Air Pollution: What's Not Caused By It?

Air pollution is a pressing issue that poses serious health risks to populations worldwide. It is caused by various human activities, such as driving vehicles, burning fossil fuels, and industrial emissions. The presence of contaminants in the atmosphere, including gases, particles, and biological molecules, can have detrimental effects on both human health and the environment. While the specific health impacts vary based on individual factors, air pollution has been linked to respiratory issues, cardiovascular diseases, lung cancer, and even premature death. As a result, it is crucial to address air pollution through interventions, policies, and sustainable practices to mitigate its adverse effects on public health and the planet.

Particulate matter

PM10 particles are inhaled into the lungs and can induce adverse health effects, primarily the worsening of respiratory diseases, including asthma and chronic obstructive pulmonary disease (COPD). The effects of long-term exposure to PM10 are less clear, but several studies suggest a link to respiratory mortality.

PM2.5 particles pose a greater risk to health and are the main cause of reduced visibility (haze) in some regions. These fine particles can penetrate deep into the lungs and even enter the bloodstream. Long-term exposure to PM2.5 has been linked to premature death, particularly in individuals with pre-existing heart or lung conditions, and impaired lung development in children. According to the World Health Organization's Global Burden of Disease Project, PM2.5 is associated with the highest proportion of adverse health effects related to air pollution globally.

The sources of particulate matter vary. Larger particles, or coarse particles, often originate from pollen, sea spray, and wind-blown dust from erosion, agricultural spaces, roadways, and mining operations. In contrast, the finer PM2.5 particles can be derived from primary sources, such as the combustion of fuels in power generation facilities, industries, or vehicles, and secondary sources like chemical reactions between gases.

Household combustion devices, motor vehicles, industrial facilities, and forest fires are significant contributors to particulate matter air pollution. Indoor sources, such as smoking tobacco, cooking, burning wood, candles, or incense, also play a role in indoor PM levels. Additionally, particles can form indoors from complex reactions involving gaseous pollutants emitted from household cleaning products and air fresheners.

Carbon monoxide

Due to its invisible, odourless, and tasteless nature, carbon monoxide can be extremely dangerous, as people may not be aware of its presence until it is too late. At very high levels, carbon monoxide can cause dizziness, confusion, unconsciousness, and even death. It is particularly harmful to individuals with heart disease, as it can reduce the oxygen supply to the heart, leading to chest pain or angina. The acute effects of carbon monoxide exposure are due to the formation of carboxyhemoglobin in the blood, which inhibits oxygen intake.

To mitigate the risks associated with carbon monoxide exposure, it is recommended to have carbon monoxide detectors installed in homes, particularly near sleeping areas. Regular inspections and proper ventilation of fuel-burning appliances are also crucial to ensure safe indoor air quality. Additionally, reducing the use of private vehicles and transitioning to cleaner energy sources, such as CNG or Compressed Natural Gas, can help decrease carbon monoxide emissions and improve air quality.

While carbon monoxide is primarily a concern for human health, it also contributes to climate change. It participates in chemical reactions in the atmosphere, leading to the production of ozone, a potent climate change gas. Therefore, reducing carbon monoxide emissions is not only essential for protecting human health but also for mitigating the impacts of global warming.

Ozone

Long-term exposure to ozone is linked to the aggravation of asthma and is likely one of the causes of asthma development. It has been compared to skin inflammation caused by sunburn. People most at risk from breathing air containing ozone include those with asthma, children, older adults, and people who are active outdoors, especially outdoor workers. Some evidence also suggests that women may face a higher respiratory health risk from ozone.

Nitrogen dioxide

The presence of nitrogen dioxide in the atmosphere can have detrimental effects on both human health and ecosystems. It is a toxic gas that can cause respiratory and other diseases. According to the World Health Organization (WHO), almost the entire global population (99%) breathes air that exceeds the recommended limits and contains high levels of pollutants, including nitrogen dioxide. This exposure contributes to morbidity and mortality, with air pollution being associated with approximately 6.7 million premature deaths annually.

To address the issue of nitrogen dioxide pollution, interventions and initiatives are being promoted by organizations like WHO. These include policies and investments that support sustainable land use, cleaner household energy, improved municipal waste management, and the electrification of healthcare facilities. Additionally, technological advancements such as the Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument provide valuable data on nitrogen dioxide levels, allowing for better knowledge of pollution sources and population exposure.

It is important to note that while nitrogen dioxide is a significant contributor to air pollution, it is not the only pollutant. Other harmful substances include particulate matter, carbon monoxide, ozone, sulfur dioxide, and volatile organic compounds. By addressing these various pollutants and implementing measures to reduce their presence in the atmosphere, we can work towards improving air quality and mitigating the adverse health and environmental impacts associated with air pollution.

Lung cancer

Air pollution is a significant contributor to lung cancer, and the second leading cause. Outdoor air pollution, particularly particulate matter (PM) with an aerodynamic diameter of less than 2.5 microns (PM2.5), has been classified as carcinogenic to humans and a cause of lung cancer. PM2.5 is composed of inhalable particles such as sulphate, nitrates, ammonia, sodium chloride, black carbon, mineral dust, or water. These fine particles 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.

The Global Burden of Disease 2019 study estimated that 15% of global lung cancer deaths were attributable to PM2.5 in outdoor air. Additionally, household air pollution from the use of solid fuels for cooking and radon exposure contribute to 4% each of global lung cancer deaths. In China, approximately 180,000 deaths annually and 25.8% of disability-adjusted life years due to lung cancer are linked to air pollution.

The link between air pollution and lung cancer is well-established. Particles linked to climate change promote cancerous changes in airway cells, particularly those with EGFR and KRAS gene mutations. Long-term exposure to air pollution has been associated with increased mortality risk for lung cancer, with a 36% higher risk for every 10 microgram per cubic meter (µg/m3) increase in PM2.5 exposure.

Reducing air pollution is crucial to lowering the risk of lung cancer and other lung diseases. Advocating for sustainable land use, cleaner household energy, efficient transportation, energy-efficient housing, and better waste management can effectively reduce air pollution and its associated health risks.

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