Matter Implementation Guide¶

What is this?¶

The purpleair_api.PurpleAirMatterConverter module maps raw PurpleAir sensor readings to Matter-compatible device type structures per the Matter 1.5.1 Core Specification (Connectivity Standards Alliance, 2024).

This lets you expose PurpleAir sensors through any Matter-compatible ecosystem: Apple Home, Google Home, Amazon Alexa, Samsung SmartThings, Home Assistant, and more — by providing data in the format those platforms understand.

Prerequisites¶

pip install purpleair_api

You also need a PurpleAir Read API key (email contact@purpleair.com).

Quick Start¶

from purpleair_api.PurpleAirReadAPI import PurpleAirReadAPI
from purpleair_api.PurpleAirMatterConverter import PurpleAirMatterConverter

# Fetch sensor data
pa = PurpleAirReadAPI("YOUR_READ_API_KEY")
raw = pa.request_sensor_data(282168)

# Convert to Matter Air Quality Sensor
device = PurpleAirMatterConverter.to_air_quality_sensor(raw)

print(device["device_type"])
# {'id': 45, 'label': 'Air Quality Sensor', 'matter_version': '1.5.1',
#  'spec_reference': 'Matter 1.5.1 Core Spec — Air Quality Sensor Device Type ...'}

print(device["air_quality_summary"])
# {'epa_aqi': 68, 'epa_category': 'Moderate',
#  'matter_air_quality_rating': 'GOOD', 'matter_air_quality_rating_value': 2}

Three Device Types¶

Air Quality Sensor (full)¶

Use to_air_quality_sensor() to return all available PurpleAir measurements as Matter clusters:

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PurpleAir field	Matter cluster	Attribute
`pm2.5`	Air Quality (0x005D)	`measuredValue` (µg/m³ ×100)
`pm1.0`	Air Quality (0x005D)	`pm1Density` (µg/m³ ×100)
`pm10.0`	Air Quality (0x005D)	`pm10Density` (µg/m³ ×100)
`voc`	Air Quality (0x005D)	`vocDensity` (µg/m³ ×100)
(computed)	Air Quality (0x005D)	`airQuality` enum
(computed)	Air Quality (0x005D)	`aqiRating` enum
`temperature` °F	Temperature (0x0402)	`measuredValue` (°C ×100)
`humidity` %	Humidity (0x0405)	`measuredValue` (% ×100)
`pressure` PSI	Pressure (0x0403)	`measuredValue` (kPa ×10)

Matter Device Type: 0x002D (Air Quality Sensor)

Temperature Sensor¶

Use to_temperature_sensor() for a minimal device exposing only temperature.

Matter Device Type: 0x0302 (Temperature Sensor)

tmp = PurpleAirMatterConverter.to_temperature_sensor(raw)

Environmental Sensor¶

Use to_environmental_sensor() for temperature, humidity, and pressure on one endpoint without air quality clusters.

Matter Device Type: 0x0307 (Environmental Sensor)

env = PurpleAirMatterConverter.to_environmental_sensor(raw)

EPA AQI Calculation¶

PurpleAir does not natively provide AQI values. The module computes EPA AQI from PM2.5 using the official piecewise-linear formula:

from purpleair_api.PurpleAirMatterConverter import EpaAqiCalculator

pm25 = 25.0  # µg/m³
aqi = EpaAqiCalculator.pm25_to_aqi(pm25)
category = EpaAqiCalculator.aqi_to_epa_category(aqi)

print(f"AQI: {aqi} ({category})")
# AQI: 78 (Moderate)

AQI to Matter Rating Mapping¶

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AQI Range	EPA Category	Matter `airQuality`
0–50	Good	Excellent (1)
51–100	Moderate	Good (2)
101–150	Unhealthy for Sensitive Groups	Fair (3)
151–200	Unhealthy	Poor (4)
201–300	Very Unhealthy	Very Poor (5)
301–500	Hazardous	Extremely Poor (6)

Matter Scaled-Integer Convention¶

Matter protocol stores numbers as scaled integers to avoid floating-point complexity. This module encodes values as:

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Type	Formula
Temperature	`round(°C × 100)`
Humidity	`round(% × 100)`
Pressure	`round(kPa × 10)`
PM / VOC density	`round(µg/m³ × 100)`

Raw floating-point values are preserved in clusters[*]._raw_* fields for debugging and display.

Using with Home Assistant + Matter¶

Run python-matter-server or use the Home Assistant Matter Server add-on.
Expose the Matter structures through a bridge integration.
Home Assistant will discover the PurpleAir sensor as a Matter device.

Example bridge snippet (conceptual):

from purpleair_api.PurpleAirReadAPI import PurpleAirReadAPI
from purpleair_api.PurpleAirMatterConverter import PurpleAirMatterConverter
import matter_server  # python-matter-server

pa = PurpleAirReadAPI("KEY")
device = PurpleAirMatterConverter.to_air_quality_sensor(
    pa.request_sensor_data(282168)
)

# Feed device to your Matter bridge's device registration
matter_bridge.add_device(device)

Matter Specification References¶

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Resource	URL
Matter 1.5.1 Core Spec	https://csa-iot.org/developer-resource/specifications/
Air Quality Measurement Cluster (0x005D)	https://github.com/project-chip/matter
Temperature Measurement Cluster (0x0402)	https://github.com/project-chip/matter
Humidity Measurement Cluster (0x0405)	https://github.com/project-chip/matter
Pressure Measurement Cluster (0x0403)	https://github.com/project-chip/matter
EPA AQI Formula	https://www.airnow.gov/sites/default/files/2022-05/AQI-Basics-Calculation.pdf
python-matter-server	https://github.com/home-assistant-libs/python-matter-server
matter.js (reference implementation)	https://github.com/project-chip/matter.js

Design Notes¶

No new dependencies — only requests is required, keeping the package lightweight.
Stateless — PurpleAirMatterConverter methods are pure functions; all conversion is deterministic and testable without network access.
API-compatible response format — handles both bare {"sensor": {...}} and flat sensor dictionaries from the PurpleAir API.
Tested — see tests/test_purpleair_matter_converter.py for coverage including EPA AQI boundary conditions and unit conversion accuracy.