[Methods to remove formaldehyde after decoration]

Formaldehyde is the most common volatile pollutant in modern interior renovation. However, most people's understanding of it is limited to the vague concepts of "pungent smell" and "carcinogenic." While formaldehyde is harmful to the human body, it is not a toxic gas; it only impacts health when inhaled in certain quantities or over long periods. According to safety standards established by global health and environmental protection agencies, indoor formaldehyde concentration should be below 0.08 ppm, while the European Union standard is below 0.1 ppm. Excess formaldehyde in indoor air can have adverse effects on human health. According to data from the U.S. National Cancer Institute, when indoor formaldehyde levels exceed 0.1 ppm, individuals sensitive to formaldehyde may experience burning sensations in the eyes, nose, and throat, which can further lead to coughing, asthma triggers, and skin irritation. It has an even more severe impact on pregnant women, potentially causing fetal deformities. The danger posed by formaldehyde should not be underestimated.

Formaldehyde concentration unit

Formaldehyde concentration is expressed in ppm. Ppm stands for "parts per million," defined as the number of parts per one million parts. 1 ppm is one-millionth. Using paint as an example, if one liter of paint contains one microliter (μL) of formaldehyde, the formaldehyde content is 1 ppm. Based on the aforementioned standards, to meet the definition of being harmless to the human body, the formaldehyde contained in ten liters of paint must be less than or equal to one microliter (μL).

Formaldehyde: An omnipresent existence

The chemical nature of formaldehyde

Formaldehyde (chemical formula HCHO) is the simplest aldehyde compound. It is a colorless gas at room temperature with a strong, pungent odor and is easily soluble in water. Due to its low molecular weight and high volatility, it can penetrate human cell membranes and cause deep-tissue damage.  

Industrial and daily life applications 

Due to its low cost and high reactivity, formaldehyde is widely used in:  

• Adhesive manufacturing: Used in wood panel adhesives and glue.
• Textile processing: Anti-wrinkle, anti-shrink, and flame retardant agents.
• Disinfection and preservation: Specimen preservation and sterilization of medical instruments.
• Personal care products: Preservatives in detergents and cosmetics.

Characteristics of formaldehyde release during renovation:

• Persistence: The release cycle of formaldehyde in wood panels can last from 3 to 15 years, with the first 3 months being the period of highest volatility.
• Impact of temperature and humidity: For every 1°C increase in temperature, the release rate increases by 12%-15%. When humidity exceeds 60%, the diffusion rate doubles. Even if low concentrations of formaldehyde (below 0.1 ppm) may have no obvious odor, they may have already exceeded safety standards.

Formaldehyde hazards: From acute irritation to cancer risk

Toxicological mechanisms

Formaldehyde is classified as a Group 1 carcinogen by the WHO. Its hazards stem from:  

• Protein denaturation: Binding with cellular enzymes to disrupt metabolic functions.
• DNA damage: Inducing gene mutations and increasing the risk of leukemia and nasopharyngeal cancer.
• Immune suppression: Reducing lymphocyte activity, triggering allergic asthma and hives.

Acute exposure (indoor formaldehyde levels of 0.1-1 ppm):  
Burning eyes, nose and throat pain, coughing; may induce fetal deformities in pregnant women.  

Chronic exposure (indoor formaldehyde levels above 0.08 ppm, sustained for 6 months):  
Memory loss, insomnia, anxiety, and developmental delays in children.  

Carcinogenic risk* (long-term indoor formaldehyde levels >0.12 ppm):  
U.S. NCI research indicates that occupational exposure increases the risk of sinonasal cancer by 74%.  

Formaldehyde-sensitive groups

• Infants and young children: Their breathing rate-to-body weight ratio is twice that of adults, making them more susceptible to damage.
• Pregnant women: Formaldehyde can cross the placental barrier, potentially leading to miscarriage or fetal deformities.
• People with allergies: Triggers asthma and atopic dermatitis.

Sources of formaldehyde in renovation

Apartments in Hong Kong have relatively small floor areas, making it difficult for formaldehyde to disperse into the air. Coupled with a humid and hot climate, the dangers of formaldehyde are easily exacerbated. Generally, what are the sources of formaldehyde following renovation projects in Hong Kong?

Rank 1: Panel furniture (approximately 60-70% of total)

• System furniture such as wardrobes, bookcases, and TV cabinets (often using "particle board," "fiberboard," and other panels containing urea-formaldehyde resin).
• Custom cabinetry (especially base panels in kitchen cabinets, as moisture accelerates formaldehyde release).

Rank 2: Flooring and wall materials (approximately 15-20% of total)

Composite wood flooring:  

• Multi-layer adhesive structure; base-layer adhesives contain formaldehyde.
• Hong Kong's humid climate easily causes floors to expand, accelerating the decomposition and release of glue.

Wallpaper and glue:  

• Wallpaper backing glue often contains formaldehyde.
• Inferior quality glue may be mixed with industrial adhesive to increase stickiness.

Rank 3: Coatings and paints (approximately 5-10% of total)

Inferior latex paint:  

• Formaldehyde is added as a preservative to extend shelf life (especially in budget interior wall paints).
• During renovations of some older buildings in Hong Kong, multiple layers are applied to cover mold spots.

Wood paint:  

• Solvent-based paints used for wooden doors and window frames have high initial release levels.

Rank 4: Soft furnishings and textiles

Blackout curtains:  

• Treated with formaldehyde resin for anti-wrinkle and anti-shrink properties.
• High-rise density in Hong Kong requires blackout fabrics, which increases the risk.

Carpets:  

• Backing glue and dyes may contain formaldehyde.

Rank 5: Materials for hidden works (approximately 3-5% of total)

Silicone sealant and grout:  

• Inferior acidic silicone sealants have high short-term release levels.
• Commonly found at bathroom countertops and window frame joints.

Soundproofing cotton and insulation materials:  

• Some foam-based materials contain formaldehyde.

Practical formaldehyde removal for a healthy home

Source control strategies (precautions before renovation):  

• Choose E0/ENF grade panels.
• Use formaldehyde-free adhesives such as MDI glue or soy-based glue.
• Use eco-friendly functional paints.

Material substitution alternatives:  

• Flooring: Choose low-formaldehyde materials such as SPC stone-plastic flooring / micro-cement.
• Walls: Choose low-formaldehyde materials such as SPC wall panels / micro-cement / functional paint.
• Furniture: Prioritize solid wood with mortise-and-tenon joints, avoiding finger-jointed boards.

Handling techniques during the volatility period:  

The "Golden Ventilation Rule":

• Ventilate for at least 3 months after renovation in summer, and 6 months in winter.
• Open windows daily between 10:00-16:00, using industrial fans placed diagonally to accelerate air exchange.
• Install a fresh air system to maintain an air exchange rate of >1.0 times/hour.

Temperature and humidity control:  

• Use a humidifier to control humidity between 50%-60% to promote formaldehyde release.

Formaldehyde purification technology:

Activated carbon adsorption -- Simple to operate but easily saturated; requires regular replacement. Estimated removal efficiency: 15%-30%.
Photocatalytic oxidation -- Long-term decomposition of pollutants; requires continuous UV light activation. Estimated removal efficiency: 50%-70%.
Biological enzyme decomposition -- Microorganisms metabolize formaldehyde; no secondary pollution to the environment. Estimated removal efficiency: 40%-60%.
Air purifier (HEPA + activated carbon filter) -- Can immediately lower concentrations, but addresses symptoms rather than root causes; involves consumable costs. Estimated removal efficiency: 60%-80%.
Professional fumigation treatment -- High-temperature steam penetrates and decomposes, quickly reducing short-term formaldehyde release. Estimated removal efficiency: 70%-90%.  

Misconceptions about formaldehyde purification technology:

Potted plants: To achieve theoretical results, 12 spider plants are required for every 1㎡ of space.
Peel masking method: Pomelo peels and tea leaves can only mask odors; they have no decomposition effect.
Ozone oxidation risk: High-concentration ozone itself is a primary pollutant and may damage lung function.  

Design House HK | Focusing on home health

In addition to providing professional interior design services, Design House HK cares about your home health. Regarding renovation materials, we use eco-friendly paints and SPC stone-plastic panels imported from Germany and Belgium, as well as partners providing micro-cement with French A+ environmental certification. For furniture, we select E0-grade panels to safeguard the home health of your children, the elderly, and pets. You are welcome to inquire about our interior design services at any time.