Formaldehyde is a colorless gas with a pungent smell and can be dissolved in water. 40% formaldehyde solution is what we often call formalin. Formaldehyde is ubiquitous in nature, and all living things, including trees, animals and human bodies, contain formaldehyde. (Formaldehyde is a pure natural product, haha) These formaldehyde are metabolized by amino acids (an important part of protein). So it is normal for trees to contain formaldehyde. Even solid wood has no formaldehyde at all.
Is formaldehyde really that terrible?
There is a classic saying in Zhihu: No matter the dose, it is a hooligan to talk about toxicity. In people's words, if you drink too much water, you will support it, and if you eat too much salt, it will be dull; You can't stop it since ancient times. Don't eat cyanide if you have nothing to do.
An internationally accepted index is called the lethal dose of half, which is the dose that causes half of the experimental animals to die in the experiment. For example, the lethal dose of water >: 90000mg/kg (body weight), the experimental object is rats, and the route is oral. On a person, one breath is almost 1 1 kg of water. Doing so is simply a death wish.
Monosodium glutamate 16600mg/kg, ethanol (alcohol) 9900mg/kg, sodium chloride (salt) 3000mg/kg. But we also eat these things every day. The so-called virulence is only because the lethal dose is very small. Not because it is pure natural, it must be non-toxic; There must be something wrong not because of artificial synthesis.
What is the harm of formaldehyde?
We have been using formaldehyde for more than 100 years, but we have only deepened our understanding of its harm in the past 20 years. IARC, an international agency for research on cancer under WHO, issued the announcement 153 in 2004. Experiments by 26 scientists from 10 countries show that formaldehyde is a definite carcinogen and can cause nasopharyngeal carcinoma (smoking can also induce nasopharyngeal carcinoma).
Then in 2006, IARC published "IARC Human Carcinogen Assessment Paper" in Volume 88, which directly wrote formaldehyde. The English version is 287 pages long and records the formaldehyde content in wood, board and paper products in detail. A large number of studies around the world show that long-term high-concentration exposure to formaldehyde will increase the incidence of nasopharyngeal carcinoma, especially among workers in related industries. The incidence of nasal sinus cancer has also increased, but it is impossible to judge whether it is caused by formaldehyde or sawdust during processing.
The influence on leukemia is the topic that everyone is most concerned about. The subjects of study are funeral, autopsy, medicine and scientific research personnel, who need to be exposed to formalin frequently. Workers in plate processing plants are also among the key research objects. The results showed that the longer the workers were exposed to formaldehyde, the more likely they were to die of leukemia.
The final conclusion of this paper is as follows: There is strong but non-toxic evidence that there is a causal relationship between leukemia and occupational exposure to leukemia. There are real and effective cases to prove the relationship between occupational exposure to formaldehyde and leukemia, but the sample size is too small to fully prove that formaldehyde can directly cause leukemia.
By 20 15, IRAC's updated list of carcinogens classified by site and cancer name has clearly indicated that there is sufficient and strong evidence to prove that formaldehyde can induce leukemia. At present, formaldehyde, benzene, caffeine, alcohol and tobacco are listed as 1 carcinogens in the IARC carcinogen list. This carcinogen has conclusive evidence that it can induce cancer.
On 20 15, the American Journal of Maternal and Child Health published an article entitled "Formaldehyde Exposure during Pregnancy". The paper fails to prove that exposure to formaldehyde will have an impact on pregnant women and fetuses.
On the page of CDC in the United States, there are the following tips: (excessive formaldehyde) may not pose a great threat to pregnant women and fetuses, but pregnant women should pay attention to avoid exposure to formaldehyde.
What is the safety standard of formaldehyde?
Just like drinking two mouthfuls of wine and two mouthfuls of coffee will not cause cancer, formaldehyde also has its own safety standards. In the latest version of 20 10 Code for Indoor Environmental Pollution Control of Civil Construction Engineering (GB 50325), it is stipulated that:
A class of civil construction projects, including houses, office buildings, hospitals and schools, shall not contain more than 0.08mg/m? .
This is a mandatory national standard.
How did interior decoration come into being?
We often hear the saying of so-and-so resin, and always think it is pure natural.
Resin originally refers to some secretions produced by natural trees, but synthetic similar components can also be called resin, called synthetic resin.
Phenolic resin (bakelite), urea-formaldehyde resin and melamine-formaldehyde resin are the most important adhesives in building materials processing.
The above three synthetic resins are made by the reaction of phenol, urea and melamine with formaldehyde.
The process is simple and the raw materials are easily available, so urea-formaldehyde resin is still one of the cheapest adhesives at present.
Unfortunately, it is also one of the most dangerous adhesives.
Urea-formaldehyde resin and its modified products account for 90% of all kinds of wood-based panels in wood processing industry.
Ranked second in the priority control list of toxic chemicals in China.
At present, the industry is actively developing methods to reduce formaldehyde volatilization in urea-formaldehyde resin, including modifying and improving curing agent.
These adhesives are the most direct source of people's impression of formaldehyde, and also the reason why they hate plates.
In addition to plates, gypsum boards, paints, plastic products and adhesives commonly used in suspended ceilings may also contain formaldehyde.
Heating will lead to faster separation of formaldehyde from the adhesive, and formaldehyde can be dissolved in water. Therefore, when heating is turned on in the north, the formaldehyde concentration will be higher than usual in Huangmei days or hot and humid seasons in the south.
Compared with the cheapest urea-formaldehyde resin, melamine-formaldehyde resin is several times more expensive and releases less.
Melamine formaldehyde resin will be used to modify urea-formaldehyde resin or replace urea-formaldehyde resin.
Therefore, melamine board (melamine board) is also called eco-board, which is really environmentally friendly.
But melamine board only means that its surface pattern layer is impregnated with melamine formaldehyde resin, which has nothing to do with the material used in the intermediate board.
Moreover, in order to save costs, bad manufacturers will add some urea-formaldehyde resin to the decorative surface of melamine board.
This part of urea-formaldehyde resin has no cover of veneer and edge sealing, and directly volatilizes formaldehyde.
In addition, many other adhesives have not been widely used because of their poor performance or high price.
Does E0 level exist?
Among the national standards of formaldehyde emission limits in interior decoration materials, wood-based panels and their products published in 200 1, only E 1 and E2 standards have appeared and are still in use today. The standard of E 1 is 1.5mg/L, and E 1 can be used indoors.
The standard of E2 is 5.0mg/L, and E2 material can only be used indoors after facing treatment.
In 2006, the current national standard of impregnated paper veneer wood-based panels (density board and particleboard) directly quoted the above standard 0 1.
However, in the standard of impregnated paper laminated wood flooring (laminate flooring) in 2007, we did refer to the E0 level description.
However, the E0 level here only refers to the single monitoring index of formaldehyde emission.
Instead of representing the quality level of the floor itself.
Among the current national standards, only the national standard for laminate flooring mentioned E0 level of formaldehyde.
The E0 level in the board is extended from the concept of floor.
There is no problem in theory, but the national standard lags behind.
Speaking of national standards, the current national standards are generally regarded as too low. Many standards (such as "Standard for Ordinary Plywood" of 20 15) point the final data to the national standard of "Formaldehyde Emission from Wood-based Panels and Products" of 200 1, but this national standard is now 15 years away. The harm of formaldehyde was not taken seriously when it was formulated. At that time, formaldehyde was only a "possible carcinogen". Moreover, when formulating the standards, the standards of the European Union and Japan in the 1990s were referred to.
How to avoid and remove formaldehyde?
First, avoid excessive decoration. Aside from the subjective aesthetic things, let's make a simple algorithm: 1.5mg/L E 1 plate matching 10L Is the formaldehyde emission large? Or is the formaldehyde emission of 50L 0.5mg/L E0 board large? A completely unnecessary wine cabinet and a grandiose and useless ceiling will add a source of formaldehyde release to the home.
Second, within the budget, choose the most expensive materials you can afford. Many people must have heard this saying when buying shoes, bags and suits. Because the price/performance ratio is really suspicious. Slowly, everyone found that a penny is worth a penny, a dime is twenty cents, and a dollar is thirty cents. Good things are expensive, not only making money, but also technical barriers.
For example, we often say that imported egg plates. Their Chinese quality inspection report was found in the German official website of EG Company, which clearly indicated that their formaldehyde emission was 0.3 mg/L, which was less than the national standard E 1( 1.5mg/L) that should be referred to, and also less than the newer national standard E0(0.5mg/L) for flooring, reaching the F4 star level in Japan. In order to reduce the formaldehyde emission of 0.2 mg per liter, the price is twice as expensive as that of ordinary domestic E0 particleboard. Is the quality good? All right. Is it cost-effective? number
Third, it is better to open the window often for ventilation than anything else. Green plants have little effect on absorbing formaldehyde. Any plant in addition to formaldehyde method is not worth recommending and using.
The charcoal bag does have adsorption function, but it is passive and can only adsorb formaldehyde near itself. However, the charcoal bag must be replaced in time after absorbing formaldehyde, otherwise it will become a source of pollution that emits formaldehyde. Diatom mud wall has the same function as carbon bag, but it is more difficult to clean after it absorbs formaldehyde saturation, unless the wall skin is shoveled off. Relying solely on diatom mud is equivalent to transferring formaldehyde in the house from plates and floors to the walls.
An air purifier with an activated carbon inner core can also have the same effect as a carbon bag, but the inner core should be replaced in time, otherwise formaldehyde will be blown out again. The function of fresh air system is the same as that of window ventilation, but the air volume is small. The way to put a pot of water is to use the solubility of formaldehyde in water. But a basin of still water, free in the air, has a particularly high concentration. How much formaldehyde can it absorb? Pomelo peel, lemon, vinegar steamed, pineapple are all nonsense, purely using their own taste to cover up the smell of formaldehyde, treating the symptoms rather than the root cause.
The most efficient and effective way is to open the window for ventilation. In the case of good outdoor air, it is more effective to open the cupboard and open more windows for air than the whole mess. In the case of improper ventilation, using fresh air, charcoal bag and air purifier is our most recommended method.
Fourth, don't blindly believe in "hanging a house". How long will the renovated house hang? Three months? Half a year? A study by the Hong Kong Polytechnic University shows that after two years of residential decoration, the concentration level of formaldehyde gradually approaches the old house. Although the concentration becomes smaller, formaldehyde will continue to be released, which may last for a long time. These standards cannot be judged, so it is better to buy a portable household formaldehyde tester. Although the accuracy of small instruments may need to be improved, it is more telling than an empty time point. Who can guarantee that the formaldehyde content in the house will really be below the standard after two years?