Indoor air pollution has been in the news in recent years, and it has become the most harmful invisible killer to public health. Studies have shown that 68% of current diseases are related to indoor air pollution. Formaldehyde has become a major pollutant in newly renovated homes in China. If you want to know about formaldehyde, just read this article.
What is formaldehyde
Formaldehyde is a gas that is easily soluble in water, alcohol and ether, and colorless with pungent odor. It is gaseous at room temperature, usually in the form of a 37% aqueous solution - formalin, which has a boiling point of 19 °C, so it is highly volatile at room temperature.
In recent years, there is a huge market demand for artificial panels and building decoration materials, and formaldehyde has the functions of strengthening the hardness, insect resistance and anti-corrosion of wood-based panels, making it widely used as an efficient and inexpensive adhesive.
Formaldehyde hazards
Studies have shown that formaldehyde is a highly toxic substance, and formaldehyde ranks second in the list of chemicals that are prioritized for control of toxic chemicals in the mainland. Formaldehyde has been identified by the World Health Organization as a carcinogenic and teratogenic substance, and is recognized as a source of allergies and one of the potential forced mutant substances.
The effects of formaldehyde on human health are mainly manifested in abnormal sense of smell, irritation, decreased allergic function, abnormal lung function, abnormal liver function and abnormal immune function.
Long-term exposure to low-dose formaldehyde can cause chronic respiratory diseases, causing nasopharyngeal cancer, colon cancer, brain tumors, menstrual disorders, and gene mutations in the cell nucleus; Causes pregnancy syndrome, neonatal chromosomal abnormalities, leukemia; Causes memory and mental decline in adolescents. Among the people who come into contact, children and pregnant women are particularly sensitive to formaldehyde and the harm is greater.
When its concentration reaches 0.06~0.07mg/m³ per cubic meter of air, children will experience slight wheezing. When the formaldehyde content in the air is 0.1mg/m³, there is a peculiar smell and discomfort; When it reaches 0.5mg/m³, it can irritate the eyes and cause tearing; Up to 0.6 mg/m³, it can cause throat discomfort or pain. At higher concentrations, it can cause nausea and vomiting, cough, chest tightness, wheezing and even pulmonary edema; When it reaches 30 mg/m³, it can cause immediate death.
The main source of indoor formaldehyde
1. Man-made panels
Formaldehyde has strong adhesion, and can strengthen the hardness, insect-proof, and anti-corrosion functions of wood-based panels, so it is widely used in man-made panels, such as plywood, blockboard, MDF, particleboard and laminate flooring used for interior decoration, so it is inevitable to release formaldehyde into the room.
2. Furniture
It mainly refers to the formaldehyde release in the furniture with wood-based panels as the main raw material and the adhesive used in the pasting of furniture finishes. In recent years, more and more home decoration is more rational, light decoration, heavy decoration concept has been accepted, so that individual furniture companies have no conscience, blind pursuit of profits, unqualified plate furniture everywhere, making furniture become a formaldehyde emission station.
3. Decorative materials
Various interior decoration materials, paints, coatings and foams have formaldehyde components. There are also some decorative textiles, such as bedding, wall coverings, wallpaper, sofa covers, curtains, fabric furniture, in order to strengthen wrinkle resistance, waterproof, fire resistance, some formaldehyde-containing additives will be added to textiles. Formaldehyde in insulating foams made of urea-formaldehyde resins in building materials also has the potential to be released.
Wherever adhesives are used in large quantities, formaldehyde is released. In short, if there are more decorative materials, furniture, and daily necessities that contain formaldehyde in the room, the greater the formaldehyde release, and of course, if the closed process is done well, it will reduce the release of formaldehyde. It is important to know that formaldehyde is a harmful substance with a long release cycle, and the slow release time can reach 3~15 years.
How to remove formaldehyde after decoration
The first type: ventilation
Ventilation is the use of fresh air circulation to remove formaldehyde accumulated in the living room. Regular ventilation can indeed have an effect on formaldehyde in the newly renovated house, but this method is only suitable for indoor free formaldehyde emissions, and it is not a cure.
The second type: temperature and humidity control method
Studies have shown that the amount of formaldehyde released increases with the increase of temperature and humidity. Therefore, in daily life, the indoor temperature and humidity can be adjusted by air conditioning to regulate formaldehyde emissions and avoid excessive accumulation.
● When the temperature is high in summer, the indoor formaldehyde emissions will be much higher than in other seasons. In this season, you don't need to turn on the air conditioner, just keep the windows open for ventilation;
● In spring and autumn, you can turn the air conditioner to heating mode, turn on the air conditioner at night and close the windows, and open the windows for ventilation during the day;
● In winter, when the weather is cold, it is necessary to heat up, generally turn on the heating or air conditioning at night to keep the indoor temperature higher than 19.5 degrees Celsius.
The third type: physical adsorption method
The so-called physical adsorption is a method of using adsorption materials to adsorb formaldehyde to remove formaldehyde exhaust gas. The commonly used method of activated carbon is simple and easy, but the adsorbent needs to be replaced regularly, and with the extension of time, formaldehyde is very likely to be re-released from the adsorbent, forming secondary pollution.
Fourth: chemical removal method
It is a method of chemical reaction with formaldehyde through chemical reagents to convert it into other substances and degrade it. For example, the photocatalyst spray on the market belongs to the chemical aldehyde removal method. This method can harmlessly decompose formaldehyde and will not cause secondary pollution to furniture.
TIP: In general, after the decoration of the new house, don't rush to move in, although some methods can indeed degrade formaldehyde, but it can only be used as an auxiliary means, and can not be completely treated with formaldehyde.
As mentioned earlier, the slow release time of formaldehyde can reach 3~15 years, so it is impossible to be completely removed. The amount of formaldehyde released does not exceed the standard and does not affect human health.
Is photocatalyst useful in removing formaldehyde?
Under the irradiation of ultraviolet light, the photocatalyst will produce a photocatalytic reaction similar to photosynthesis, producing free hydroxide groups and reactive oxygen species with strong oxidation ability, which has strong photoredox function, can oxidize and decompose various organic compounds and some inorganic substances, can destroy the cell membrane of bacteria and solidify the protein of the virus, and can kill bacteria and decompose organic pollutants. It has strong sterilization, deodorization, mildew-proof, anti-fouling and self-cleaning, and air purification functions. Photocatalysts have a good degradation and killing effect on unstable compounds of medium and low molecular weights and most of the germs, including formaldehyde.
The new generation of photocatalyst imported from Japan has overcome the problem of traditional photocatalyst, which requires strong ultraviolet light to decompose formaldehyde, and can also decompose formaldehyde 24 hours a day under visible light conditions.