Data processing
Overview of Data Domain
Environmental sensors are devices designed to detect and measure various environmental parameters such as temperature, humidity, air quality, and light intensity. Research indicates that environmental factors play a significant role in health outcomes, yet most of these studies have focused on outdoor conditions at a broad city or regional scale. They often overlook the critical aspect of the individual's home environment.
In the AI-READI study, a custom-designed sensor unit (LeeLab Anura) was utilized to obtain environmental sensor data from each subject's home for a period of 10 days. Clinical research coordinators provided the subjects with the device along with take-home instructions to place the device in an area frequently used. Upon return, the subject was asked to make a note of the location of the environmental sensor. The sensor then recorded particulate matter counts (PM 1.0, 2.5, 4, and 10), temperature, relative humidity, volatile organic compounds (VOCs), nitrogen oxides (NO and NO2), and 11 multi-spectral light intensity measurements.
Variables included in Data Domain
Light levels (lch)
Light level measurement for environmental sensors assesses the intensity of illumination in an environment, providing data on brightness or darkness to inform on conditions ranging from dimly lit interiors to bright outdoor spaces. Relative intensity is the unit of measurement used and it indicates the strength of light signals detected by sensors relative to a reference point or standard. This measurement is also conducted across different wavelengths, including 415nm, 445nm, 480 nm, 515nm, 555nm, 590 nm, 630 nm, and 680 nm and 910 nm, providing insights into variations in light levels across various wavelengths.
More information about the AS73411 11-channel multispectral digital sensor is available here.
Particulate matter (pm)
Measuring particulate matter involves quantifying the concentration of fine inhalable particles in the air, expressed as the count per cubic centimeter. This measurement is specific to the size of the particles with pm 1, pm 2.5, pm 4, and pm 10, representing diameters ranging from 0.3 to 1 um, 0.3 to 2.5 um, 0.3 to 4 um, and 0.3 to 10 um, respectively. Some common sources of PM10 include dust from roads, farms, dry riverbeds, construction sites, and mines.
Here is a document describing the SEN55 particle matter, temperature, humidity, VOC and NOx sensors.
Temperature (temp)
Temperature quantifies the level of warmth or coolness within a substance or surroundings. The environmental sensor measures the ambient temperature of its surroundings, typically reported in degrees celsius.
Humidity (hum)
Humidity indicates the amount of water vapor in the air, reflecting an environment's moisture level. The measured variable is relative humidity, expressed as a percentage, which indicates the current amount of water vapor compared to the maximum it can hold at that temperature. A relative humidity of 100% indicates that the air is fully saturated and cannot hold any more moisture.
Volatile Organic Compound (voc)
Volatile Organic Compounds (VOCs) are a group of organic chemicals that easily evaporate into the air at room temperature. They are emitted from common foods such as wine, cheese, vinegar, salad dressings, and bananas. Non-food sources include paints, cleaning products, furniture, and building materials. The environmental sensor measures VOC levels and assigns a VOC Index. It assesses the current VOC status relative to recent history in a room, akin to our nose adjusting to air changes. Using a 24-hour moving average as a baseline, the VOC Index detects variations in VOC levels. This index ranges from 0 (low or none noticeable) to a maximum of 500.