The Hidden Perils Within Your Home
As temperatures drop and the cold front hits, many people shut their windows and doors to keep out the chill, take long hot showers to warm up, or enjoy hotpot at home to ward off the cold. However, these activities—if not done with care—can lead to a sharp increase in indoor air pollutants, which in severe cases could even be fatal!
When we think of "air pollution", most people immediately picture outdoor air pollution caused by vehicle emissions or power plants. In reality, most of us spend more time indoors than outdoors, yet we pay less attention to indoor air pollution than outdoor air pollution. Many even believe that the outdoor air quality is worse and thus keep the windows shut. This can actually result in poor ventilation indoors, preventing the dilution of indoor air pollutants and creating an indoor air pollution problem.
In Hong Kong, most of the air pollutants at home can be categorised into three main types: combustion by-products, volatile organic compounds, and biological contaminants:
Combustion by-products
Activities like cooking with open flames, using non-compliant gas water heaters, and smoking indoors release nitrogen oxides and carbon monoxide. These pollutants not only irritate the respiratory system but are also harmful to human health. Excessively high concentrations of carbon monoxide can even be fatal due to suffocation. In early 2024, there were several incidents in Hong Kong where the use of non-compliant gas water heaters and cooking stoves led to the accumulation of carbon monoxide indoors, causing people to lose consciousness.
To prevent indoor pollution from combustion by-products, the first step is to avoid smoking indoors. When cooking with open flames or using gas water heaters, be sure to turn on the exhaust fans or open the windows to ensure proper ventilation. It is also important to note that air purifiers are not effective in removing these tiny pollutants. The best solution is still to maintain good indoor air ventilation.
Volatile organic compounds (VOCs)
Paint, dry cleaning solvents, and aerosol products (such as insecticides and hairsprays) release volatile organic compounds that easily evaporate at room temperature, including alkanes, arenes, and aldehydes. Among these, formaldehyde has been classified as a Group 1 carcinogen. Even compounds with lower toxicity can irritate the eyes and respiratory system, causing headaches, dizziness, and even vision impairment.
To reduce the impact of volatile organic compounds, it is important to ensure proper ventilation when using such products. You can also choose alternative products such as low-formaldehyde paint and furniture, and non-aerosol insecticides and personal care products.
Biological contaminants
Bacteria, fungi, and viruses are the three main types of indoor biological contaminants. Warm and humid weather, combined with inadequate ventilation, promotes the growth of bacteria and fungi. When they multiply in large numbers, they can produce unpleasant odours and trigger allergies or asthma, or even cause direct illness.
To prevent the growth of biological contaminants, it is important to ensure not only proper ventilation but also maintain dryness and cleanliness. This includes regularly cleaning air conditioner filters, frequently wiping down furniture, and cleaning floors. Dust and organic matter are food for bacteria and fungi, so frequent cleaning reduces their food source, helping to curb their growth and improve indoor air quality.