Complete tutorial : https://help.sinric.pro/pages/tutorials/air-quality-sensors/mq135.html

AirQualitySensor.json

{
  "name": "Air Quality Sensor",
  "description": "Air Quality Sensor",
  "deviceTypeId": "5ff0b112994fd31b7d5e8065",
  "capabilities": [
    {
      "id": "5ff0b41b994fd31b7d5e8961",
      "mode": {
        "instanceId": "modeInstance1",
        "locale": "en-US",
        "modeName": "Air Quality",
        "nonControllable": true,
        "modeValues": [
          "SEVERE",
          "VERY POOR",
          "POOR",
          "MODERATE",
          "GOOD"
        ]
      }
    },
    {
      "id": "5ff0b45f994fd31b7d5e89c2",
      "range": {
        "instanceId": "rangeInstance1",
        "locale": "en-US",
        "rangeName": "ppm",
        "minimumValue": 1,
        "maximumValue": 1024,
        "precision": 1,
        "unitOfMeasure": "600e7986a7a09c3f3230f8fb",
        "presets": [],
        "nonControllable": true
      }
    },
    {
      "id": "62a707bd9e2f39090569e2d3"
    }
  ]
}