Particulate Pollutants: Harmful Impacts On Human Health

Fine particulate matter (PM2.5) poses the greatest risk to human health. These particles are 2.5 micrometres or less in diameter and are so small that they can be inhaled, entering deep into the respiratory tract and reaching the lungs. Long-term exposure to PM2.5 has been linked to an increased risk of heart disease, respiratory diseases, lung cancer, and even premature death. Sources of PM2.5 include combustion of fuels, vehicle exhaust, burning wood, and industrial activities. While air quality has improved over the years, certain vulnerable populations, such as people of colour and those living near emission sources, remain at higher risk from the health impacts of particulate matter pollution.

Particulate matter (PM) and its health risks

Particulate matter (PM) refers to a mix of tiny solid and liquid particles that are in the air we breathe. It is not a single pollutant but a mixture of many chemical species. These particles vary widely in size, shape, and chemical composition and may contain inorganic ions, metallic compounds, elemental carbon, organic compounds, and compounds from the Earth's crust. The size of the particles is directly linked to their potential for causing health problems.

Particles with a diameter of 10 micrometres or less (PM10) are inhalable into the lungs and can induce adverse health effects. Fine particulate matter, or PM2.5, is defined as particles that are 2.5 micrometres or less in diameter. PM2.5 comprises a portion of PM10 and is responsible for reduced visibility (haze). The largest sources of PM10 are coarse particles that consist of pollen, sea spray, and wind-blown dust from erosion, agricultural spaces, roadways, and mining operations. On the other hand, PM2.5 can be derived from primary sources, such as the combustion of fuels in power generation facilities, industries, or vehicles, and secondary sources, such as chemical reactions between gases.

Both short-term and long-term exposure to PM10 and PM2.5 are associated with adverse health effects. Short-term exposure to PM2.5 has been linked to premature mortality, increased hospital admissions for heart or lung causes, acute and chronic bronchitis, asthma attacks, emergency room visits, respiratory symptoms, and restricted activity days. These adverse effects have been reported primarily in infants, children, and older adults with pre-existing heart or lung diseases. Long-term exposure to PM10 and PM2.5 has been associated with respiratory mortality and lung cancer. Research has also shown that children living in communities with high levels of PM2.5 had slower lung growth and smaller lungs at age 18 compared to children who lived in communities with low PM2.5 levels.

Black carbon, also known as soot, is a major component of PM2.5 and is released through the incomplete combustion of fossil fuels, biofuels, and biomass. Short- and long-term exposure to black carbon have been associated with cardiovascular health effects and premature mortality. Overall, particulate matter pollution poses a serious risk to human health, with certain vulnerable populations, including children, older adults, and people with pre-existing health conditions, being at higher risk of adverse effects.

Sources of particulate matter

Particulate matter (PM) is a complex mixture of solid and/or liquid particles suspended in the air. These particles vary in size, shape, and composition. Some particles are large or dark enough to be seen with the naked eye, while others are so small they can only be detected using an electron microscope.

PM is found both outdoors and indoors. Outdoor sources of PM include car exhaust, smoke, road dust, pollen, some factory emissions, wildfires, burning buildings, and any other burning materials. PM levels are higher near busy roads and where people burn wood.

Indoor sources of PM include biological sources such as pollen, mold spores, dust mites, and cockroaches. Indoor activities such as smoking tobacco, cooking, burning wood, candles, or incense can also generate PM. In addition, particles can form indoors from complex reactions of gaseous pollutants emitted from household cleaning products, air fresheners, and chemicals released from activities like peeling an orange.

The largest particles, known as coarse particles, have a diameter between 2.5 and 10 micrometers. Sources of these particles include pollen, sea spray, wind-blown dust from erosion, agricultural spaces, roadways, and mining operations.

The finer particles, known as PM2.5, have a diameter of 2.5 micrometers or less. These particles are primarily derived from the combustion of fuels in power generation facilities, industries, or vehicles. They can also form from secondary sources such as chemical reactions between gases.

It is important to note that indoor PM can also be influenced by outdoor sources, as outdoor and indoor air mix. PM from outdoors can enter homes through open doors and windows, as well as small cracks and crevices.

Black carbon and its health effects

Particulate matter, or particle pollution, is a mix of solid and liquid particles in the air. These particles vary in size, shape, and chemical composition. Some particles are so small that they can only be seen with an electron microscope. When their levels are high, they cause a haze in the air.

Black carbon, or carbon black, is a major component of PM2.5, which are fine particles with a diameter of 2.5 microns or less. It is sometimes referred to as soot and is released through the incomplete combustion of fossil fuels, biofuels, and biomass. Black carbon is emitted from both anthropogenic and natural sources, with the largest sources being diesel-driven combustion engines, residential wood and coal burning, power stations using heavy oil or coal, field burning of agricultural wastes, and forest and vegetation fires.

Short-term exposure to PM2.5 has been linked to premature mortality, increased hospital admissions for heart or lung causes, acute and chronic bronchitis, asthma attacks, emergency room visits, respiratory symptoms, and restricted activity days. These adverse effects have been reported primarily in infants, children, and older adults with pre-existing heart or lung diseases. Long-term exposure to PM2.5 has been associated with an increased risk of strokes, coronary heart disease, and premature death.

Black carbon specifically has been associated with cardiovascular health effects and premature mortality. It is also a potent warming agent in the atmosphere, contributing to regional environmental disruption and accelerating glacier melting. Reducing people's exposure to PM2.5 containing black carbon is expected to lead to a reduction in the adverse health impacts associated with particulate matter.

Ultrafine particles and their impact

Particulate matter, also known as particle pollution or soot, is a mix of solid and liquid particles that vary in size, shape, and chemical composition. Ultrafine particles (UFP), a type of particulate matter with a diameter of 0.1 micrometres or less, pose significant health risks due to their small size and high toxicity.

These ultrafine particles, often found in large numbers in the air, typically enter the body through the lungs and can reach other organs, causing more inflammation and cellular toxicity than larger particles. Their increased toxicity is attributed to their smaller size, larger surface area, and the physical characteristics of the particles, including the adsorbed surface material. Ultrafine particles induce coughing, worsen asthma, and are linked to metal fume fever, a systemic disease characterised by lung inflammation. They also cause systemic inflammation, endothelial dysfunction, and coagulation changes, increasing the risk of ischemic cardiovascular disease and hypertension.

Dean Schraufnagel from the University of Illinois reviewed the health threats posed by nano-sized air pollutants, including ultrafine particles. Schraufnagel's research revealed that these particles elicit greater inflammatory responses and persist in the lungs longer than larger particles. Repeated exposure to ultrafine particles has been associated with triggering heart disease, diabetes, cancer, neurological disorders, and respiratory ailments, especially in children and individuals with long-term occupational exposure.

Short-term exposure to high levels of ultrafine particles can lead to acute health issues, including cardiovascular events, hospitalisations, and even mortality. Long-term exposure to low levels of these particles is equally harmful and can increase the risk of strokes, coronary heart disease, and premature death. A 2022 public health study in seven Western European countries found a strong association between long-term exposure to low levels of particulate matter and mortality from cardiovascular disease, respiratory issues, and lung cancer.

While everyone is at risk from the health impacts of particle pollution, those living near emission sources, such as power plants, industrial sites, and vehicles, are at higher risk. Other vulnerable subpopulations include people of colour, children, and older adults with pre-existing heart or lung diseases.

Vulnerable populations at higher risk

Particulate matter (PM) is a mixture of solids and aerosols composed of small droplets of liquid, dry solid fragments, and solid cores with liquid coatings. These particles vary widely in size, shape, and chemical composition and may contain inorganic ions, metallic compounds, elemental carbon, organic compounds, and compounds from the earth’s crust.

PM2.5, or fine particulate matter, is a significant health risk, especially for vulnerable populations. Short-term exposure to PM2.5 has been linked to a range of adverse health effects, including premature mortality, increased hospital admissions for heart or lung-related issues, acute and chronic bronchitis, asthma attacks, and respiratory symptoms. These impacts are most commonly seen in infants, children, and older adults with pre-existing heart or lung diseases.

Children are particularly vulnerable to the effects of air pollution, including particulate matter, as their bodies, organs, and immune systems are still developing. They inhale more air per pound of body weight than adults due to faster breathing rates, spend more time outdoors, and have smaller body sizes. Their immature immune systems also make them more susceptible to the harmful effects of pollutants.

In addition, certain population groups are more susceptible to the impacts of air pollution due to socioeconomic factors. Lower socioeconomic status is associated with increased exposure to air pollution, as people with limited financial resources often live closer to busy roads or industrial areas. This pattern is observed in Europe, where regions with lower GDP per capita tend to have higher levels of PM2.5 due to the combustion of low-quality solid fuels for domestic heating.

Furthermore, specific population groups may be more vulnerable to the health effects of particulate matter due to their physiological characteristics or pre-existing health conditions. For example, individuals with asthma, chronic heart or lung disease, and older adults with compromised health are at a higher risk of experiencing adverse health outcomes from exposure to particulate matter.

Overall, while particulate matter pollution affects everyone, vulnerable populations, including children, older adults, individuals with pre-existing health conditions, and those from lower socioeconomic backgrounds, are at a higher risk of experiencing the most harm from this type of air pollution.

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