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What is the Pollen Sense Normalized Misery Index?

The Misery Index provides a uniform scale from 0% to 100% to help allergy sufferers understand how varying concentrations of pollen, mold, and dust in the air will likely impact their symptoms. Unlike traditional binning methods, this index utilizes an exponential function to create smooth transitions between severity levels that better reflect human sensory experience. The Misery Index empowers people to more easily make informed decisions about outdoor activities and symptom management.

What is the Misery Index?

The Pollen Sense Normalized Misery Index (Misery Index) was designed to convey the effects of pollen concentration in the air on allergy sufferers. Allergen groups—such as tree, weed, and grass—have different concentration thresholds for what impacts allergy sufferers. The Misery Index provides uniformity across these various allergen groups to convey whether people with high sensitivity to allergens are likely to experience symptoms. Understanding the index's categories helps individuals with allergies plan their outdoor activities and take appropriate precautions.

The Four Misery Levels

The index is categorized into four levels: low, medium, high, and very high.

  • Low (0-24%): Most people with allergies are unlikely to experience symptoms.

  • Moderate (25-49%): People with allergies may experience symptoms.  

  • High (50-74%): Most people with allergies are likely to experience moderate to severe symptoms.

  • Very High (75-100%): People with allergies are likely to experience severe symptoms.

     

Scientific Derivation

  • The Misery Index is derived from the scale for pollens and molds developed by the National Allergy Bureau (NAB), featuring a few significant modifications.

  • While the NAB’s pollen scale uses a binning approach that labels a range of concentrations to a specific severity, the Misery Index translates these severity labels into a numerical percentage ranging from 0% to 100% 

  • This approach transforms the scale into an exponential function, creating smooth transitions between levels in a manner consistent with human sensory experiences.

Mathematical Formulas and Calibration

To convert between the Misery Index (M) and concentration (C), the index utilizes the following formulas:

M = log(C/b) / log(m)

C = b * m^M

  • The constants b (power) and m (factor) are found using a least squares regression to fit the exponential curve as close to the calibration points as possible. 

  • The values for b (power) and m (factor) are provided for each applicable category of allergen when you request data via our Sensor Customers API.

  • The calibration points correspond to the transitions between severity levels: 0.25 (low to medium), 0.5 (medium to high), and 0.75 (high to very high).

  • Because this calibration relies on a best-fit regression to the NAB's threshold concentrations, the actual concentration values at 25%, 50%, and 75% Misery may be somewhat different than the exact values at each threshold according to the NAB scale.

     

If you need to calculate the Misery Index from the raw Counts and Air Volume data, first calculate the concentration using the following formula:

C = sum( counts ) / sum( volume )

  • The concentration yielded by this approach will be in the units of particles per cubic meter, or PPM3.
  • This calculation should be done on a category-by-category basis, rather than summing counts across different categories, if the resulting concentration is to be used in finding the Misery Index.