Formaldehyde poisoning is primarily caused by furniture, rather than decoration materials. Furniture, especially those made from particleboard, plywood, and medium-density fiberboard (MDF), often contains high levels of formaldehyde. This is due to the use of adhesives in the manufacturing process, which release formaldehyde gas over time. According to the U.S. Environmental Protection Agency (EPA), formaldehyde is a known carcinogen and can cause a range of health issues, including respiratory irritation, allergic reactions, and in severe cases, cancer.

The reason furniture is a significant source of formaldehyde poisoning lies in the manufacturing process. Particleboard, plywood, and MDF are made by combining wood fibers with formaldehyde-based adhesives. These adhesives are used to bind the wood particles together, creating a solid piece of furniture. Over time, these adhesives can break down, releasing formaldehyde gas into the air. This process is known as off-gassing and can continue for years after the furniture is purchased.

Data from the EPA indicates that indoor levels of formaldehyde can be up to 10 times higher than outdoor levels, primarily due to furniture and other building materials. A study published in the Journal of Environmental Health Perspectives found that new furniture can release formaldehyde at levels that exceed the EPA's recommended limits for indoor air quality. For example, a study conducted by the University of California, Berkeley, found that new particleboard furniture could release formaldehyde at levels as high as 0.3 parts per million (ppm), which is above the EPA's recommended limit of 0.1 ppm for long-term exposure.

In addition to furniture, other sources of formaldehyde in the home can include building materials, such as insulation and carpeting, as well as household products like air fresheners and cleaning agents. However, furniture remains a primary source of formaldehyde exposure due to its widespread use and the significant amounts of formaldehyde it can release.

To mitigate the risk of formaldehyde poisoning, consumers should look for furniture labeled as low-emitting or formaldehyde-free. Additionally, maintaining good ventilation in the home can help reduce the levels of formaldehyde in the air. It is also important to be aware of the potential health risks associated with formaldehyde exposure and to take appropriate precautions to minimize exposure.