Formaldehyde is a colorless, irritating and water soluble gases. It has a role in the coagulation of proteins, which 35% to 40% aqueous solution known as formalin, often impregnated with a solution as specimens. Formaldehyde is more toxic substances, toxic chemicals in our priority control formaldehyde ranked second on the list.

Formaldehyde in the indoor environment can be divided into two categories from the source point of view:

1, from outdoor air pollution:

Industrial emissions, car exhaust, smog and other emissions to some extent or may produce a certain amount of formaldehyde, but few in this part of the content. According to the reports indicate that the annual mean concentration of formaldehyde in urban air is about 0.005 ~ 0.01mg / m3, usually not more than 0.03mg / m3, this part of the gas for some time to enter the room, it is a source of indoor formaldehyde pollution constitution.

2, from indoor pollution itself:

Mainly in building materials, decoration materials and daily necessities and other chemical products for indoor use mainly, but also including fuel and incomplete combustion of tobacco and some other secondary factors.

Formaldehyde has a strong adhesion, hardness and simultaneously enhance pest control, corrosion resistance plate, so now on the market a variety of particleboard, medium density fiberboard, plywood in both the use of formaldehyde as the main component of urea-formaldehyde resin as a binder therefore inevitably contain formaldehyde. Also new furniture, walls, floors decoration auxiliary equipment have to use an adhesive, so all helpful to the adhesive where there is always a release formaldehyde gas, indoor environmental hazards. Because of urea from urea-formaldehyde resin - formaldehyde resin foam insulation material has good thermal insulation effect, it is often made of the building envelope so that the indoor temperature is not outside influence. Further formaldehyde may come from cosmetics, detergents, pesticides, disinfectants, preservatives, printing inks, paper and the like.

Thus, generally speaking formaldehyde source of indoor environment is very broad, and its formaldehyde content generally newly renovated house up to 0.40mg / m3, the individual is likely to reach 1.50mg / m3. The study showed that the formaldehyde content in indoor environments and houses of use, temperature, humidity and ventilation of houses are closely related. In general, the longer the use of housing, the less the residual amount of formaldehyde in the indoor environment; the higher the temperature, the greater the humidity, the better the release of formaldehyde; better ventilation, release construction, decoration materials in formaldehyde correspondingly faster, more conducive to clean indoor environment.

3, distributed approach formaldehyde

1), the timber itself exudes a very small amount of formaldehyde at a temperature and humidity effects.

2), urea-formaldehyde resin glue residue inevitably part of the process of free formaldehyde outward distribution.

3), plywood during the curing process, the linear part of the resin is not formed into a net-like structure so that the decomposition of formaldehyde to the outside world for distributing free form.

4), formed by the decomposition of free formaldehyde radiated from the partially cured resin is not completely under the action of heat and moisture.

Measured data shows that under normal circumstances renovation, interior decoration five months later, the concentration of formaldehyde may be less than 0.1 mg / cubic meter; 7 months after renovation can be reduced to 0.08 mg / cubic meter. Japanese studies have shown that indoor formaldehyde release period is usually 3-15 years.