Air Pollutants: Microscopic Killers In Our Air

Air pollution is a pressing issue that affects human health and the planet. According to the World Health Organization (WHO), nearly seven million deaths occur annually due to indoor and outdoor air pollution. Air pollutants come in various sizes, ranging from larger particles known as PM10, which irritate the eyes, nose, and throat, to smaller particles called PM2.5, which can penetrate deep into the lungs and even enter the bloodstream. These particles are produced by the combustion of fossil fuels, such as gasoline, oil, and diesel, as well as industrial emissions, vehicle exhaust, and natural sources like vegetation. While outdoor air pollution is a significant concern, indoor air pollution also plays a role, contributing to the overall impact on human health and the environment. The Clean Air Act in the United States aims to regulate and reduce these harmful emissions, but climate change poses challenges in meeting pollution standards.

Particle pollution: Particles vary in size, shape, and chemical composition

Particle pollution, or particulate matter (PM), refers to a mixture of solid particles and liquid droplets found in the air. These particles vary in size, shape, and chemical composition. They are defined by their diameter for air quality regulatory purposes.

PM10 particles are those with a diameter of 10 micrometres or less, which can be inhaled into the lungs and cause adverse health effects. These particles are often the result of human activities such as construction, waste burning, and industrial processes, as well as natural sources like dust from agricultural activities and pollen from vegetation.

PM2.5 particles, on the other hand, are fine inhalable particles with diameters of 2.5 micrometres or less. These particles are so small that they can only be detected using an electron microscope. They are primarily produced by the combustion of gasoline, oil, diesel fuel, or wood, as well as through chemical reactions of gases in the atmosphere. 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 premature mortality, increased hospital admissions for heart or lung issues, acute and chronic bronchitis, asthma attacks, and restricted activity days. Long-term exposure can lead to reduced lung function growth in children.

Both PM10 and PM2.5 particles can be directly emitted from sources (primary particles) or formed in the atmosphere through chemical reactions (secondary particles). These particles can remain in the atmosphere for days to weeks and can travel long distances, influencing the air quality of regions far from the original source. Particle pollution levels tend to be higher near busy roads, in urban areas, and in industrial zones.

The health effects of particle pollution are particularly harmful to certain vulnerable groups, including older adults with chronic heart or lung disease, children, and asthmatics. Regulatory bodies like the US Environmental Protection Agency (EPA) have implemented standards and alerts to help protect the public from harmful levels of particle pollution.

PM2.5: Smaller particles that can enter deep into the lungs and even the bloodstream

Particulate matter (PM) refers to a mixture of solid particles and liquid droplets found in the air. PM2.5 refers to fine inhalable particles with diameters of 2.5 micrometres or less. To put this in context, the average human hair is about 70 micrometres in diameter – making it 30 times larger than the largest fine particle.

PM2.5 particles are small enough to be inhaled and can enter the deeper parts of the lungs. They can also enter the bloodstream. These particles can be emitted directly from sources such as construction sites, unpaved roads, fields, smokestacks, or fires. They can also form in the atmosphere through complex chemical reactions involving pollutants such as sulfur dioxide and nitrogen oxides.

Emissions from the combustion of gasoline, oil, diesel fuel, or wood are a significant source of outdoor PM2.5 pollution. Indoor sources of PM2.5 include tobacco smoking, cooking, burning wood or incense, and household cleaning products.

PM2.5 is associated with a range of adverse health effects. Short-term exposure has been linked to premature mortality, increased hospital admissions for heart or lung issues, acute and chronic bronchitis, asthma attacks, and respiratory symptoms. Long-term exposure has been associated with premature death, particularly in those with chronic heart or lung diseases, and reduced lung function growth in children.

People with existing heart or lung conditions, children, older adults, and those from minority and low socioeconomic backgrounds are more vulnerable to the impacts of PM2.5 pollution.

PM10: Larger particles that irritate the eyes, nose, and throat

Air pollutants come in many forms, including smog, soot, greenhouse gases, and particulate matter. Particulate matter, or PM, is a mixture of chemical species, solids, and aerosols. It is composed of small droplets of liquid, dry solid fragments, and solid cores with liquid coatings. PM is categorised by particle size, with PM10 being one of the larger categories.

PM10 refers to particles with a diameter larger than PM2.5 and PM0.1. These particles are found in dust and smoke, and they can originate from combustion, construction, landfills, agriculture, wildfires, industry, and pollen. While PM2.5 particles can infiltrate the respiratory tract and reach the lungs, PM10 particles are larger and primarily affect the upper respiratory tract, including the eyes, nose, and throat.

Short-term exposure to PM10 has been linked to adverse health effects, particularly for those with pre-existing respiratory conditions. It can irritate the eyes, nose, and throat, causing symptoms such as coughing, sneezing, and a runny nose. Additionally, it can worsen respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD), leading to hospitalisations and emergency department visits.

Research has identified older adults with chronic heart or lung disease, children, and asthmatics as the groups most vulnerable to the adverse effects of PM10 exposure. Children are more susceptible due to their higher inhalation rate per pound of body weight, increased time spent outdoors, and immature immune systems.

While the long-term effects of PM10 exposure are less clear, several studies suggest a potential link to respiratory mortality. It is important to monitor air quality and take precautions to minimise exposure to harmful levels of PM10, especially for vulnerable individuals.

Sources of particle pollution: Fossil fuel combustion, industrial processes, and vehicle emissions

Air pollution refers to the release of pollutants into the air, which are detrimental to human health and the planet. According to the World Health Organization (WHO), around seven million deaths worldwide are caused by indoor and outdoor air pollution each year.

One of the major sources of particle pollution is the combustion of fossil fuels, such as gasoline, oil, diesel, and coal. When these fuels are burned, they release harmful chemicals and gases into the atmosphere, such as nitrogen oxides, sulfur dioxide, and carbon dioxide. These emissions contribute to the formation of smog and acid rain and climate change. Transportation is a significant contributor to air pollution from fossil fuel combustion, with cars, trucks, and buses powered by gasoline or diesel being major sources of nitrogen oxide and carbon dioxide emissions. In addition, the combustion of fossil fuels in power plants and industrial processes also releases pollutants into the air.

Vehicle emissions from cars, trucks, and buses are a significant source of particle pollution. In addition to nitrogen oxides and carbon dioxide, vehicles also emit pollutants such as sulfur dioxide and particulate matter. The pollution from vehicles is not limited to their operation but also includes the fuel production process. Electric vehicles, such as electric buses and trucks, emit no harmful tailpipe pollution and have significantly lower global warming emissions compared to vehicles powered by fossil fuels.

Industrial processes, such as mining, drilling, and fracking, also contribute to particle pollution. Mining operations, particularly strip mining, can release large amounts of carbon and other pollutants into the air. Fracking, which involves injecting water, chemicals, and sand into wells to extract oil and gas, has been linked to air and water pollution. Additionally, the processing and transportation of oil and gas can expose people to toxic air pollutants, including benzene and formaldehyde.

To reduce the impact of particle pollution from fossil fuel combustion, industrial processes, and vehicle emissions, several measures can be taken. These include improving energy efficiency, transitioning to renewable energy sources, and adopting cleaner transportation options, such as electric vehicles. Conserving energy, such as turning off electrical equipment when not in use, can also help reduce air pollution from energy production. Additionally, individuals can choose to walk, bike, or use public transportation instead of driving to reduce their contribution to vehicle emissions.

Health effects: Particle pollution is linked to respiratory and cardiovascular issues, and cancers

Particle pollution, also known as particulate matter, is a mix of tiny solid and liquid particles in the air. These particles can include acids, organic chemicals, metals, soil, and dust. The size of these particles varies, with smaller particles being more dangerous as they can get trapped deep in the lungs and even enter the bloodstream.

Respiratory Issues

Studies have linked particle pollution exposure to a variety of respiratory issues. These include respiratory symptoms such as coughing, phlegm, and wheezing, as well as inflammation of the airways and lungs, bronchial hyperreactivity, and acute phase reactions. Particle pollution can also lead to respiratory infections, decreased lung function growth in children, and chronic loss of pulmonary function in adults. It is also a risk factor for the development of asthma and can cause premature mortality in people with chronic lung disease.

Cardiovascular Issues

Particle pollution exposure is a known risk factor for cardiovascular disease. It can exacerbate existing cardiovascular conditions and contribute to the development of new ones. Acute and chronic exposure to particle pollution can increase the number of cardiovascular events, including hospitalizations for serious issues such as coronary syndrome, arrhythmia, heart failure, and stroke, especially in people with pre-existing heart disease.

Cancers

Particle pollution has been linked to lung cancer, with overwhelming evidence showing that outdoor air pollution, such as that from vehicle exhaust and industrial sources, is a contributing factor. In 2013, the World Health Organization (WHO) concluded that particulate matter causes lung cancer. Fine particles enter deep into the lungs and can initiate the cancerous process.

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