As a health and hygiene expert with extensive knowledge in the field of microbiology and public health, I have often been asked about the best practices for handwashing. The question of whether to use cold or hot water when washing hands is a common one, and it's important to provide a comprehensive answer based on scientific evidence and practical considerations.

Handwashing is a fundamental aspect of personal hygiene and disease prevention. It is one of the most effective ways to prevent the spread of infections and illnesses, including the common cold, flu, and even more serious diseases like COVID-19. The act of washing hands with soap and water is not only about removing visible dirt but, more importantly, about eliminating germs and bacteria that are not visible to the naked eye.

When it comes to the temperature of the water used for handwashing, both hot and cold water have their advantages and disadvantages. Let's delve into the details:

Hot Water:
- Thermal Comfort: Hot water is generally more comfortable to use, especially in colder climates or during the winter months. The warmth can be soothing and can improve the overall handwashing experience.
- Grease Removal: As the FDA has noted, hot water is more effective at removing oils from the skin. These oils can trap bacteria and other microorganisms, making them more difficult to wash away with soap alone.
- Skin Health: However, it's important to note that water that is too hot can be detrimental to the skin. It can strip away the natural oils that keep the skin moisturized, leading to dryness and irritation.

Cold Water:
- Preservation of Skin Barrier: Cold water is less likely to strip the skin of its natural oils, helping to preserve the skin's barrier function. This can be beneficial for individuals with sensitive or dry skin.
- Environmental Considerations: Using cold water is more energy-efficient and has a lower environmental impact compared to heating water, which requires energy consumption.
- Bacteria Removal: While cold water is less effective at removing oils, it is still capable of washing away dirt and bacteria when used with soap. The mechanical action of rubbing hands together under running water, along with the soap's detergent action, is the primary method of removing germs.

The Role of Soap:
Regardless of the water temperature, the use of soap is crucial. Soap helps to lift dirt, grease, and bacteria from the skin, allowing them to be rinsed away with water. The mechanical action of lathering and scrubbing is what truly aids in the removal of germs.

Conclusion:
The optimal approach to handwashing is to use water at a temperature that is comfortable for you, ensuring that you can wash your hands thoroughly without causing skin irritation. The key is not the temperature of the water but the duration and technique of washing. It is recommended to wash hands for at least 20 seconds, covering all surfaces of the hands, including the backs of the hands, between the fingers, and under the nails.

Remember, the goal is to reduce the number of germs on your hands to a level that is not harmful to health. Both hot and cold water can achieve this when used correctly with soap. It's also worth noting that public health guidelines often emphasize the importance of handwashing technique over water temperature.

Now, let's proceed to the translation of the above discussion into Chinese.

read more >>

In its medical literature, the Food and Drug Administration states that hot water comfortable enough for washing hands is not hot enough to kill bacteria, but is more effective than cold water because it removes oils from the hand that can harbor bacteria.read more >>