Air Pollution: What's The Deadliest For Human Health?

Air pollution is a mix of hazardous substances from both human-made and natural sources, and it is a major threat to global health. It is the presence of one or more contaminants in the atmosphere, such as dust, fumes, gas, mist, odour, smoke or vapour, in quantities and durations that can be harmful to human health. While air pollution affects people differently, it is a risk for all-cause mortality and specific diseases. Fine particulate matter (PM2.5) is the air pollutant driving the most significant health problems and premature mortality. In this context, it is important to understand which type of air pollution is causing more human health problems.

Fine particulate matter (PM2.5)

Fine particulate matter, also known as PM2.5, is a type of air pollution composed of tiny particles or droplets in the air that are 2.5 micrometres or less in diameter. To put this into perspective, a human hair is typically around 70 micrometres in diameter, making the largest PM2.5 particles approximately 30 times smaller. These particles can be made up of a variety of substances, including solids, liquids, inorganic ions, metallic compounds, elemental carbon, and organic compounds. They are often emitted from sources such as construction sites, unpaved roads, fields, smokestacks, and fires.

Due to their extremely small size, PM2.5 particles can pose significant health risks when inhaled. They are able to travel deeply into the respiratory tract and reach the lungs, where they can cause a range of short-term health effects, including eye, nose, throat, and lung irritation, coughing, sneezing, a runny nose, and shortness of breath. Additionally, exposure to PM2.5 can worsen existing medical conditions, such as heart disease and asthma, and increase the risk of heart attacks.

The health impacts of PM2.5 exposure can vary depending on the levels and duration of exposure. Short-term exposure to high levels of PM2.5 can lead to respiratory infections and aggravated asthma. On the other hand, long-term or chronic exposure to fine particulate matter has been linked to more serious health issues, including an increased risk of stroke, heart disease, chronic obstructive pulmonary disease, and cancer. Children are particularly vulnerable to the effects of PM2.5, with research showing that those living in areas with high levels of PM2.5 experience slower lung growth and have smaller lungs at age 18 compared to those in low PM2.5 areas.

PM2.5 air pollution is a global issue, with 97% of the urban population exposed to concentrations above the health-based guidelines set by the World Health Organization in 2021. This has resulted in a significant number of premature deaths, with approximately 238,000 attributed to PM2.5 in the 27 EU Member States in 2020. The sources of particulate matter vary, but residential, commercial, and institutional energy consumption, as well as the manufacturing and extractive industries, are significant contributors.

Short-term exposure

Another critical pollutant is ground-level ozone (O3), which is a powerful lung irritant. Short-term exposure to ozone can cause respiratory problems such as chest tightness, coughing, and shortness of breath. It can also worsen existing respiratory conditions, leading to increased medication use and emergency department visits. Children who play outdoor sports and live in high-ozone communities are more likely to develop asthma due to ozone exposure.

Furthermore, short-term exposure to nitrogen oxides has been linked to an increased risk of hemorrhagic stroke in post-menopausal women. Exposure to carbon monoxide (CO), a toxic gas produced by the incomplete combustion of fuels, can also have detrimental health effects. While the levels and duration of exposure that are considered safe vary by pollutant, short-term exposure to air pollution can lead to a range of health problems, including cardiac issues, hospital admissions, and emergency room visits.

Long-term exposure

One of the most significant health problems associated with long-term exposure to air pollution is the increased risk of developing non-communicable diseases, including stroke, heart disease, chronic obstructive pulmonary disease (COPD), and cancer. Fine particulate matter (PM2.5) is a critical pollutant in this regard, as it can penetrate deep into the lungs, enter the bloodstream, and travel to other organs, causing systemic inflammation and increasing the risk of these diseases. The World Health Organization (WHO) has set health-based guideline levels for PM2.5, but in 2021, 97% of the urban population in the EU was exposed to concentrations above this level.

Another important health concern is the impact of air pollution on respiratory health. Long-term exposure to pollutants such as ozone (O3) can cause lasting damage to the respiratory system, including inflammation and systemic stress, which can worsen other disease conditions over time. High levels of ozone in the atmosphere can lead to breathing problems such as chest tightness, coughing, and shortness of breath, even in healthy young adults.

Additionally, long-term exposure to air pollution has been linked to adverse pregnancy outcomes, including low birth weight, pre-term birth, and small gestational age births. There is also growing evidence suggesting a link between air pollution and an increased risk of diabetes, cognitive impairment, and neurological diseases.

Socioeconomic status plays a significant role in the health impacts of long-term air pollution exposure. People living in low-income areas or with lower socioeconomic status often face higher levels of exposure to air pollution due to their proximity to sources of pollution and limited resources to relocate. They may also have poorer health, limited access to quality healthcare, and experience psychosocial distress, which can make them more vulnerable to pollution-related health effects.

Ozone

Long-term exposure to ozone is associated with increased respiratory illnesses, metabolic disorders, nervous system issues, and reproductive problems. It can also lead to reduced fertility and poor birth outcomes. Furthermore, ozone exposure can increase the risk of respiratory and cardiovascular-related mortality, contributing to premature death. Research has shown that the risk of premature death increases with higher levels of ozone exposure.

Carbon monoxide

Air pollution is the presence of contaminants in the atmosphere, such as dust, fumes, gases, and smoke, which can be harmful to human health. One of the most common and critical air pollutants is fine particulate matter, which can cause significant health issues and even premature mortality. Carbon monoxide (CO) is one such pollutant, and it is produced by the incomplete combustion of carbon-containing fuels like natural gas, gasoline, or wood. Motor vehicles, power plants, wildfires, and incinerators are all common sources of CO emissions.

The health effects of carbon monoxide exposure are not limited to the cardiovascular system. Respiratory problems have also been associated with carbon monoxide, particularly in individuals with asthma. Studies have found links between increasing carbon monoxide concentrations and exacerbations of asthma symptoms, resulting in hospitalizations and emergency room visits. Additionally, carbon monoxide exposure can cause immediate symptoms such as fatigue, headaches, confusion, and dizziness due to inadequate oxygen delivery to the brain.

Certain populations are more vulnerable to the health impacts of carbon monoxide. Unborn babies, infants, elderly people, and individuals with anemia or a history of heart or respiratory disease are at a higher risk of experiencing adverse health effects from elevated levels of carbon monoxide exposure. During the cold season, cases of carbon monoxide poisoning tend to increase due to the increased use of indoor heating sources, such as improperly vented space heaters or gas ranges. California has recognized the seriousness of this issue by mandating the installation of CO detectors in all housing units in the state.

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