful that all three devices may improve over time.  But when?


Amazon’s Smart Air Quality Monitor is priced at $69.98.  It claims to measure five “key factors” of your air quality.  In reality, few people would expect temperature and humidity to be included among the five key factors – you’re only being given (sold!) data on three additional factors (carbon monoxide, medium sized PM2.5 particular matter, and some unknown estimation of some volatile organic compounds).

Plenty of other units report on more air quality factors, or on specific factors such as radon and a more exact carbon monoxide measure and also provide automatic warnings.

We’re left with the feeling that the Amazon unit is as much a gimmick as it is a “serious” unit, although hopefully its range of available actions in response to changes in the attributes it is measuring will grow.

As a $70 gimmick, it is sort of fun to have, and it will be interesting to see how it responds to next season’s forest fires and the air pollution from that.  It would be interesting to then see if an indoor air filtration unit impacts on the PM2.5 and VOC readings or not – hopefully yes for PM2.5, probably not for VOC.  But, until then, let’s just say that the unit is not changing my life in any meaningful way.

But it is perhaps a good gift for the gadget lovers in your life.

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