ESPHome AQI calculation based on PM2.5

aqi.yaml

// https://en.wikipedia.org/wiki/Air_quality_index#Computing_the_AQI
// Borrowed from https://github.com/kylemanna/sniffer/blob/master/esphome/sniffer_common.yaml

sensor:
  - platform: template
    name: "PM 2.5 AQI"
    id: pm2_aqi
    update_interval: ${pms_update_interval}
    unit_of_measurement: "AQI"
    icon: "mdi:air-filter"
    accuracy_decimals: 0
    filters:
      - skip_initial: 1  # Skip initial invalid data from PM2.5 sensor
    lambda: |-
      // AQI calculation based on PM2.5 concentration
      if (id(pm2).state <= 12.0) {
        // Good
        return ((50.0 - 0.0) / (12.0 - 0.0) * (id(pm2).state - 0.0) + 0.0);
      } else if (id(pm2).state <= 35.4) {
        // Moderate
        return ((100.0 - 51.0) / (35.4 - 12.1) * (id(pm2).state - 12.1) + 51.0);
      } else if (id(pm2).state <= 55.4) {
        // Unhealthy for Sensitive Groups
        return ((150.0 - 101.0) / (55.4 - 35.5) * (id(pm2).state - 35.5) + 101.0);
      } else if (id(pm2).state <= 150.4) {
        // Unhealthy
        return ((200.0 - 151.0) / (150.4 - 55.5) * (id(pm2).state - 55.5) + 151.0);
      } else if (id(pm2).state <= 250.4) {
        // Very Unhealthy
        return ((300.0 - 201.0) / (250.4 - 150.5) * (id(pm2).state - 150.5) + 201.0);
      } else if (id(pm2).state <= 350.4) {
        // Hazardous
        return ((400.0 - 301.0) / (350.4 - 250.5) * (id(pm2).state - 250.5) + 301.0);
      } else if (id(pm2).state <= 500.4) {
        // Hazardous Level 2
        return ((500.0 - 401.0) / (500.4 - 350.5) * (id(pm2).state - 350.5) + 401.0);
      } else {
        return 500; // Max AQI value
      }

text_sensor:
  - platform: template
    name: "PM2.5 AQI Label"
    id: pm2_aqi_label
    update_interval: ${pms_update_interval}
    lambda: |-
      // Categorize AQI into descriptive labels
      if (id(pm2_aqi).state <= 50) {
        return {"Good"};
      } else if (id(pm2_aqi).state <= 100) {
        return {"Moderate"};
      } else if (id(pm2_aqi).state <= 150) {
        return {"Unhealthy for Sensitive Groups"};
      } else if (id(pm2_aqi).state <= 200) {
        return {"Unhealthy"};
      } else if (id(pm2_aqi).state <= 300) {
        return {"Very Unhealthy"};
      } else {
        return {"Hazardous"};
      }