Apollo MSR-2 with CO2

Apollo MSR-2 with CO2

CO2, occupancy, UV, ambient light, pressure and temperature in one small USB-C sensor, built around Home Assistant rather than particulate monitoring.

Launch Year: 2024

Model: MSR-2

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Our review

Apollo MSR-2 with CO2 Review: A Compact Home Assistant Multisensor With CO2 On Board

The verdict

The Apollo MSR-2 with CO2 is less a classic air quality monitor and more a room-awareness multisensor that happens to include CO2. It combines CO2 with occupancy, ambient light, UV, atmospheric pressure and temperature, runs on USB-C over 2.4 GHz Wi-Fi, and integrates with Home Assistant. What it does not do is particulates: there is no PM2.5, PM10, TVOC or NOx sensing, and no humidity reading either. At its low price it is a strong value for automation-heavy Home Assistant setups, but it is not the device to buy if you want to track dust, smoke or pollen.

Best for
  • Home Assistant users
  • Room automation and presence
  • CO2 and ventilation tracking
  • Budget multisensor setups

Pros

  • CO2 sensing at a low price
  • Occupancy detection for presence-based automations
  • Ambient light and UV sensing, useful for daylight-driven rules
  • Atmospheric pressure and temperature included
  • Native Home Assistant integration
  • Temperature and air quality alerts, with history records
  • Simple USB-C power

Cons

  • No particulate sensing at all: no PM0.3, PM1, PM2.5 or PM10
  • No TVOC, NOx, carbon monoxide or radon sensing
  • No humidity sensor, so no humidity alerts
  • Home Assistant only: no Alexa, Google Home, HomeKit, SmartThings or Matter
  • No screen on the device
  • Wired USB-C power with no battery option
  • Indoor only, with no weather resistance rating

Who is the Apollo MSR-2 with CO2 for?

It suits someone building room-level automations in Home Assistant who wants several signals from one small device instead of scattering four sensors around. Occupancy tells the room whether anyone is there, ambient light and UV describe how much daylight is coming in, and CO2 tells you when the air has gone stale. Because it is Home Assistant only, this is a device for that ecosystem specifically, not a general-purpose monitor for an Alexa or Google Home setup.

What the MSR-2 senses

CO2 is the air quality headline: at high indoor levels it is the pollutant most associated with poor sleep and trouble concentrating, so it is the reading that tells you a closed room needs ventilating. Around it sit occupancy detection for presence-driven automations, ambient light for brightness-based rules, a UV sensor that indicates how much sun is coming through the window, atmospheric pressure, which shifts with weather changes, and temperature. Temperature and air quality alerts are both supported, and readings are recorded over time so trends stay visible.

What to know before you buy

The sensor gaps matter more than usual on this one. There is no particulate sensing at all (no PM0.3, PM1, PM2.5 or PM10), no TVOC, no NOx, no carbon monoxide and no radon, so it will not tell you about smoke, cooking particles, pollen or off-gassing from cleaners and furniture. It also has no humidity sensor, which means no humidity alerts and no mold-risk signal. On the platform side, Home Assistant is the only supported integration: Google Home, Alexa, Apple HomeKit, SmartThings, IFTTT and Matter are all unsupported. There is no screen, so every reading lives in your dashboard, and power is wired USB-C with no battery option. It carries no weather resistance rating, so keep it indoors.

Is the Apollo MSR-2 with CO2 worth it?

For the money it is one of the cheaper ways to get a real CO2 reading plus presence and light sensing into Home Assistant, and it supports the automations and history that make those readings useful. Judge it as a multisensor rather than an air quality monitor: if your goal is ventilation and room automation, it delivers; if your goal is tracking particulates or humidity, you need a different device, or this one alongside a dedicated particulate monitor.

Frequently asked questions

Does the Apollo MSR-2 measure PM2.5 or other particulates?

No. It has no particulate sensor of any size, and no TVOC or NOx sensing either. Its air quality reading is CO2.

Does the MSR-2 with CO2 work with Alexa, Google Home or HomeKit?

No. Home Assistant is the only supported platform.

Does it measure humidity?

No. It reads temperature, CO2, atmospheric pressure, ambient light, UV and occupancy, but there is no humidity sensor.

What can the occupancy sensor be used for?

It detects whether the room is occupied, which is the trigger most people use for lighting, climate and energy-saving automations in Home Assistant.

How is the Apollo MSR-2 powered?

Over USB-C. There is no battery option, and it connects over 2.4 GHz Wi-Fi.

At a glance

Summary

Everything this air quality monitor supports, grouped by category.

Power
Wired (USB-C)
Connectivity
2.4 GHz WiFi
Integrations
Home Assistant
Sensors
CO2TemperatureAtmospheric PressureAmbient LightUVOccupancy
Alerts
Temperature AlertsAir Quality Alerts
Features
History Records

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Company
Apollo Automation logo

Apollo Automation

USA flagHeadquartered in USA

Apollo Automation is a smart home maker focused on local, privacy-first sensors built around ESPHome and Home Assistant. Its lineup includes mmWave presence and motion multisensors, air quality monitors tracking CO2, VOCs, temperature and humidity, plant and leak sensors, plus hubs and accessories. Apollo emphasizes open-source software and 3D-printable, customizable hardware with onboard buzzers and RGB LEDs, and runs with no cloud and no subscription. Devices are Made for ESPHome and Works Locally with Home Assistant certified, appealing to users who want affordable, fully local automation.

Full specifications

Every spec, organized

Browse the full breakdown by category. Tap the on any row for what it means, or the for sources and documentation.

Size & Materials
Weather Resistance

NO

Dimensions

?

Weight

?

Power
Wired

USB-C

Battery Type

-

Battery Life

-

Connectivity
2.4 GHz WiFi

YES

5 GHz WiFi

NO

Ethernet

NO

Bluetooth

NO

Z-Wave

NO

Zigbee

NO

Thread Protocol

NO

Other

NO

Display
Screen

NO

Screen Type

-

Color Screen

-

Touch Screen

-

Screen Size

-

Screen Resolution

-

Integrations
Google Home

NO

Alexa

NO

Apollo ships ESPHome firmware aimed at Home Assistant and publishes no Alexa skill

Apple HomeKit

NO

Samsung SmartThings

NO

Home Assistant

YES

Matter

NO

Sensors
TVOC

NO

PM0.1

NO

PM0.3

NO

PM1

NO

PM2.5

NO

PM10

NO

CO

NO

CO2

YES

NOx

NO

Radon

NO

Temperature

YES

Humidity

NO

Atmospheric Pressure

YES

Ambient Light

YES

UV

YES

Use the UV sensor to let you know how much sun is coming through the window.

Occupancy

YES

Ambient Noise

NO

Alerts
Temperature Alerts

YES

Humidity Alerts

NO

Air Quality Alerts

YES

Low Battery Alerts

-

Features
Automations

YES

History Records

YES

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