Particulate Matter: Indoor-Outdoor Air Pollution Culprit

Particulate matter, often written as PM, is a complex mixture of solid and/or liquid particles suspended in the air. These particles vary in size, shape, and composition, and can be found both outdoors and indoors. Outdoor PM can enter buildings through windows, doors, ventilation systems, and small cracks, becoming indoor PM. Indoor PM can also be generated through human activities such as cooking, smoking, burning candles, and using fireplaces. PM2.5, fine particulate matter with a diameter of 2.5 microns or less, is of particular concern as it can be inhaled into the deepest parts of the lungs, causing serious adverse health effects.

Outdoor PM2.5 sources include vehicle exhaust, burning wood, and wildfires

Particulate matter, or PM, is a mixture of solid particles and liquid droplets found in the air. It can be categorised based on size, with larger particulate matter called PM10 and much finer particulate matter called PM2.5. PM2.5 is the most harmful to human health.

PM2.5 is composed of inorganic ions, carbonaceous compounds (including black and organic carbon), and mineral dust. Outdoor sources of PM2.5 include vehicle exhaust, burning wood, and wildfires. Vehicle exhaust, for instance, releases pollutants such as nitrogen oxides and sulfur dioxide, which contribute to the formation of PM2.5.

Vehicle exhaust is a significant source of outdoor PM2.5. Motor vehicles, including on-road and off-road vehicles, emit pollutants such as nitrogen oxides (NOx) and sulfur dioxide (SO2) into the atmosphere. These gases then undergo complex reactions to form secondary particles, which make up a large portion of PM2.5. Residential energy use, energy generation, industrial processes, and agricultural activities also contribute to outdoor PM2.5 through the emission of similar gaseous precursors.

Burning wood and other fuels, such as gasoline, oil, and diesel, are another major source of outdoor PM2.5. The combustion of these fuels releases a variety of particles and chemicals into the air, including inorganic ions, metallic compounds, elemental carbon, and organic compounds. Wildfires, deforestation, and agricultural waste burning also contribute significantly to the outdoor PM2.5 mass. These activities release a large number of particles and pollutants into the atmosphere, which can have serious health implications.

The health effects of long-term exposure to PM2.5 are well-established. It has been linked to premature death, particularly in individuals with chronic heart or lung diseases. Additionally, reduced lung function growth in children and adverse effects in older adults with heart or lung conditions have been observed. The impact of PM2.5 on ecosystems, including plants, soil, and water, is also significant, as it affects light absorption and scattering in the atmosphere, leading to reduced visibility.

Indoor PM2.5 sources include cooking, tobacco smoking, and burning candles

Particulate matter, often written as PM, is a mixture of solid and/or liquid particles suspended in the air. These particles vary in size, shape, and chemical composition. PM10 refers to larger particulate matter, while PM2.5 refers to much finer particulate matter that is more harmful to health.

PM2.5 is associated with the greatest proportion of adverse health effects related to air pollution, both in the United States and worldwide. Short-term exposures to PM2.5 have been linked to the worsening of respiratory diseases, while long-term exposure can lead to premature death, particularly in individuals with chronic heart or lung diseases.

It is important to note that indoor PM2.5 levels can be mitigated through various approaches, including kitchen exhaust ventilation, indoor pollutant source reduction, and filtration of ventilation air. Additionally, good ventilation and prevention actions can help reduce the risk of respiratory viruses, including COVID-19.

PM2.5 can cause serious health issues, including lung and heart problems

Particulate matter, often written as PM, is a mixture of solid and liquid particles suspended in the air. PM2.5 refers to fine particulate matter with a diameter of 2.5 microns or less. These particles are so small that they can be inhaled and travel deep into the lungs, reaching the alveoli, or air sacs. Once in the alveoli, PM2.5 particles can irritate and damage the alveoli walls, causing serious health issues, including lung and heart problems.

PM2.5 is the main component of particle pollution, which is a mixture of solids and aerosols composed of small droplets of liquid, dry solid fragments, and solid cores with liquid coatings. These particles can contain inorganic ions, metallic compounds, elemental carbon, organic compounds, and compounds from the earth's crust. Due to their small size, PM2.5 particles can be carried over long distances by wind and then settle on the ground or water, where they can be harmful to both the environment and human health.

The health risks associated with PM2.5 exposure are well-established. Short-term exposure to PM2.5 has been linked to increased hospital admissions for heart or lung causes, acute and chronic bronchitis, asthma attacks, emergency room visits, respiratory symptoms, and restricted activity days. Long-term exposure to PM2.5 has been associated with even more severe health issues, including premature death, particularly in people with chronic heart or lung diseases, and reduced lung function growth in children. Research has also shown that children living in communities with high levels of PM2.5 have smaller lungs at age 18 compared to those living in areas with lower PM2.5 levels.

Both outdoor and indoor sources contribute to PM2.5 pollution. Outdoor sources include vehicle exhaust, emissions from the combustion of gasoline, oil, diesel fuel, or wood, and industrial activities. Indoor sources of PM2.5 include cooking, smoking, burning candles or incense, using fireplaces or fuel-burning space heaters, and household products such as cleaning agents and air fresheners. It's important to note that indoor PM levels can exceed outdoor levels, and improving indoor air quality is crucial to reducing the health risks associated with PM2.5 exposure.

PM10 is larger than PM2.5 and can induce adverse health effects when inhaled

Particulate matter, often written as PM, is a mixture of solids, aerosols, and liquid droplets that vary in size, shape, and chemical composition. PM10 refers to particulate matter with a diameter of 10 microns or less, while PM2.5 refers to fine particulate matter with a diameter of 2.5 microns or less. As PM2.5 is smaller, it is a subset of PM10.

PM10 is larger than PM2.5 and can be inhaled, reaching the upper region of the lung and depositing on the surfaces of the larger airways. Inhalation of PM10 can induce adverse health effects, particularly for those with pre-existing respiratory conditions. Short-term exposure to PM10 has been linked to the worsening of respiratory diseases, including asthma and chronic obstructive pulmonary disease (COPD), leading to hospitalisations and emergency department visits. Long-term exposure to PM10 has been suggested by several studies to be associated with respiratory mortality.

PM2.5, being smaller in size, can penetrate deeper into the lungs, reaching the alveoli in the lower region of the lung. These particles can irritate and damage the alveoli walls, causing lung disease. Short-term exposure to PM2.5 has been associated with premature mortality, increased hospital admissions for heart and lung issues, acute and chronic bronchitis, asthma attacks, and restricted activity days. Long-term exposure to PM2.5 has been linked to reduced lung function growth in children and premature death, particularly in individuals with chronic heart or lung diseases.

Both PM10 and PM2.5 can originate from both indoor and outdoor sources. Outdoor particulate matter can enter buildings through openings, ventilation systems, and small crevices, while indoor sources include cooking, combustion activities, smoking, and biological sources such as mould spores and dust mites.

While PM2.5 is generally recognised as being more harmful to health due to its smaller size and ability to penetrate deeper into the lungs, PM10 still poses significant health risks, particularly to vulnerable individuals with respiratory conditions. Reducing exposure to both types of particulate matter is important to mitigate adverse health effects.

Actions to reduce indoor PM include improving ventilation and filtration

Particulate matter (PM) is a complex mixture of solid and/or liquid particles suspended in the air. It is categorised based on size, with larger particulate matter called PM10 and finer particulate matter called PM2.5. PM2.5 is the most harmful to health, as it can enter the lungs and travel to the air sacs (alveoli), irritating and corroding the alveoli wall and causing lung disease. Outdoor air pollutants, such as vehicle exhaust, wildfire smoke, and factory emissions, can enter buildings through windows, doors, ventilation systems, and small openings.

Indoor PM levels are influenced by outdoor levels, infiltration, ventilation, filtration systems, indoor sources, and occupant activities. To reduce indoor PM, it is essential to improve ventilation and filtration. Here are some actions to achieve this:

Improving Ventilation

• Increase fresh air circulation: Open windows or use exhaust fans to bring in outdoor air and remove indoor pollutants. When cooking or using fireplaces, ensure proper ventilation by using exhaust fans vented to the outside. Avoid using unvented stoves, fireplaces, or space heaters.
• Maintain HVAC systems: Regularly clean and maintain heating, ventilation, and air conditioning (HVAC) systems, including replacing air filters. This prevents the circulation of particulate matter and improves overall indoor air quality.
• Use proper venting for combustion appliances: Vent all fuel-fired combustion appliances, such as stoves, heaters, and furnaces, to the outdoors. Choose wood-burning stoves that meet EPA emission standards and ensure tight-fitting doors to minimise indoor particulate matter.

Enhancing Filtration

• Upgrade air filters: Install high-efficiency particulate air (HEPA) filters or upgrade furnace filters to a higher Minimum Efficiency Reporting Values (MERV) rating, preferably 13 or higher, to effectively capture and remove particulate matter from indoor air.
• Utilise air purifiers: Invest in portable air purifiers with HEPA filters to capture and remove particulate matter. These can be particularly useful in rooms with poor ventilation or high pollutant levels.
• Incorporate air-purifying plants: Consider adding indoor plants, such as spider plants or peace lilies, which have air-purifying properties and can help filter the air naturally.
• Control humidity: Maintain optimal humidity levels to prevent the growth of mould and mildew, which can release particulate matter into the indoor environment.

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