Organic Pollutants: Improving Indoor Air Quality

Indoor air quality is a significant concern for human health, especially as people in developed countries spend approximately 90% of their time indoors. The World Health Organization (WHO) has identified indoor air pollution as the world's largest single environmental health risk, with 3.2 million premature deaths annually attributed to illnesses caused by indoor cooking. This problem is particularly acute in developing countries, where three billion people are affected by indoor air pollution, mostly relating to cooking and heating methods that involve burning biomass fuel, such as wood, charcoal, dung, and crop residue, in poorly ventilated spaces. In addition, volatile organic compounds (VOCs), emitted as gases from solids or liquids, can be up to ten times more concentrated indoors than outdoors, with thousands of common household products contributing to this issue.

Volatile organic compounds (VOCs)

The EPA's Total Exposure Assessment Methodology (TEAM) Study found levels of about a dozen common organic pollutants to be 2 to 5 times higher inside homes than outdoors, regardless of location. Concentrations of many VOCs are consistently higher indoors (up to 10 times higher) than outdoors. This is due to the widespread use of organic chemicals as ingredients in household products.

Some immediate symptoms that people may experience after exposure to VOCs include irritation and illness. The ability of organic chemicals to cause health effects varies, with some being highly toxic and others having no known health impact. The extent and nature of the health effects depend on factors such as the level of exposure and the duration of exposure. Children, older people, and individuals with respiratory conditions are at the highest risk of experiencing health problems associated with VOCs.

To reduce exposure to VOCs, it is recommended to increase ventilation by opening doors and windows and using fans to maximise outdoor air circulation. It is also important to keep the temperature and relative humidity low as chemicals off-gas more in high temperatures and humidity. When using products containing VOCs, it is crucial to follow the instructions, wear proper personal protection like gloves and masks, and store them away from living spaces in well-ventilated areas. Additionally, opting for clean fuels, such as biogas, ethanol, LPG, natural gas, and electricity, can help reduce indoor air pollution caused by burning solid fuels.

Clean fuels

The burning of solid fuels, such as firewood, crop waste, and dung, releases dangerous particulate matter, carbon monoxide, and other toxic pollutants, leading to indoor air pollution levels that can be up to 20 times worse than the WHO's air quality guidelines. This is a major health risk, particularly for the world's poorest, and disproportionately impacts women and children, who spend the most time near the domestic hearth. The pollutants released by burning solid fuels include volatile organic compounds (VOCs), which are emitted as gases from certain solids or liquids and can have adverse health effects. VOCs are found in a wide array of household products, including paints, varnishes, cleaning products, and fuels, and can be released during use and storage.

To improve indoor air quality, the WHO recommends the use of clean fuels, such as biogas, ethanol, liquefied petroleum gas (LPG), natural gas, and electricity. Solar cookstoves can also be an important solution where conditions are suitable. These cleaner fuels and technologies reduce harmful emissions and personal exposure to household air pollutants, improving health outcomes and reducing the environmental impacts related to the demand for solid fuels.

Access to clean fuels is critical in reducing the health risks associated with indoor air pollution. As access to clean fuels and technologies increases, death rates from household air pollution begin to fall. Therefore, it is important for households to transition from traditional solid fuel sources to cleaner, more modern alternatives for cooking, heating, and lighting.

Indoor cooking

Cooking is an essential activity that everyone does inside their homes. However, indoor cooking can introduce various pollutants and chemicals into the indoor air, which can be harmful to human health. The World Health Organization (WHO) estimates that 3.2 million people die prematurely each year from illnesses attributed to indoor air pollution caused by indoor cooking, and this includes over 237,000 children under five.

The type and amount of emissions released during indoor cooking depend on the cooking source and methods used. For instance, frying and deep frying release a high amount of harmful emissions, as the oil emits polycyclic aromatic hydrocarbons (PAHs) when heated to high temperatures. PAHs can be harmful to eye and respiratory health. Gas stoves and ovens are also a major source of indoor air pollution, producing carbon monoxide, nitrogen oxides, formaldehyde, and small and ultrafine particulate matter. These pollutants can have severe health impacts, including lung irritation, worsening of asthma, and respiratory problems.

To reduce indoor air pollution from cooking, several measures can be implemented. Using electric stoves and ovens can help, as they generally emit a much smaller quantity of pollutants. Induction cooktops are another option, as they use a magnetic field to heat cookware directly, providing better temperature control and lessening the chance of accidental burns. Proper ventilation is also crucial, as it helps to quickly transfer pollutants out of the home. Installing a UL-listed carbon monoxide detector and an all-in-one indoor air quality monitoring device can help monitor pollutant levels. Cooking on the back burner, using lids to trap fumes, and avoiding high-temperature cooking methods like grilling and frying can also reduce emissions.

In addition to these measures, utilizing modern air purification technology can be beneficial. Some air purifiers can remove gases and odours while capturing up to 99.97% of pollutants as small as 0.3 microns. Furthermore, transitioning from traditional solid fuel sources such as firewood, crop waste, and dung to cleaner non-solid fuels like natural gas, ethanol, or electricity can significantly reduce indoor air pollution, especially in low-income households.

Poor ventilation

Indoor air pollution is caused by a range of human activities, from cooking and heating to the use of household products. In developing countries, the burning of solid fuel sources such as firewood, crop waste, and dung for cooking and heating is a major source of indoor air pollution. The WHO estimates that 3.2 million people die prematurely each year from illnesses attributed to indoor air pollution caused by indoor cooking, with 237,000 of these being children under five. As access to clean fuels and technologies increases, death rates from household air pollution decrease.

Inadequate ventilation can also lead to excessive moisture and high humidity, which can spur mold growth. This can be caused by poor construction or rehabilitation, site design that does not properly manage water, and/or inadequate air exchange. Mechanical ventilation systems, such as heating, ventilation, and air conditioning (HVAC) systems, can also contribute to indoor air quality problems if they are not properly maintained. These systems can become contaminated with mold, bacteria, or other pollutants, which are then circulated throughout indoor spaces.

Pollutants from indoor sources, such as chemicals used in construction or renovation, can accumulate to harmful levels if there is insufficient ventilation. Outdoor air pollutants can also be drawn indoors through open doors, windows, or ventilation systems.

To improve indoor air quality, it is important to ensure proper ventilation. This can be achieved through a combination of natural ventilation, such as opening windows and doors, and mechanical ventilation, such as fans and exhaust systems. Regular maintenance of ventilation systems is also crucial to prevent the spread of contaminants.

Sick building syndrome

The precise cause of SBS is unknown, but it is attributed to poor indoor air quality. Various factors contribute to SBS, including poor ventilation, poorly maintained air conditioning systems, and the use of new building materials that off-gas toxic fumes. Other possible causes include contaminants from outdoor sources, such as pollutants from vehicle exhaust, plumbing vents, and building exhausts, which can enter the building through openings and poorly located air intake vents.

The National Institute for Occupational Safety and Health (NIOSH) considers factors such as indoor combustion, the buildup of carbon monoxide and inhalable particles, and volatile organic compounds when assessing whether a building may be labelled a "sick building." Symptoms of SBS can include watering eyes, hoarseness, headaches, dry and itchy skin, dizziness, nausea, heart palpitations, miscarriages, shortness of breath, nosebleeds, chronic fatigue, mental fogginess, tremors, and swelling of the legs or ankles.

SBS can be challenging to diagnose due to the wide range of symptoms, which can also be caused by other conditions such as the common cold. However, if symptoms recur consistently in a particular building, SBS may be a potential cause. Diagnosing SBS involves ruling out other conditions and identifying specific symptoms and their triggers.

To reduce the risk of SBS, individuals can take breaks outside, open windows for fresh air (avoiding high pollen periods), and give their eyes a break from computer screens. Employers can also work with employees to identify and eliminate possible risk factors.

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