How Indoor Air Quality Is Affected By Materials

Indoor air pollution is a serious health threat, causing millions of deaths each year. Indoor air quality is often two to five times worse than outdoor air quality. Common indoor air pollutants include excessive moisture, volatile organic compounds (VOCs), combustion products, radon, pesticides, dust particles, viruses, and bacteria. These pollutants can cause or worsen respiratory diseases, lung cancer, and chronic lung conditions such as asthma. They can also lead to infections and other serious lung and respiratory problems. Indoor air pollution is caused by various sources, including human activities, building materials, furnishings, and outdoor air pollutants that find their way indoors. Understanding and addressing these sources are crucial for improving indoor air quality and protecting human health.

Volatile organic compounds (VOCs)

VOCs include a range of evaporated substances, such as formaldehyde, benzene, and toluene, which can be harmful to human health. Some VOCs are known or suspected to cause cancer in humans, and they can also irritate the eyes, nose, and throat, cause difficulty breathing and nausea, and damage the central nervous system and other organs. Long-term exposure to VOCs can damage the liver and kidneys. Concentrations of VOCs are typically higher indoors than outdoors, and they can be up to ten times higher inside homes.

To reduce exposure to VOCs, it is recommended to read product labels, avoid or limit the use of products with harmful ingredients, safely dispose of unwanted products, and increase ventilation when using products containing VOCs. It is also advisable to let new carpets or building products air outside before installing them and to avoid storing products with VOCs indoors. Keeping buildings smoke-free is important, as tobacco smoke contains VOCs and other carcinogens.

While there are no federally enforceable standards for VOCs in non-industrial settings, organizations such as the Lawrence Berkeley National Laboratory and the American Lung Association provide guidelines and resources for reducing exposure and improving indoor air quality.

Building materials and furnishings

The air inside a building can contain 100 to 1000 times more phthalates than outdoor air. Building materials and furnishings are a significant source of indoor air pollution, releasing gases and particles that can endanger health.

Many modern building materials have made construction faster and cheaper, but they have also introduced pollutants into indoor air. Building materials often emit volatile organic compounds (VOCs), which can cause a range of health problems, from respiratory irritation to headaches and even cancer. These VOCs are present in pressed wood products, such as plywood, particleboard, and medium-density fiberboard, which may contain urea-formaldehyde. Formaldehyde is a known carcinogen, causing skin, eye, nose, and throat irritation. Other sources of VOCs include paints, adhesives, solvents, polishes, and cleaning products, which can also emit formaldehyde, benzene, and other toxic chemicals.

Older building materials can also be problematic. Tiles, insulation, or drywall may contain asbestos, and homes built before 1978 are likely to contain lead paint. Disturbing these materials during remodelling or demolition can release dangerous chemicals and dust.

Carpets and rugs are another common source of indoor air pollution. They can off-gas, releasing 4-PCH, styrene, and formaldehyde. Carpets are also prime sources of dust, dirt, pollen, and mould spores, trapping additional pollutants if not maintained properly. Adhesives used for flooring installation can introduce high levels of VOCs and semi-volatile organic compounds (SVOCs). Caulking, grouts, and mortars may contain plasticizers, which can emit VOCs.

To mitigate these issues, it is recommended to air out building materials and carpets for at least 72 hours before installation, maintain good ventilation during use, and follow manufacturer advice. When choosing paints and flooring, opt for low-VOC options.

Tobacco smoke

ETS contains numerous toxic substances, including 69 carcinogens, 11 of which are known human carcinogens. These harmful components include particulate matter (PM), carbon monoxide (CO), nitrogen oxides (NOx), volatile organic compounds (VOCs), volatile aldehydes (e.g. formaldehyde), polyaromatic hydrocarbons (PAHs), nicotine, phenol, and furans. The concentration of these pollutants can be significantly higher indoors, especially in enclosed spaces like waterpipe cafes, where the air quality is diminished by large amounts of pollutants.

The adverse health effects of ETS are profound and well-established. Exposure to ETS has been linked to an increased incidence of lung cancer, cardiovascular diseases, and respiratory issues such as bronchitis and asthma. It can also cause or worsen lung diseases, trigger asthma attacks in children, and lead to reproductive issues and other diseases. There is no known safe level of exposure to secondhand tobacco smoke.

The indoor concentration of ETS can be reduced through ventilation, filtration, and air cleaning techniques, but these methods do not eliminate it entirely. The movement of ETS between rooms and apartment units further complicates its containment. Given the serious health risks associated with ETS exposure, it poses a substantial public health threat, especially considering the high percentage of people regularly exposed to it.

Poor ventilation

The air exchange rate is the rate at which outdoor air replaces indoor air. When there is little infiltration, natural ventilation, or mechanical ventilation, the air exchange rate is low and pollutant levels can increase. Outdoor air can enter a building by 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. Air movement associated with infiltration and natural ventilation is caused by air temperature differences and wind. Mechanical ventilation devices can include outdoor-vented fans that intermittently remove air from a single room, such as bathrooms and kitchens.

High temperature and humidity levels can also increase concentrations of some pollutants. In buildings, the typical sources for indoor emissions of biological contaminants include cooling towers, humidification systems, filters, drain pans, wet surfaces, and water-damaged building materials. Common biological contaminants include bacteria, viruses, dust mites, and cockroaches, which thrive in environments with excess moisture.

There are many sources of indoor air pollution, including combustion sources such as oil, gas, kerosene, coal, wood, and tobacco products; building materials and furnishings; and human activities, such as cooking, cleaning, and operating equipment. Signs that your home may not have enough ventilation include 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 a pressing issue that affects the health of people worldwide, especially children, older adults, and those with asthma. According to the World Health Organization, a staggering 90% of the global population breathes unsafe air. This poses significant risks to human health, with vulnerable groups being the most susceptible to adverse effects. Here is an overview of common outdoor air pollutants and their sources:

Nitrogen Oxides

Nitrogen oxides are a group of highly reactive and odorless gases that contribute to the formation of particulate matter (PM) and ozone in the atmosphere. Major sources of nitrogen oxides include vehicles, power plants, and other forms of fuel burning. When inhaled, these gases can lead to serious health issues, especially for vulnerable populations.

Carbon Monoxide

Carbon monoxide is a colorless, odorless, and highly toxic gas that poses significant dangers to human health. It is primarily released into the atmosphere through the burning of fossil fuels, such as diesel and gasoline, by vehicles and heavy machinery. Exposure to carbon monoxide can have detrimental effects on human health, even at low concentrations.

Sulfur Oxides

Sulfur oxides, including sulfur dioxide, are highly reactive gases released from burning diesel fuel. These gases contribute to the formation of particulate matter and smog in the atmosphere. Inhalation of sulfur oxides can lead to respiratory issues and other adverse health effects, especially when present in high concentrations.

Particulate Matter (PM)

Particulate matter refers to the mixture of solid particles and liquid droplets present in the air. Urban environments, such as construction sites, smokestacks, fires, and unpaved roads, emit coarser particles like windblown dust, dirt, smoke, and soot. Due to their small size, these particles can linger in the air for extended periods, eventually finding their way into the human body. Prolonged exposure to particulate matter can cause pulmonary inflammation, decreased lung function, and exacerbate respiratory conditions such as asthma.

Ozone

Ground-level ozone, often referred to as "bad ozone," is a harmful pollutant created through chemical reactions between man-made volatile organic compounds (VOCs) and nitrogen oxides in the presence of sunlight. Ozone, along with particulate matter, is one of the most common air pollutants that exceed federal health-based standards in the United States. Elevated levels of ozone can cause pulmonary inflammation, decreased lung function, and worsen asthma symptoms.

It is important to recognize that outdoor air pollutants can easily enter indoor spaces through open doors and windows, cracks in foundations, and even on our clothing and shoes. Taking proactive measures, such as limiting time spent outdoors when pollution levels are high and improving indoor ventilation, can help reduce exposure to these harmful pollutants.

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