Air quality shield

This shield assesses air quality by measuring several compounds.

Compounds measured:

• Carbon dioxide (CO₂), which is measured in parts per million (ppm). In indoor spaces, harmful CO₂ levels begin in the 1,000 ppm to 2,000 ppm range, usually due to poor air exchange. Higher CO₂ levels become increasingly harmful. When CO₂ levels exceed 40,000 ppm, workers are in immediate harm due to oxygen deprivation.
• Total volatile organic compounds (TVOC), which is measured in parts per billion (ppb). TVOC is used to estimate the total Volatile Organic Compounds (VOC) that are present simultaneously in the air. Detecting TVOC in the 220 ppb to 660 ppb range indicate poor ventilation efficiency. Environment with TVOC readings in the 2,200 ppb to 5,500 ppb range are considered unhealthy and require intense ventilation.

The shield creates hazards for the following conditions:

• A single TVOC reading that exceeds a defined threshold.
• A single CO₂ reading that exceeds a defined threshold.
• A sustained CO₂ reading that exceeds a defined threshold for a defined length of time. Note: Testing for this condition was limited to simulated samples, since real-time testing requires a controlled environment in a dedicated laboratory.

This shield is supported by the following devices:

• Nordic Thingy:52™

To use this shield, your Worker Insights app must be version 1.1.0 or later.

Important: This shield requires final configuration before you can activate it. For more information, see Shields that require final configuration.

For information about activating this shield, see Activating shields for users.

Shield parameters

This shield has parameters with editable values. You can edit these values at a global level or for an individual worker. For information about editing shield parameters, see Editing shield parameters.

This shield has the following parameters:

• hazardTitles: A string value that represents the title of the notification when the shield alert displays. The default value is "Poor Air Quality". For information about changing this value, see Customizing a hazard title.
• highCO2ExposureThreshold: A numeric value that represents the threshold that triggers a hazard for a single CO₂ measurement. This value is measured in parts per million (ppm). The default value is 2,000.
• highTVOCExposureThreshold: A numeric value that represents the threshold that triggers a hazard for a single TVOC measurement. This value is measured in parts per billion (ppb). The default value is 2,500.
• CO2TWAThresholds:
  • Note: This parameter can be set by using the IBM Maximo Worker Insights API only.
  • Time Weighted Averages (TWA) are used to determine whether thresholds are exceeded. The TWA is assessed against an array with pairs of elements, hazardThreshold and durationInMinutes, to establish the maximum time that a worker can be exposed to a specific CO₂ level. By default, these values are 30,000 ppm for 15 minutes, and 5,000 ppm for 8 hours.
  • The array has the following form:

     [{ durationInMinutes: 15, hazardThreshold: 30000 },
      { durationInMinutes: 480, hazardThreshold: 5000 }]
    

  • This parameter is used with with the windowingStrategy parameter. If windowingStrategy is set to filter, set the CO2TWAThresholds parameter's value for hazardThreshold to 90% of the default values to account for numeric deviations.
• minHazardInterval: Specifies a delay in seconds before triggering a second hazard. The lower limit for this parameter is 10 seconds. The default value is 60 seconds.
• windowingStrategy: Determines which method is used to calculate Time Weighted Averages (TWA). Valid values include buffer and filter:
  • buffer uses all samples to compute an average that is based on a sliding window. This method is more memory intensive than filter. This is the default value.
  • filter uses the last sample value to maintain a moving average.
• sampleRate: A numeric value that represents the frequency with which data is sampled. This value is measured in hertz (Hz). The default value is 1 Hz, or one time per second.

Related information

• Shields
• Currently available IBM® Maximo® Worker Insights shields