Swimming, as a sport beneficial to both physical and mental health, is very popular among people. It is not only beneficial to improve the cardiopulmonary function, strengthen the body and shape the body, but also helpful to the recovery of physical injuries. 
Most of the swimming activities that people usually carry out are carried out in swimming pools. Most of the water in swimming pools is circulating water. The swimming pool water treatment equipment relies on circulating filtration and disinfection of the pool water, and the disinfectant plays a vital role.

Disinfectant refers to the preparation used to kill pathogenic microorganisms on the transmission media and make them harmless. It is different from antibiotics. Its main role in disease prevention is to eliminate pathogenic microorganisms outside the human body, cut off the transmission route of infectious diseases and achieve the purpose of controlling infectious diseases. Disinfectants are also often referred to as "chemical disinfectants". Swimming pool water and the human body skin direct contact, sometimes also can be inhaled. "All the organic matter in the water comes from decaying leaves, microbes and other dead life forms," said researcher Michael plewa, a professor of genetics at the university of Illinois.In addition to organic matter and disinfectants, there are swimmers' sweat, hair, shed skin, urine (one in five adults admit to urinating in the pool) and consumer products such as cosmetics and sunscreen they use." So the choice of disinfectant in the pool is closely related to human health.Around 4,000 people in the us are reported to go to hospital each year because of the effects of pool disinfectants.At present, the disinfectants in swimming pools in China are mainly chlorine disinfectants, and excessive chlorine is harmful to human body. Therefore, the disinfectant problem in swimming pools has become a topic of worldwide concern.

1.Common disinfectant for swimming pool water

The disinfectant in the swimming pool should be selected on the premise of not causing water and environmental pollution and not changing the water quality in the swimming pool. The disinfectant should have no stimulation to the human body or the stimulation is small, safe, non-toxic, no residue, and the bactericidal ability is efficient, rapid and lasting for a long time.In addition, the building structure, equipment and pipe corrosion is small.At present, the disinfectants used in swimming pools in China are usually chlorine disinfectants. The commonly used chlorine disinfectants include: inorganic chlorides, such as liquid chlorine, calcium hypochlorite, sodium hypochlorite, trisodium chloride phosphate, etc.Organochlorine compounds, such as sodium dichloroisocyanurate, trichloroisocyanurate, bromochlorheine, etc.Compared with inorganic chlorine, its properties are not stable, and it is easy to decompose when exposed to light, heat and moisture, thus losing its active components.Organochlorine is relatively stable, but is unstable when dissolved in water.The higher the pH value of the solution, the weaker the bactericidal effect. When the pH value is greater than 8.0, the disinfectant loses its bactericidal activity.Organics obviously affect its bactericidal effect;For every 10 degrees Celsius increase in temperature, the sterilization time can be reduced by 50 to 60 percent.

2.The harm of common disinfectant to human body

Chlorine-containing disinfectant is widely used because it is a broad-spectrum fungicide, and has the advantages of rapid action and low price.

However, its toxicity can irritate people's eyes and skin, thus causing red eyes and rashes. Long-term contact with pool water can make people's hair turn yellow, skin redness and swelling, vaginal itching, endocrine disorders, etc.

Chlorine-containing disinfectants can react with organic substances in water to produce many carcinogens, especially for developing children.

Due to the strong corrosion of some chlorine preparations, so the storage, transportation, practical operation and other use conditions of higher requirements, slightly careless will cause the occurrence of accidents.

The following will be the main use of several disinfectants are analyzed.

2.1 liquid chlorine

Liquid chlorine refers to liquid chlorine (C2), containing 100% effective chlorine, strong bactericidal force, and has a strong continued bactericidal ability and the ability to remove algae deodorization and odor.

Cheap and relatively skilled, it is widely used to sterilize water.

But the general dose is not effective to virus, pathogen and so on.

After joining the swimming pool, it is extremely acidic and needs to add a large amount of alkali to adjust the pH value. Moreover, the amount of liquid chlorine is not easy to control. If too much fails to fully react, it will lead to the formation of toxic chlorine gas mist, which is extremely harmful to human body.

So, at present liquid chlorine is used rarely in swimming pool water disinfection, but still have a few black heart businessman to seek profit and take this kind of disinfection method, should cause to notice.

2.2 bleaching powder(calcium hypochlorite)

The main component of bleach is calcium hypochlorite [Ca(CI0)2], which is a common disinfectant with good bactericidal effect and can be used in swimming pools of different water quality.

In acidic environment, its bactericidal force is strong and rapid reaction, high concentration can kill bud cells.

But calcium hypochlorite is not easy to preserve, see light, damp, heat and carbon dioxide (CO2) can be reacted.

Aqueous solution is alkaline and sediment, and there is a layer on the surface of water to human stomach and intestines mucous membrane, respiratory tract, skin generation is stimulated, can cause cough and the white float that affects eyesight.

2.3 bromochlorhein

Commonly known as bromine tablets (C5H6BrCIN202), the active ingredients are chlorine and bromine, usually in crystalline powder and white tablets.

It is more stable than chlorine, has a milder smell and is less sensitive to changes in pH than chlorine.

But bromine can be corrosive at high doses, causing intense irritation not only to the skin, eyes and cells, but also to swimming pool conditions

Next, a carcinogen, bromate (BrO3-), is produced.

2.4 trichloroisocyanuric acid

Trichloroisocyanuric acid (TCCA) is a chlorinated derivative of isocyanuric acid. Its molecular formula is C3N303Cl3, and its effective chlorine content is up to 90%.

Trichloroisocyanuric acid in the international promotion, because it is a high - efficiency, low toxicity, performance

A stable, broad-spectrum and fast disinfectant that can kill bacteria, spores, fungi, molds and cholera quickly and effectively

Isolated bacteria.

It has a strong effect on killing hepatitis a and hepatitis b virus, and also has a good disinfection effect on sexual virus and HIV.

TCCA is also the most widely used swimming pool disinfectant in China.

It is less irritating to the human body, as long as the residual chlorine content in the pool is kept within the limits set by the state, swimmers can rest assured.

The stabilizer in trichloroisocyanuric acid is cyanuric acid, cyanuric acid can make it stable under ultraviolet light, suitable for use in outdoor swimming pools, but use in indoor swimming pools will lead to over stability problems, high oxygen consumption.

TCCA in the form of solid effervescent tablets is not only convenient to use, but also makes it more water-soluble, can quickly form the bactericidal component chloric acid, and has the characteristics of - - tolerance to organic compounds.

The disadvantage is that harmful chlorine byproducts are produced.

3. The dosage of disinfectant should be reasonable

Because the disinfectant commonly used in swimming pools is mainly chlorine-containing disinfectant, excessive chlorine is very harmful to the human body, so it is crucial to control the dosage.The investigation report of national health supervision department shows: in recent years, the water of indoor and outdoor swimming pool is to use chlorine or chlorine.Chlorine in preparation for sterilization, disinfection of swimming pool water treatment process, not only will produce unpleasant excitant gas, also can make swimmers red eyes, yellow hair, skin easily crepe shrink, chlorine and ammonia in the water, urine, sweat and swimmers from other organisms, generated a lot of chloroform carcinogens and cross-linked with amine toxic substances.Among them trichloramine is a kind of stronger irritant gas, it is a kind of catalyst that causes asthma disease, can cause people lung permeability enhancement, make person easy

Asthma.

In addition, in order to increase profits, some dark natatorium to change the frequency of water to reduce costs.Due to the need to reduce the number of bacteria in the pool, excessive chlorine preparation is used to sterilize the pool water, which will result in more carcinogens of trichloromethane and irritating gas of trichloramine produced in the pool water, which will be more harmful to consumers and long-term poolside workers.For the adolescents who are in the period of growth and development, some damage caused by these toxic substances to them is great, should try to avoid contact with the residual chlorine substandard swimming pool water, do not go to the substandard swimming pool, if you feel uncomfortable while swimming, should leave as soon as possible and go to a doctor, so as not to cause irreversible consequences.