Milesight Air Quality Monitors Compared: AM102 vs AM103 vs AM308

Last updated: 23 July 2026

Short answer: buy the AM102 (£47.88 ex VAT) when you only need temperature and humidity in an office, classroom or plant room. Buy the AM103 (from £127.19) when CO2 matters — it adds an NDIR CO2 sensor and an e-ink display, which is exactly what HSE ventilation checks and classroom monitoring call for. Buy the AM307 or AM308 (from £224.45) when you need the full picture: TVOC, barometric pressure, light and motion, with the AM308 adding PM2.5 and PM10 particulates for dust and wellbeing programmes.

Every Milesight air quality monitor in this family is a LoRaWAN device that runs for years on batteries and reports into any LoRaWAN network server — including the embedded server inside Milesight’s UG65 and UG67 gateways, so a small deployment needs no software subscription at all.

On this page:

• What is the difference between the AM102, AM103 and AM308?
• Milesight AM102: temperature and humidity on a budget
• Milesight AM103: the CO2 monitor for classrooms and offices
• Milesight AM307 and AM308: the full indoor air quality picture
• Which Milesight air quality monitor do you need?
• What do they cost in the UK?
• How do you deploy them?
• Frequently asked questions

What is the difference between the AM102, AM103 and AM308?

The difference is how much of the air they measure. The AM102 is a 2-in-1 sensor: temperature (-20 to +60 °C, ±0.2 °C) and humidity (0–100% RH). The AM103 is a 3-in-1 that adds NDIR CO2 sensing from 400 to 5,000 ppm. The AM307 measures seven parameters — temperature, humidity, CO2, TVOC, barometric pressure, light and motion — and the AM308 adds PM2.5 and PM10 particulate sensing on top. Every model in the family is LoRaWAN (EU868) and wall-mounts with screws or 3M tape. Choosing a Milesight air quality monitor is therefore a question of which numbers your building has to report, not which datasheet is longest.

Each model also comes in an “L” variant — AM102L (£38.90), AM103L and AM308L (£239.41) — which drops the screen. No display means a lower price and, on the AM103L, roughly a year more battery life, which is the right trade in plant rooms, voids and stores where nobody reads the wall.

Milesight AM102: temperature and humidity on a budget

The AM102 answers one question: are the conditions in this room right? At £47.88 ex VAT it is the value pick for monitoring offices, classrooms, server cupboards, archives and plant rooms where CO2 is not the concern. Accuracy is ±0.2 °C on temperature, and the e-ink face shows the current reading to anyone in the room.

If the room is damp, unheated or outdoors, step sideways rather than up: the sealed EM300-TH is the same price in an IP67 housing, and that comparison covers the temperature-only decision in detail.

Milesight AM103: the CO2 monitor for classrooms and offices

CO2 is the number UK guidance actually asks about. The HSE says CO2 levels consistently above 1,500 ppm in an occupied room indicate poor ventilation and action should be taken, and treats around 1,000 ppm as consistent with the recommended fresh-air rate of 10 litres per second per person (HSE, Using CO2 monitors). The AM103 measures exactly that, with a self-calibrating NDIR cell rated 400–5,000 ppm at ±(30 ppm + 3% of reading).

The 2.13-inch e-ink screen shows the live CO2 reading and an emoticon, so teachers and facilities staff can act — open a window, drop the occupancy — without logging into anything. Two replaceable ER14505 batteries carry it for roughly three to four and a half years. This is the model we specify for CO2 monitoring in schools and for HSE-style ventilation checks across offices.

The HSE also cautions where to put a CO2 monitor: head height, away from windows, doors and vents, and more than 50 cm from people, because exhaled breath skews the reading. A wireless wall-mounted sensor makes that placement easy in a way a plug-in desktop unit never manages.

Milesight AM307 and AM308: the full indoor air quality picture

Above the CO2 tier, the AM307 and AM308 turn one wall point into a complete indoor-environment station. Both add TVOC (volatile organic compounds from cleaning products, furnishings and finishes), barometric pressure, a light sensor and PIR motion — so the same device that scores air quality also tells you whether the room is actually occupied. A traffic-light indicator and buzzer flag poor air on the spot, and the 4.2-inch e-ink display shows the full readout.

The AM308 is the one to choose where particulates matter: it adds PM2.5 and PM10 sensing for dust from roads, renovation, workshops and print rooms. That is the difference that matters for wellbeing programmes and for any site near a busy road. Because the PM fan works harder, battery life is around 1.3 years against the AM307’s 3.9, so on both models we usually recommend the USB-C option for permanent installs.

If your interest in occupancy goes beyond a PIR flag — desk-level utilisation, people counting — pair the air quality layer with the sensors in our office air quality monitoring range or the Smart Building Occupancy Kit (£531.21), which bundles occupancy, air quality and the gateway in one box.

Which Milesight air quality monitor do you need?

Match the model to the room, not the datasheet:

• Plant rooms, stores, archives, server cupboards: AM102 — or the screen-less AM102L at £38.90, since nobody is there to read a display.
• Classrooms, meeting rooms, GP waiting rooms: AM103. CO2 is the ventilation metric UK guidance measures, the e-ink face makes the reading public, and the price steps in well under the 7-in-1 tier.
• Open-plan offices and wellbeing programmes: AM307 where particulates are not a concern, AM308 where they are. The TVOC and PM numbers are the ones tenant wellbeing reports ask for.
• Workshops, print rooms, sites near main roads: AM308. PM2.5/PM10 is the parameter the cheaper models simply do not have.

Mixed estates mix models. A typical school deployment is an AM103 in every classroom and one AM308 in the hall; a typical office is AM308 on each floor plate with AM102s in the back-of-house rooms. Everything lands in the same dashboard because it is all LoRaWAN.

What do they cost in the UK?

Current UK pricing for each Milesight air quality monitor, ex VAT, from UK stock: AM102L £38.90, AM102 £47.88, AM103 from £127.19, AM307/AM308 from £224.45, AM308L £239.41. All are buyable online with card, Klarna or Clearpay, with volume quotes priced within one working day.

For a first deployment, the LoRaWAN Starter Kit (£619.49) pairs a gateway with three environmental sensors and removes the integration guesswork — our guide to choosing IoT hardware covers how to scale from there. Full range and stock on the Milesight UK distributor page.

How do you deploy them?

Every model here needs a LoRaWAN gateway within range — typically one UG65 covers a floor or a small building, and its embedded network server means readings can go straight to a dashboard with no monthly platform fee. Our Milesight gateway buyer’s guide compares the options, and our indoor air quality monitoring guide covers thresholds, placement and what to do with the data once it flows.

The readings only earn their keep once something happens when they move. Set a dashboard alert at the HSE’s 1,500 ppm line and route it to the facilities inbox; set a second, lower warning around 1,000 ppm so staff can open a window before the room ever goes red. The AM307 and AM308 close that loop locally too — the traffic-light indicator and buzzer act on the spot, with no dashboard in the room at all.

Frequently asked questions

What is the difference between the Milesight AM103 and AM308?

The AM103 measures temperature, humidity and CO2; the AM308 adds TVOC, barometric pressure, light, PIR motion and PM2.5/PM10 particulates, plus a larger 4.2-inch display, a buzzer and a USB-C power option. The AM103 costs from £127.19 ex VAT, the AM308 from £224.45.

Does the Milesight AM103 use a real NDIR CO2 sensor?

Yes. The AM103 uses a nondispersive infrared (NDIR) cell rated 400–5,000 ppm with ±(30 ppm + 3% of reading) accuracy — the same sensing principle used in professional ventilation surveys, not an estimated “eCO2” value.

What CO2 level indicates poor ventilation?

UK HSE guidance says CO2 consistently above 1,500 ppm in an occupied room indicates poor ventilation and you should act, and treats around 1,000 ppm as consistent with 10 litres per second of fresh air per person. Continuous monitors like the AM103 capture that “consistently”, which spot checks miss.

Can these sensors run on USB power instead of batteries?

The AM307 and AM308 run on batteries or USB-C, and we recommend USB-C for permanent installs because particulate sensing shortens battery life to around 1.3 years on the AM308. The AM102 and AM103 are battery devices, with replaceable cells lasting roughly three years or more.

Do I need a gateway to use a Milesight air quality monitor?

Yes — these are LoRaWAN sensors, so readings travel to a LoRaWAN gateway such as the Milesight UG65. One gateway serves dozens of sensors across a building, and the embedded network server inside Milesight gateways means a small site needs no software subscription.

What does the “L” in AM102L, AM103L and AM308L mean?

The L variants delete the e-ink display to cut cost and extend battery life — the AM103L runs roughly a year longer than the AM103. Choose an L model for unoccupied spaces; keep the display where people in the room should see, and act on, the reading.

The bottom line

The AM102 tells you a room’s conditions, the AM103 tells you whether it is ventilated, and the AM307/AM308 tell you nearly everything else about the air. Start from the question each room has to answer, mix models across the estate, and put the display versions where the reading changes behaviour. Prices above are live UK stock — browse the Milesight sensor range, or send us the floor plan and we will spec the mix and quote it within one working day.