Air Quality Alert: Indoor Pollution Sources Revealed

Indoor air pollution is a serious environmental hazard that affects people's health and well-being. It is caused by a variety of factors, including human activities such as smoking, burning solid fuels, cooking, and cleaning. Indoor air pollution can also be caused by biological contaminants like mould, viruses, or allergens, and chemicals from building and construction materials, equipment, and furniture. Inadequate ventilation, high temperatures, and humidity levels can increase indoor pollutant concentrations. Outdoor air pollution can also penetrate indoors, and certain climatic conditions can increase the potential for indoor moisture and mould growth. According to the World Health Organization, indoor air pollution leads to approximately 3.2 million deaths globally each year, with developing countries being particularly affected due to the indoor burning of solid fuels like wood, coal, and dung.

Burning solid fuels, cooking, and cleaning

Cooking, especially at high temperatures, can also produce significant indoor air pollutants. Frying, deep-frying, grilling, and roasting release high levels of particulate matter (PM) and other harmful pollutants. The type of stove and cooking appliance used also influence the amount and type of pollutants released. Gas stoves, for instance, emit higher levels of nitrogen oxide (NOx) compared to other cooking methods. Electric stoves are generally cleaner but still require proper ventilation to minimise indoor air pollution.

The chemicals in cleaning products can also contribute to indoor air pollution. These products release toxic fumes made up of VOCs, which can cause various short- and long-term health issues when inhaled, including respiratory infections, asthma, and even cancer. Vacuuming can increase indoor air pollution unless suitable filters are used to trap pollutants. Mould, often found in damp and humid environments, is another indoor air pollutant that can trigger respiratory issues and exacerbate existing conditions like asthma.

Overall, the indoor air pollution caused by burning solid fuels, cooking, and cleaning can have significant health impacts. Ensuring proper ventilation and adopting cleaner technologies and fuels can help mitigate these issues and improve indoor air quality.

Poor ventilation

There are several ways outdoor air can enter and leave a building: infiltration, natural ventilation, and mechanical ventilation. Infiltration occurs when outdoor air flows into buildings through openings, joints, and cracks in walls, floors, and ceilings, and around windows and doors. Natural ventilation occurs when air moves through open windows and doors due to temperature differences between indoors and outdoors and wind. Mechanical ventilation devices include outdoor-vented fans that intermittently remove air from a single room, such as bathrooms and kitchens.

Mechanical ventilation systems in large buildings are designed not only to heat and cool the air but also to draw in and circulate outdoor air. However, if they are poorly designed, operated, or maintained, ventilation systems can contribute to indoor air problems. For example, in an effort to save energy, ventilation systems may not bring in adequate amounts of outdoor air.

Pollutants from indoor sources can accumulate to harmful levels if there is not enough outdoor air to dilute them. High indoor pollutant levels can be caused by inadequate ventilation, which does not carry indoor air pollutants out of the area. High temperature and humidity levels can also increase concentrations of some pollutants.

There are several signs that can indicate poor ventilation in a home, including moisture condensation on windows or walls, smelly or stuffy air, dirty central heating and air cooling equipment, and areas where items become moldy.

Outdoor air pollutants

Outdoor air pollution is primarily caused by emissions from various sources, including factories, fossil fuels, cars, and other sources depending on the area. Natural sources such as fossil fuel combustion and agricultural activities also contribute to outdoor air pollution. The predominant global source of outdoor pollution is fossil fuel burning, which includes natural gas combustion, contributing to outdoor air pollution when vented directly outside. Actions to reduce outdoor air pollution from natural gas combustion include reducing emissions from existing infrastructure and limiting new development and installations.

The relative importance of any single source of outdoor air pollution depends on the amount of pollutant emitted and the hazard posed by those emissions. For example, the average concentration of nitrogen oxides in buildings without combustion activities is half that of outdoor levels, but when gas stoves and heaters are used, indoor levels often exceed outdoor levels. Outdoor air pollution has short-term effects, such as allergic reactions, and long-term health effects, including an increased risk of cardiovascular and respiratory disease.

Outdoor air can enter buildings through infiltration, natural ventilation, and mechanical ventilation. Infiltration occurs when outdoor air flows into buildings through openings, joints, and cracks in walls, floors, and ceilings, and around windows and doors. Natural ventilation occurs through opened windows and doors, with air movement caused by temperature differences and wind. Mechanical ventilation uses specialized equipment to control airflow.

Reducing outdoor air pollution levels can be achieved by lessening fossil fuel combustion. Additionally, improving indoor air quality can help reduce outdoor pollutant concentrations.

Tobacco smoke

ETS is a well-known cause of illness and premature death. It is linked to lung cancer, cardiovascular disease, reproductive issues, and other diseases. It can also cause health problems in infants and children, including sudden infant death syndrome, respiratory infections, ear infections, and more frequent and severe asthma attacks. There is no known safe level of exposure to secondhand tobacco smoke.

The Tobacco Smoke Particles and Indoor Air Quality Study (ToPIQ) aims to assess the particle concentrations produced by different tobacco products under various conditions. The study will use a self-made ETS emitter (ETSE) to generate ETS indoors while collecting data on the concentration of particulate matter through laser aerosol spectrometry.

Secondhand tobacco smoke can move between rooms and buildings, including between apartment units. While ventilation, filtration, and air cleaning techniques can reduce secondhand smoke, they do not eliminate it. The concentration of pollutants in indoor smoking areas, such as cafes, can be significantly higher than in outdoor areas. The number of smokers and the type of tobacco used are influential factors in the generation of indoor pollutants.

Building materials

People tend to spend approximately 90% of their time indoors, so indoor air quality has a significant influence on human health and productivity. The energy crisis of the 1970s led to a shift towards more airtight and insulated buildings, which reduced the circulation of fresh air in air conditioning systems. This, combined with the increased use of synthetic materials and chemicals in indoor construction and decoration, has contributed to indoor air pollution.

Older building materials can also release indoor air pollutants when disturbed or removed. For example, older homes may contain lead paint or asbestos, which can release dangerous chemicals into the air when disturbed. Additionally, tiles, insulation, or drywall may contain asbestos, and drywall installed in homes along the Gulf Coast states and Virginia between 2001 and 2009, often referred to as "Chinese drywall," has been found to give off high levels of hydrogen sulfide.

To improve indoor air quality, it is recommended to use sustainable, non-toxic, and air-purifying building materials that limit the off-gassing of pollutants. Good ventilation levels, with appropriate filtration, are also crucial for clearing indoor pollutants and preventing negative health impacts. Energy-efficient filtration appliances are recommended to reduce emissions and operating costs. Building certification systems like LEED and WELL give points for improving indoor air quality and using low-VOC construction materials.

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