Utility functions for calculating the Wet Bulb Globe Temperature (WBGT).

Get the warning category associated with a given WBGT.

Categories are based on the US National Weather Service (NWS), which issues the following suggested actions and impact prevention:

• 0 = No Warning.

• 1 = Working or exercising in direct sunlight will stress your body after

45 minutes. Take at least 15 minutes of breaks each hour if working or exercising in direct sunlight.

• 2 = Working or exercising in direct sunlight will stress your body after

30 minutes. Take at least 30 minutes of breaks each hour if working or exercising in direct sunlight.

• 3 = Working or exercising in direct sunlight will stress your body after

20 minutes. Take at least 40 minutes of breaks each hour if working or exercising in direct sunlight.

• 4 = Working or exercising in direct sunlight will stress your body after

15 minutes. Take at least 45 minutes of breaks each hour if working or exercising in direct sunlight.

Parameters

wbgt – Wet Bulb Globe Temperature [C].

Returns

An integer indicating the level of warning associated with the Wet Bulb Globe Temperature (WBGT).

Return type

category

Get wet-bulb globe temperature (WBGT) for outdoor conditions.

WBGT is a type of feels-like temperature that is widely used as a heat stress index (ISO 7243). It is incorporates the effect of temperature, humidity, wind speed, and mean radiant temperature (optionally including the effect of sun).

The WBGT outdoor formula is based on a mathematical model published by K. Blazejczyk et al. in 2014 [1] with the natural wet bulb temperature (Tnwb) based on the code written by Nick Burns.

Note

[1] Heat stress and occupational health and safety spatial and temporal differentiation, K. Blazejczyk, J.Baranowski, A. Blazejczyk, Miscellanea geographica regional studies on development, Vol. 18, No. 1, 2014

Parameters
• ta – Air temperature [C]

• mrt – Radiant temperature [C]

• ws – Wind speed at average human height [m/s]

• rh – Relative humidity [%]

Returns

Outdoor WBGT