Which is more hygienic, drying clothes in the sun or drying them in a tumble dryer?

Winter is here again. I believe many people are like me. It is not easy to dry clothes after washing. Especially for those who have boarding students at home, the children bring back a pile of clothes after the holidays, but they can't dry them. At this time, the dryer becomes particularly important. Some netizens also said that the dryer is indeed convenient, and the sun drying is a tradition passed down by our ancestors. So which one is better and more hygienic, drying by drying or drying in the sun? Let's talk about it today.

01. About hygiene

I can't help but think of the days when I was dominated by the biological laboratory. Speaking of hygiene, I believe that people who have done biological experiments must have a deep understanding, or simply say that they are extremely familiar with it, because this is a very basic operation in the biological laboratory. If you can't do the basic hygiene problem well, the subsequent experiments are out of the question, especially the common sterilization operation in the laboratory, which is very familiar to people who do molecular experiments. Therefore, from an experimental perspective, few people really worry about this issue. Sunlight? What is the use of sunlight? Throwing experimental equipment in the sun to cultivate, isn't that raising bacteria yourself?

But back to the question of drying clothes in the sun and drying them in the sun, I think it is still necessary to clarify. After all, drying clothes in the sun has been a popular practice for thousands of years, and people have a very strong inertial dependence on it. So, which one is better? Today, I will talk to you from the perspectives of microorganisms and particulate pollutants.

02. First, let’s talk about microbial issues

Today, we are very familiar with microorganisms, such as various bacteria, fungi and viruses that we often mention. This is also the most concerned health issue. After all, common problems that cause diseases are often caused by microorganisms. This is why everyone is very worried about microorganisms such as various pathogens today. As our human protective equipment, the hygiene of clothes is also a key issue. Microorganisms are everywhere in the air. Airborne microorganisms are something that is easily overlooked by many people, but objectively exists. If you think about those diseases that are transmitted through the air, you will generally understand this thing. In fact, there are a large number of species in the air that are resistant to dry environments and ultraviolet rays, which have become an important source of infection.

However, air is everywhere, and so are microorganisms. In this case, how to prevent the growth of microorganisms becomes a crucial issue.

What are the basic conditions for the survival of microorganisms? Nutrition? Temperature? In fact, the answer is not entirely true. The basic condition for the survival of microorganisms is: water. As the source of life, water is a necessity for all life, and microorganisms are no exception. As long as there is water, there is a prerequisite for the reproduction of microorganisms. Therefore, from a hygienic point of view, removing water is the first priority. The longer the microorganisms exist in the water, the greater the possibility of breeding bacteria, and naturally the more unhygienic it is. Therefore, if you want to ensure hygiene, the best way is to dehydrate the clothes as quickly as possible after washing.

In fact, the growth curves of most bacteria basically follow a rule, which is divided into a delayed phase, a logarithmic phase, a stable phase and a decay phase. Take Escherichia coli, the most common pathogen in our lives, as an example.

The bacteria were still fine at the beginning of the culture, in the delayed period, and were in an adapting state. The overall number was small and the growth rate was slow. However, as time went on, after about 3 hours, it began to enter the logarithmic phase, and its amplification curve began to accelerate, showing a rapid upward trend. At this time, the size of the bacterial colony expanded rapidly.

Therefore, in order to prevent the bacterial flora from entering the logarithmic growth period, it is best to dehydrate the clothes within this time range to keep them dry. What about the comparison between a dryer and drying clothes?

The drying temperature they can provide is 65-70℃, and then last for 75 minutes to dry the clothes, which can basically keep the bacteria in its delay period and avoid entering the logarithmic period to the greatest extent.

But what about drying in the sun? Under normal circumstances, with good ventilation and sunlight, most clothes, except for thin summer clothes, need to be dried for more than 5 hours. At this time, the bacteria are already in the logarithmic period, showing an exponential increase. If it is cloudy and rainy, especially during the rainy season, this problem is even more troublesome. Basically, bacteria will breed in large numbers, causing the clothes to have a strange smell. In fact, it is bacteria that grow, which is naturally unhygienic.

Therefore, from the perspective of breeding microorganisms, the dryer is much more powerful than drying in the sun.

03. The problem of particle pollution

In recent years, everyone knows that a very serious problem is air pollution, especially the explosion of PM2.5, which has attracted the attention of countless people. An important problem among air pollutants is dust, which is also called particulate pollutants in academic terms. Many of these substances can be suspended in the air for a long time and can be transported over long distances.

Particle pollutants often contain various chemical components, such as organic carbon, nitrates, sulfates and ammonium salts, which are irritants and can easily affect the skin. In addition, there are pollen and other substances in the air, which can easily cause allergies in some people with sensitive constitutions.

If you dry your clothes, you can avoid contact with these particulate pollutants, which is perfect. But if you hang your clothes outdoors, the clothes will become a huge absorption container, causing a large amount of particulate pollutants to be adsorbed on the body, and finally causing damage to the health of the body. Therefore, when the pollution is serious, you should avoid drying clothes outdoors.

So now, in fact, dryers have become standard equipment in many households, and it is also very popular in developed countries (I remember someone mentioned that dryers are everywhere in the United States). Why? One of the important factors is that dryers are more hygienic, and of course, it is also because of our improved economic capabilities.

04. What types of dryers are there?

Of course, dryers are also different. According to their principles, they can be roughly divided into three types.

**1. Hot air type. **To put it simply and roughly, it is equivalent to using a hair dryer to dry clothes. The advantage is that it is cheap. Many cheap dryers on Taobao are basically of this type. There are naturally many disadvantages. One is that the efficiency is very low, and the other is that it consumes a lot of electricity. If you have tried to use a hair dryer to dry some clothes, you will know that the efficiency and power consumption are simply shocking. And there is a key problem that is the discharge of moisture, so a relatively open space is needed for discharge, so generally it can only be discharged in places such as balconies. In addition, the damage to the fabric of the clothes itself is not small, so it is highly not recommended.

**2, Condensation type. **This is the mainstream dryer in the market. It also uses an electric heater to heat and dry, but the advantage is that it adds a condensation component, so that the moisture generated during the drying process can be converted into liquid and discharged. In this way, the space required for moisture discharge is also smaller, and it is flexible to place and can meet different scenarios. Therefore, it has become the mainstream dryer in the market. Of course, compared with hot air dryers, its energy efficiency has also been greatly improved.

**3. Heat pump type. **This is the configuration of the current high-end dryer. It is a technical upgrade and is closer to the air conditioner we use daily. The compressor of the high-end dryer will have a good heat treatment during the processing process. The hot and humid gas is processed into liquid water and discharged, and the heat generated by the liquefaction process is absorbed and used for further drying. This reciprocating cycle greatly improves energy efficiency, and because it is an internal energy exchange as a whole, it further reduces the need for heat dissipation and exhaust, and basically does not require placement space.

Of course, clothes drying itself is a dynamic process, in which moisture is also a dynamic change process. This is undoubtedly a challenge to the single heat pump mode and can easily affect the fabric of clothes. Therefore, high-end dryers now use dual frequency heat pump drying.

Of course, even if the above are not considered, what about the time cost? Drying clothes in the sun takes at least several hours to a day. If it happens to be the rainy season, it will be a disaster, and the clothes will not dry at all.

But a dryer can easily solve the problem in about an hour regardless of the time and environment. Time is money.

Through the above comparison, I believe everyone has understood which is better for sterilization, drying or sun drying.