CHARACTERISTICS OF INDOOR RADON AND THORON CONCENTRATIONS IN CAVE DWELLINGS IN GANSU PROVINCE, CHINA.

Area of Science:

• Environmental Science
• Radiological Protection
• Indoor Air Quality

Background:

• Cave dwellings in Gansu Province, China, represent unique living environments.
• Understanding indoor air quality, specifically radioactive gas concentrations, is crucial for occupant health.
• Radon (222Rn) and thoron (220Rn) are naturally occurring radioactive gases that can accumulate indoors.

Purpose of the Study:

• To evaluate diurnal and seasonal variations of indoor radon (222Rn) and thoron (220Rn) concentrations.
• To compare these variations across four distinct types of Chinese cave dwellings: 'ground', 'open-cut', 'aboveground', and 'underground'.
• To identify factors influencing radon concentration fluctuations, such as dwelling type, exhalation from building materials, and ventilation.

Main Methods:

• Short-term measurements of indoor radon (222Rn) and thoron (220Rn) were conducted.
• Data collection occurred in four different types of cave dwellings in Gansu Province, China.
• Measurements were taken to assess both diurnal (day/night) and seasonal (summer/winter) variations.

Main Results:

• Indoor radon (222Rn) concentrations were generally higher during nighttime than daytime in 'ground' and 'open-cut' dwellings during summer.
• This diurnal fluctuation of radon (222Rn) was not observed in winter.
• Daily indoor radon (222Rn) levels were higher in summer than in winter for most dwelling types, influenced by dwelling type, material exhalation, and ventilation.
• Thoron (220Rn) showed minimal clear variations across different conditions.

Conclusions:

• Indoor radon (222Rn) concentrations exhibit significant diurnal and seasonal variability in Chinese cave dwellings, particularly influenced by season and dwelling type.
• Ventilation and exhalation from building materials are key factors affecting radon (222Rn) levels.
• Thoron (220Rn) concentrations appear to be less variable compared to radon (222Rn) in these environments.