We spend more time indoors than we think. According to the National Institute of Environmental Research and the National Statistical Office , we stay indoors more than 20 hours a day. We only worry about the outside air, but indoor air has a significant influence on our daily lives. In this book, we will study the DHT22, MH-Z19B, ZE08-CH2O, CCS811, GDK101 indoor air environmental sensors.
Chapter 3: Indoor Air Environmental Sensors
C301 DHT22 Temperature-Humidity Sensor
The DHT22 temperature and humidity sensor uses the AM2302 sensor. Before release, sensors are calibrated in temperature and humidity during production. When the microcomputer inside the sensor is detected, the correction factor values stored in the memory are used to provide accurate temperature and humidity values.
Fine dust is affected by temperature/humidity
As the air circulates and air pollutants increase their time spent in the air, the human body is more negatively affected.
[Air pollutants affected by temperature/humidity]
Dust: silicosis, pneumoconiosis
Combustible gas (CO, NO2, SO2, etc.): chronic lung disease, increased airway resistance, etc.
Formaldehyde: eye, nose, throat irritation, dizziness, cough, diarrhea, skin disease, emotional anxiety, memory loss
When humidity is low, and the air is dry, the mucous membrane becomes dry. The natural immunity from bacterial infection in the airway worsens, resulting in respiratory diseases such as colds and the flu. Also, symptoms of various diseases such as allergies and asthma worsen. On the other hand, high humidity allows various microbes to reproduce. In particular, bacteria such as fungi causes asthma, allergies, and rhinitis symptoms.
[Effects of temperature/humidity on the human body ]
The indoor humidity criteria for the influence of the human body, skin temperature, and humidity are as follows.
C302 MH-Z19B Carbon Dioxide (CO2) Sensor
Winsen's MH-Z19B sensor is a non-dispersive infrared (NDIR) carbon dioxide sensor. MH-Z19B sensors can be used for air purification systems (HVAC), indoor air quality monitoring, smart appliances, schools, and air cleaners.
Carbon dioxide is released every time a person breathes.
Carbon dioxide is released every time a person breathes. Closing doors and windows tightly to increase the effectiveness of air purifiers can lower the concentration of fine dust, but the concentration of carbon dioxide will increase. Depending only on air purifiers to reduce fine dust can have a negative effect on our bodies because of the increased concentration of carbon dioxide
In poorly ventilated spaces (e.g., classrooms, offices, bedrooms, air-conditioned trains or airplane rooms), carbon dioxide levels can exceed 1,000 parts per million (U.S. University of Wisconsin study).
There is no health damage at 1,000 ppm, but sensitive people will feel uncomfortable, and prolonged exposure may compromise thinking skills.
At 1,000 to 2,000 ppm, the air feels stuffy and can cause sleepiness. Poor concentration and mild headaches occur.
When windows are closed, and the air purifier is turned on, instead of using the fine dust standard concentrations, we have to use the standard concentration of carbon dioxide to understand its effects on the human body.
C303 ZE08-CH2O Formaldehyde (HCHO) sensor
The ZE08-CH2O sensor is a gas sensor that can detect formaldehyde. The electrochemical principle is used to detect formaldehyde in the air. It also has a built-in temperature sensor to calibrate the sensor value. Output signals include analog and digital UART outputs.
Formaldehyde is a very toxic substance to the human body.
Formaldehyde is a very toxic substance to the human body. When the body is exposed to formaldehyde, symptoms of disease begin to appear. In particular, it is included in the interior materials of buildings, and is also the main culprit of the sick house syndrome and the new building syndrome. Health effects such as irritation symptoms such as eyes, nose and throat, allergic reactions, shortness of breath, asthma, headache, etc. Respiratory system abnormalities, skin diseases and allergic symptoms may worsen.
C304 CCS811 TVOC (Total Volatile Organic Compounds) Sensor
AMS CCS811 sensors have metal oxide (MOX) gas sensors that can monitor indoor air quality. It consists of a microcontroller unit (MCU) that detects a wide range of volatile organic compounds (VOCs) with digital gas sensors. The integrated MCU of the CCS811 sensor manages the sensor drive mode and raw sensor data measured during VOCs detection.
The term volatile organic compound (tvoc) is collectively referred to as VOCS.
TVOC (Total Volatile Organic Compounds) windows closed and air purifier on unexpected ambush
TVOC adversely affects the human body depending on its type (degree of toxicity), concentration and duration of exposure. It is carcinogenic and causes nervous system disorders through skin contact or respiratory inhalation.
C305 GDK101 Radiation (gamma ray) sensor
The GDK101 sensor made by FTLAB can measure gamma rays (X-ray detection). It has a solid-state gamma sensor module with a sensitive 10-pin photodiode and a trans-impedance amplifier circuit controlled by the MCU.
Radiation exposures can be divided into acute and chronic exposures  depending on the duration of the exposure. Acute Radiation Syndrome (ARS) is a temporary sudden exposure to large amounts of radiation, resulting in a temporary decrease in the number of white blood cells and physical abnormalities such as vomiting, hair loss, and skin changes as exposure dose increases. Chronic Radiation Syndrome (CRS) occurs after low-level radiation exposure. Symptoms such as skin atrophy, formation of fibers in the skin due to previous burn marks and eye cataracts that disappear after eye wounds occur.
Purchasing a book
[Arduino Sensors for Everyone] The book is available for purchase on Google Book and Apple Books.
In this book, you will learn how to use the PMS7003, GP2Y1010AU0F, PPD42NS, SDS011 Fine Dust Sensor, DHT22 temperature/humidity sensor, MH-Z19B carbon dioxide sensor, ZE08-CH2O formaldehyde sensor, CCS811 total volatile organic compound (TVOC) sensor , GDK101 radiation (gamma ray) sensor, MQ-131 ozone (O3) sensor, MQ-7 carbon monoxide sensor, MICS-4514 nitrogen dioxide sensor, MICS-6814 ammonia sensor, DGS-SO2 sulfur dioxide (SO2) sensor, BME280 atmospheric pressure sensor, GUVA-S12SD ultraviolet (UV) sensor, MD0550 airflow sensor, and QS-FS01 wind speed sensor.
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