Air Pollutants: Harmful Toxins In The Air We Breathe

Air pollution is a major threat to human health and the planet, causing around 7 million premature deaths annually. According to the World Health Organization (WHO), 99% of people worldwide breathe air that exceeds the recommended guideline limits for pollutants. Air pollution is caused by the release of pollutants such as smog, soot, greenhouse gases, and fine particulate matter, which can lead to serious health issues, including respiratory and cardiovascular problems, strokes, lung cancer, and other diseases. These pollutants come from various sources, including household combustion devices, motor vehicles, industrial facilities, and forest fires, and can have both short-term and long-term impacts on human health.

Particulate matter, carbon monoxide, ozone, nitrogen dioxide, and sulfur dioxide

Air pollution is detrimental to human health and the planet as a whole. According to the World Health Organization (WHO), nearly seven million deaths occur annually due to indoor and outdoor air pollution.

Particulate Matter

Particulate matter (PM) is a complex mixture of extremely small particles and liquid droplets made up of acids, organic chemicals, metals, and soil or dust particles. PM is categorised by size and is the fraction of air pollution most reliably associated with human disease. It contributes to cardiovascular and cerebrovascular disease through mechanisms such as systemic inflammation, direct and indirect coagulation activation, and direct translocation into systemic circulation.

Carbon Monoxide

Carbon monoxide (CO) is a colourless, odourless gas released when something is burned. It can be harmful when inhaled in large amounts, reducing the amount of oxygen transported via the bloodstream to critical organs. At very high levels, CO can cause dizziness, confusion, unconsciousness, and even death. The greatest sources of outdoor CO are vehicles and machinery that burn fossil fuels, while indoor sources include unvented kerosene heaters, leaking chimneys, and gas stoves.

Ozone

Ground-level ozone (O3) is a harmful air pollutant formed in the troposphere by the interaction between sunlight and precursor gases, particularly nitrogen oxides and volatile organic compounds. High ambient ozone levels are often observed during warm seasons and are associated with adverse respiratory health outcomes, including asthma aggravation, chronic obstructive pulmonary disease, lower lung function, and infections.

Nitrogen Dioxide

Nitrogen dioxide (NO2) is a toxic gas found in polluted regions, especially near the ground. It is primarily produced by burning fossil fuels for transportation, power generation, and industrial activity, as well as wildfires. Nitrogen dioxide plays a crucial role in the formation of ground-level ozone and particulate matter pollution, contributing to poor air quality and health issues for humans and ecosystems.

Sulfur Dioxide

Sulfur dioxide (SO2) is a highly reactive gas emitted into the air as a result of fossil fuel combustion and industrial processes. High concentrations of SO2 in the air contribute to the formation of other sulfur oxides (SOx), which can lead to particulate matter pollution and health issues. SO2 and SOx can also contribute to acid rain, damaging foliage and ecosystems, and causing haze that reduces visibility.

Wildfires and wood smoke

The complex mixture of pollutants in wildfire smoke also includes hazardous air pollutants (HAPs), such as polycyclic aromatic hydrocarbons (PAHs), and gaseous pollutants like carbon monoxide. These pollutants can have serious health implications, with studies indicating a potential link between wildfire smoke exposure and adverse cardiovascular and respiratory outcomes. The intensity of wildfire smoke seems to play a role in the severity of these health effects.

Wood smoke, particularly during residential burning in the winter, significantly contributes to fine particle pollution. Efficient burning practices, such as using dry, seasoned wood and EPA-certified stoves, can help reduce smoke emissions. However, even with improved burning methods, wood smoke remains a health hazard, especially for vulnerable populations. These at-risk groups include children, teenagers, older adults, individuals with pre-existing heart or lung diseases, outdoor workers, and people of low socioeconomic status.

The health effects of wood smoke exposure can vary, with some experiencing eye and respiratory tract irritation, while others may suffer more severe consequences, such as exacerbating asthma and heart failure, and even leading to premature death. Additionally, wood smoke can affect the body's ability to clear foreign materials, like viruses and bacteria, from the lungs, potentially increasing the risk of lung infections, including COVID-19.

To minimize the health risks associated with wildfires and wood smoke, it is essential to stay informed about air quality conditions, especially in areas prone to wildfires. Taking precautions, such as staying indoors with closed windows, using air conditioning with recirculating settings, and wearing NIOSH-approved masks, can help reduce exposure to harmful smoke particles.

Vehicle exhaust

One of the major components of diesel exhaust is soot, which accounts for 60%-80% of what is emitted. These fine particles are easily inhaled and can be deposited deep into the lung tissue, causing various health issues. Pre-existing diseases, such as emphysema, asthma, or heart disease, can be aggravated by diesel exhaust. The National Institute for Occupational Safety and Health (NIOSH) considers diesel exhaust a potential human carcinogen (cancer-causing substance). Additionally, the World Health Organization has stated that long-term repeated exposure to diesel exhaust fumes may increase the risk of lung cancer.

Another harmful substance emitted by vehicles is carbon monoxide (CO), an invisible, toxic gas produced by the incomplete combustion of fuel. While newer engines produce less carbon monoxide, older engines can emit high levels. Other pollutants include nitrogen oxide (NOx), a highly reactive product of any combustion process, and ultrafine particulates (UFP), which are found in elevated levels near highways, motorways, and freeways. People living or spending substantial time within 200 meters of these major roads are exposed to higher levels of pollutants, increasing the risk of developing asthma and experiencing reduced lung function.

To mitigate the impact of vehicle exhaust on air quality and public health, several measures have been implemented. Car manufacturers are reducing exhaust emissions through improved engine and exhaust system designs, and catalytic converters and particulate filters are now standard on all new petrol and diesel cars. Many cities have also introduced clean air zones, such as London's Ultra Low Emission Zone, to discourage the most polluting vehicles from entering.

Short-term exposure to fine particles can trigger asthma attacks

Air pollution is a pressing issue that affects human health and the planet. According to the World Health Organization (WHO), indoor and outdoor air pollution is responsible for approximately seven million deaths worldwide each year. Air pollution is closely linked to the burning of fossil fuels and the subsequent release of greenhouse gases, which contribute to global warming and worsen the health impacts of air pollution.

One of the most vulnerable groups affected by air pollution is children with asthma. Studies have shown that poor air quality can trigger asthma attacks and worsen symptoms in children, with six million children in the United States alone being particularly vulnerable. Outdoor pollutants can migrate indoors, and both indoor and outdoor asthma triggers can exacerbate the condition.

Particulate matter (PM) is a significant contributor to air pollution and has detrimental effects on respiratory health. PM is a complex mixture of dirt, soot, smoke, and liquid droplets from natural and anthropogenic sources. It penetrates deep into the lungs, causing inflammation and increasing the frequency and severity of asthma attacks. Exposure to PM has been linked to an estimated 16 million incident cases of childhood asthma annually.

To protect against the harmful effects of air pollution, individuals can take precautions such as staying away from heavily trafficked roads, showering and changing clothes after outdoor exercise, and utilizing tools like the EPA's AirNow to monitor air quality. During periods of poor air quality, limiting outdoor activities, using air conditioning with the recirculating setting, and wearing masks can help reduce exposure to pollutants.

Additionally, dietary supplements such as carotenoids, vitamin D, and vitamin E may offer some protection against airway inflammation caused by pollutants. Inhaled corticosteroids (ICSs) have also been found to be beneficial in reducing adverse responses to pollutant exposures in asthmatic patients. By understanding the impact of air pollution on asthma, healthcare providers can educate patients on minimizing exposure and managing their condition effectively.

Long-term exposure to air pollutants can cause lung cancer

Air pollution is a major public health concern, causing nearly seven million premature deaths worldwide each year. It refers to the release of pollutants into the atmosphere that are detrimental to human health and the planet. Long-term exposure to air pollutants can cause serious health issues, including lung cancer.

Particle pollution, a mix of tiny solid and liquid particles in the air, is a significant contributor to lung cancer risk. These particles, known as PM2.5, are 2.5 micrometres or smaller in diameter and can penetrate deep into the lungs, even entering the bloodstream. Sources of particle pollution include vehicle exhaust, coal-fired power plants, industrial sources, and household combustion devices.

Research has shown that exposure to these fine particles can cause changes in airway cells, triggering lung cancer even in those who have never smoked. Studies have found higher rates of lung cancer, specifically EGFR mutant lung cancer, in areas with elevated levels of PM2.5 pollution. Additionally, air pollution can wake up dormant cancer-causing cells in the lungs, encouraging their growth and the potential formation of tumours.

The health impacts of air pollution are far-reaching and not limited to lung cancer. It can also worsen respiratory symptoms, increase fatigue, reduce physical activity, and negatively affect the quality of life for people with cancer. Furthermore, it can interfere with cancer treatments, reducing the effectiveness of chemotherapy and increasing surgical complications.

To mitigate the harmful effects of air pollution, it is essential to transition to renewable energy sources, improve fuel efficiency, and adopt electric vehicles. These measures not only reduce air pollution but also help curb global warming and provide numerous health and economic benefits.

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