1. Why Changing Humidity Made Colored Inks Shift in a 1902 New York Printing Factory
In 1902, a printing company in New York, USA, faced a problem where color inks shifted position when layered. The cause was that changes in the factory’s temperature and humidity altered the size of the printing paper. [1]
To solve this, Willis Carrier created an air-processing device and patented it in 1906. [1] The factory learned through painful experience that paper expands and contracts with moisture. It is important to note that Carrier’s device was for general air conditioning. We cannot call it the invention of the modern humidifier. However, it is an example of the idea of regulating air conditions with machines taking shape in a factory setting. [1]
So, when and for what purpose was the tool that "creates steam with electricity" born?
2. How a 1920s Electric Vaporizer Was Used for Medicine and Disinfection
In 1926, Max Katzman in the USA applied for a patent for an electric vaporizer. It was issued as US Patent 1,628,784 on May 17, 1927. [2]
The mechanism involves attaching carbon electrodes to a pair of conductive rods placed in water. Electricity flows through the water between the electrodes. It uses the fact that water resists electricity to heat the water itself and produce steam. [2] The patent also describes a safety feature where the circuit breaks if the water level drops and the electrodes are exposed.
The patent lists the uses as medicinal, disinfecting, and deodorizing devices. [2] This means the patent was not for a "humidifier." Katzman started a company in 1926 and manufactured this vaporizer, according to the company’s history. However, claims like "world’s first" are company statements, so we only use what is written in the patent here. [2]
The tool for creating steam with electricity first took shape near medicine and disinfection. When did the humidifier we use in heated rooms appear in Japan?
3. Which Four Types of Home Humidifiers Appeared in Japan Around 1970
Encyclopedias state that home humidifiers in Japan appeared by type as follows: centrifugal spray type in 1968, steam type in 1970, evaporative type in 1971, and ultrasonic type in 1974. [3] This means four types appeared within the six years from 1968 to 1974.
These years are not necessarily the year of invention, but the year the encyclopedia noted their "appearance." Since this timeline comes from a single encyclopedia, it is best to remember that they appeared around 1970. [3]
Only the 1974 date for the ultrasonic type is confirmed by another source. Wetmaster, a company making commercial and industrial humidifiers, states they began selling ultrasonic humidifiers ahead of the industry in 1974. [4]
The encyclopedia explains that demand for humidifiers grew as warm-air heaters became widespread. [3] In 1977, a machine that could both dehumidify and humidify in one unit was released. It used a refrigeration cycle for dehumidification and an ultrasonic method for humidification. [5]
Home machines gathered their types around 1970. How was the air inside homes changing at that time?
4. How Different Types of Winter Heating Change Indoor Humidity
A public relations magazine from the Tokyo Metropolitan Institute of Public Health (TMIPH) explains the relationship between heating types and humidity. Open-type heaters like fan heaters and oil stoves release water vapor from combustion. Air conditioners and electric heaters do not release water vapor, so when the room temperature rises, the relative humidity drops. [6]
Air can hold more water vapor when it is warm. If the temperature rises without adding more water vapor, the same air becomes drier.
The same material includes a graph from an old study showing that the survival rate of influenza viruses after 6 hours at 20.5–24°C (68.9–75.2°F) drops when the humidity is 50%. It recommends keeping humidity above 40% in winter by using humidification. [6] However, it does not state that humidification prevents influenza. It is listed only as one infection control measure.
Additionally, the Ministry of Health, Labour and Welfare’s standards for building hygiene require relative humidity in the rooms of applicable buildings to be between 40% and 70%. This applies to buildings with air conditioning systems, such as offices, and is not mandatory for homes. [7]
Humidifiers are machines that use water to raise humidity. How should we handle that water?
The TMIPH magazine explains that indoor humidity changes differently depending on the type of heating appliance. [6]
5. Why Humidifier Water Should Be Changed and the Humidifier Cleaned Every Day
Machines that handle water require daily care. Materials from the Chiba City Public Health Center on Legionella prevention provide guidelines for home humidifiers. Use tap water in the tank, change it completely every day, and clean the inside of the tank. This is to prevent the growth of bacteria like Legionella. [8]
The technology created to control humidity in factories has entered our homes. People who use water-based humidifiers at home also need to keep the water inside the machine clean. [8]
Tracing this history shows that the humidifier was formed by combining problems from separate places: factories, medicine, and the spread of heating.
6. How to Use a Hygrometer to Observe the Air in Your Home
If you have a hygrometer at home, compare the humidity in each room in the morning and evening. Note moments when humidity changes, such as before and after turning on the heater, or after a bath. Comparing your home’s numbers with the explanations in the Tokyo materials can provide clues about how different heating types affect humidity. [6]
If you have a humidifier, look at the instruction manual or the label on the unit to find out which type it is. Knowing if it is close to centrifugal spray, steam, evaporative, or ultrasonic makes the encyclopedia’s description from 1968 onwards feel more familiar. [3]
Touching the unit or the steam can cause burns. Check and clean the device with an adult, following the steps in the instruction manual. For more details, the original patent text [2] and Chiba City materials [8] are helpful. The TMIPH magazine [6] and Chiba City materials [8] summarize the basis for humidity and maintenance in Japanese.