Air Pollutants: Their Harmful Impact On Our Health

Air pollution is a complex mix of solids and liquids in the air, including gases, dust, and smoke. It is a major threat to global health, causing more than 6.5 million deaths each year. While air pollution is a mix of hazardous substances, fine particulate matter (PM) is the air pollutant that contributes most significantly to adverse health effects. PM is composed of chemicals such as sulfates, nitrates, carbon, or mineral dust. These particles are so small that they can be inhaled deeply into lung tissue and contribute to serious health problems. Short-term exposure to PM has been associated with respiratory symptoms, asthma attacks, and restricted activity days, while long-term exposure increases the risk of lung cancer, heart disease, and stroke.

Particulate matter (PM)

PM is categorized into two types, based on the diameter of the particles:

• PM10: Particles with a diameter of 10 microns or less, which can be inhaled into the lungs and induce adverse health effects. Sources of PM10 include dust from construction sites, landfills, and agriculture, wildfires, industrial sources, wind-blown dust from open lands, pollen, and fragments of bacteria.
• PM2.5: Fine particulate matter, defined as particles that are 2.5 microns or less in diameter. These particles are so small that they can penetrate deep into the lungs and even enter the bloodstream, causing systemic damage to tissues and cells. Sources of PM2.5 include emissions from the combustion of gasoline, oil, diesel fuel, or wood, as well as certain organic compounds emitted by natural and anthropogenic sources.

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. Long-term exposure to PM2.5 has been associated with premature death, particularly in individuals with chronic heart or lung diseases, and reduced lung function growth in children.

Overall, particulate matter is a significant contributor to adverse health effects, with PM2.5 being associated with the greatest proportion of adverse health effects related to air pollution worldwide. It is important for individuals to stay informed about air quality and take appropriate measures to protect their health when PM levels are high.

Carbon monoxide (CO)

The most common symptoms of carbon monoxide exposure include fatigue, headaches, confusion, and dizziness, which are caused by inadequate oxygen delivery to the brain. In people with cardiovascular disease, short-term exposure to carbon monoxide can further compromise their body's ability to respond to increased oxygen demands during exercise or stress. This can lead to chest pain and decreased exercise tolerance. Prolonged exposure to high levels of carbon monoxide can have more severe consequences, including death.

Unborn babies are particularly vulnerable to the effects of carbon monoxide. High levels of CO exposure during pregnancy have been linked to adverse developmental effects in unborn babies, including an increased risk of preterm birth and low birth weight. Infants, young children, and the elderly are also more susceptible to the harmful effects of carbon monoxide due to their developing or weakened physiological systems. Additionally, individuals with anemia or a history of heart or respiratory disease are at a higher risk of experiencing health complications from elevated CO levels.

Carbon monoxide poisoning cases tend to increase during the cold season due to the increased use of improperly vented space heaters and gas ranges for heating. Over 400 people in the United States die each year from CO poisoning, with a significant number of cases occurring in California. To mitigate this risk, California has mandated the installation of carbon monoxide detectors in all housing units in the state.

In addition to its direct health impacts, carbon monoxide also contributes to atmospheric chemical reactions that result in the formation of ozone air pollution and influence climate change. Overall, carbon monoxide is a significant air pollutant that poses a serious threat to public health and welfare.

Ozone (O3)

Ozone is a highly reactive gas that can be found at ground level, especially in areas with high industrial activity and vehicle emissions. It is formed through chemical reactions between nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the presence of sunlight. While ozone in the upper atmosphere protects life on Earth by absorbing ultraviolet radiation, ground-level ozone is a harmful pollutant.

The health effects of ozone pollution are primarily related to the respiratory system. When inhaled, ozone irritates and inflames the lining of the airways, leading to symptoms such as coughing and chest tightness. It can also worsen asthma symptoms, trigger asthma attacks, and lead to increased school absences, medication use, and hospital admissions. People with asthma are particularly susceptible to the harmful effects of ozone, as it can cause the muscles in the airways to constrict, trapping air in the alveoli and further damaging the airway lining.

Children are considered to be at the greatest risk from ozone exposure. This is because their lungs are still developing, and they tend to spend more time outdoors engaging in physical activities when ozone levels are typically at their highest. Additionally, children are more likely to have asthma, further increasing their vulnerability to ozone pollution.

Long-term exposure to ozone pollution can have even more severe health consequences. It is likely to be one of the many causes of asthma development and may contribute to respiratory-related deaths. The effects of ozone exposure can vary widely among individuals, even with similar doses and exposure durations. However, research has shown that outdoor workers and individuals with certain genetic characteristics or nutrient deficiencies are also at higher risk of adverse health effects from ozone pollution.

Nitrogen dioxide (NO2)

One of the most concerning health impacts of NO2 is its effect on respiratory health. Short-term exposure to high concentrations of NO2 can irritate the airways and aggravate respiratory conditions, especially asthma. This can lead to coughing, wheezing, and difficulty breathing, often resulting in hospital admissions and visits to emergency rooms. Prolonged exposure to elevated levels of NO2 may also contribute to the development of asthma and increase the risk of respiratory infections. People with pre-existing respiratory conditions, such as asthma, children, and the elderly, are generally more susceptible to the harmful effects of NO2 on respiratory health.

Nitrogen dioxide also has adverse effects on cardiovascular health. Scientific studies have found associations between elevated levels of NO2 and an increased risk of heart-related issues. This includes links to premature mortality, increased hospital admissions for heart-related causes, and the worsening of existing cardiovascular diseases. The harmful impact of NO2 on cardiovascular health is a significant concern, particularly for vulnerable populations.

In addition to respiratory and cardiovascular effects, NO2 exposure has been linked to adverse pregnancy and birth outcomes. Research suggests that exposure to NO2 may increase the risk of preterm birth, low birth weight, and developmental issues in children. There is also growing evidence of a potential link between NO2 exposure and an increased risk of neurological harm, autoimmune disorders, and cancer. These adverse health effects of NO2 pollution highlight the importance of implementing measures to reduce NO2 emissions and improve air quality.

While steps have been taken to reduce NO2 emissions, such as the federal Clean Air Act, which has driven down nitrogen dioxide emissions from power plants and industrial sites, it is clear that more needs to be done. Individuals living near emission sources, such as industrial facilities or major roads, are at a higher risk of experiencing the harmful health impacts of NO2. To protect public health, it is crucial to continue advocating for the reduction of air pollution, especially in vulnerable communities that are often disproportionately affected by air pollutants.

Sulphur dioxide (SO2)

SO2 can have harmful effects on the respiratory system, especially for individuals with asthma. Short-term exposure to high concentrations of SO2 can lead to wheezing, shortness of breath, and chest tightness, especially during physical activity. This is because rapid breathing during exercise helps SO2 reach the lower respiratory tract, as does breathing through the mouth. For people with asthma, short-term exposure to peak levels of SO2 can make it difficult to breathe when they are active outdoors. It is also important to note that children and older adults are particularly vulnerable to the respiratory effects of SO2.

Long-term exposure to high levels of SO2 can have more severe consequences. It increases respiratory symptoms and reduces lung function, making it harder for individuals to breathe and increasing their risk of hospitalisation or emergency room visits. Additionally, long-term exposure to SO2 and other air pollutants has been linked to an increased risk of lung cancer.

The impact of SO2 exposure is not limited to respiratory issues. Research has indicated links between air pollution, including SO2, and adverse pregnancy outcomes such as low birth weight and preterm birth. Long-term exposure to particle pollution, which includes SO2, has also been associated with an increased risk of developing diabetes and subsequent complications. Furthermore, air pollution has been suggested to impact neurological development in children and increase the risk of cognitive impairment in adults.

While SO2 emissions have decreased over time due to policies promoting cleaner fuels and pollution controls, it remains a significant health concern. Individuals living or working near major sources of SO2 emissions, such as power plants, ports, and smelters, are at the highest risk of exposure. These vulnerable communities are often economically disadvantaged and suffer from systemic racism, which has contributed to the disproportionate impact of air pollution on their health.

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