Air Pollution: When Does It Start?

Air pollution is a serious issue that has been affecting human health and the planet as a whole. It refers to the release of pollutants into the air, which can be detrimental to human health and the environment. While the definition of polluted air may vary, air pollution is generally considered to occur when the air quality is unhealthy, posing risks to human health and the environment. According to the World Health Organization (WHO), air pollution is responsible for millions of deaths worldwide each year, with 99% of humans currently breathing air that exceeds the recommended limits for pollutants. Air pollution can come from various sources, including energy use, transportation, power plants, manufacturing, and the burning of materials such as wood, biomass, and fossil fuels. It is important to address and reduce air pollution to protect public health and the planet.

The Air Quality Index (AQI)

The AQI tracks six common air pollutants, including ozone (smog) and particle pollution (from sources like smoke, power plants, factories, and vehicle exhaust). The AQI for a location is the highest of the AQI values for each pollutant being monitored at that location. AQI values reflect air quality management objectives, which are based on the lowest achievable emissions rate. The AQI can increase due to an increase in air emissions, such as during rush-hour traffic or an upwind forest fire.

The AQI is calculated using an air pollutant concentration over a specified averaging period, obtained from an air monitor or model. The concentration and time together represent the dose of the air pollutant. The AQI values are typically grouped into ranges, with each range assigned a descriptor, a color code, and a standardized public health advisory. For instance, a "code orange" day indicates elevated air pollution levels, and a purple or maroon day indicates that everyone should try to stay indoors.

The AQI also considers the health risks associated with air pollution. It provides advice on how to protect one's health during periods of low, moderate, high, and very high health risks. For example, during periods of high air pollution, individuals are advised to avoid prolonged outdoor activity and to stay away from high-traffic areas. Certain individuals, such as children, the elderly, pregnant women, and those with asthma or other lung diseases, are especially vulnerable to the harmful effects of air pollution.

Overall, the AQI is a valuable tool for monitoring air quality and protecting public health. It helps individuals make informed decisions about their activities and provides guidance on reducing exposure to air pollution. By keeping track of the AQI, individuals can take proactive steps to safeguard their health and well-being.

Greenhouse gases

The primary greenhouse gases are water vapour, carbon dioxide, methane, nitrous oxide, and ozone. Water vapour is the most abundant greenhouse gas, accounting for about half of the greenhouse effect. Carbon dioxide (CO2) is released into the atmosphere through the burning of fossil fuels, solid waste, trees, and other biological materials, as well as certain industrial processes like cement production. Human activities since the Industrial Revolution have increased carbon dioxide levels in the atmosphere by over 50%. Methane and nitrous oxide are also significant contributors to the greenhouse effect, with methane levels increasing by 150% due to human activities.

In addition to these naturally occurring greenhouse gases, human activities have introduced synthetic greenhouse gases, such as hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). These gases are emitted from a range of household, commercial, and industrial applications. While they are present in smaller concentrations compared to natural greenhouse gases, they are much more potent in their ability to trap heat. For example, SF6 has a Global Warming Potential (GWP) 23,000 times greater than CO2.

The increase in the concentration of greenhouse gases in the atmosphere has led to global warming and climate change. The higher the concentration of these gases, the more energy is absorbed, resulting in a positive radiative forcing. This positive forcing means more energy is retained in the atmosphere, causing the planet to warm. The consequences of this warming include rising global temperatures, melting ice caps, rising sea levels, and altered weather patterns.

To address the issue of greenhouse gas emissions and mitigate their impact on the planet, efforts are being made to reduce the use of these gases and transition to renewable energy sources. For instance, in 2016, over 140 countries signed the Kigali Agreement, committing to reducing the use of hydrofluorocarbons and developing greener alternatives.

Health impacts

Air pollution has detrimental health effects on humans, causing millions of premature deaths annually. According to the World Health Organization (WHO), approximately seven million deaths worldwide are attributed to indoor and outdoor air pollution each year. Moreover, 99% of people currently breathe air that surpasses the WHO's guideline limits for pollutants, disproportionately impacting those residing in low- and middle-income countries.

The health impacts of air pollution are far-reaching and varied, affecting individuals from all demographics. However, certain groups are more vulnerable to the adverse effects of air pollution, including children, teenagers, pregnant women, and individuals with pre-existing respiratory conditions or chronic illnesses. For instance, air pollutants can aggravate asthma symptoms, trigger asthma attacks, and increase the risk of respiratory illnesses, leading to higher emergency department visits and hospital admissions.

One of the critical pathways by which air pollutants harm human health is through direct exposure to toxic gases. These gases can have acute effects, particularly on individuals with respiratory conditions such as asthma or chronic obstructive pulmonary disease (COPD). Additionally, pollutants contribute to the formation of particulate matter, which consists of tiny particles that can infiltrate the lungs, airways, and, in some instances, even the bloodstream. The smaller the particulate matter, the more detrimental it tends to be to human health.

Climate change further exacerbates the health impacts of air pollution. For example, pollen allergies are worsening due to increased carbon dioxide levels, leading to more prominent symptoms such as runny noses, fevers, and itchy eyes. Climate change also prolongs the pollen production season, and there is emerging evidence that ragweed pollen may be becoming a more potent allergen. Consequently, more individuals are at risk of experiencing asthma attacks, which can be life-threatening.

Air pollution also has indirect health impacts. For instance, it contributes to ground-level ozone pollution, which is harmful to human health and welfare, even at very low levels. Additionally, air pollution affects communities of color disproportionately. They are more likely to reside in areas with failing grades for air quality and have higher rates of chronic conditions, such as asthma, diabetes, and heart disease, that increase their vulnerability to air pollution.

Sources of pollution

Air pollution refers to the release of pollutants into the air that are detrimental to human health and the planet. According to the World Health Organization (WHO), indoor and outdoor air pollution is responsible for nearly seven million deaths worldwide each year. Ninety-nine per cent of human beings currently breathe air that exceeds the WHO's guideline limits for pollutants, with those living in low- and middle-income countries suffering the most.

There are four main types of air pollution sources: mobile, stationary, area, and natural. Mobile sources include cars, buses, planes, trucks, and trains. These account for more than half of all air pollution in the United States, with automobiles being the primary source. Stationary sources, such as power plants, oil refineries, industrial facilities, and factories, emit large amounts of pollution from a single location. Area sources are made up of smaller pollution sources that can have a significant collective impact, including agricultural areas, cities, and wood-burning fireplaces. Natural sources include wind-blown dust, wildfires, and volcanoes.

Pollutants from these sources can create haze and have biological effects. For example, elevated ozone concentrations can form from tailpipe emissions and industrial processes. Summertime wildfires can reduce visibility and contribute to particle pollution. Power plants that lack modern pollution controls can increase smog levels in nearby areas.

In addition to these broad categories, specific sources of air pollution include residential wood burning, vehicles, local businesses, heating and cooling equipment, gas-powered yard tools, agricultural equipment, boats, snowmobiles, and more. Older diesel engines, in particular, produce significantly more fine particulate pollution than newer models.

To address air pollution, various efforts have been made, such as the federal regulation of car manufacturing and fuel production, the removal of lead from gasoline, and the reduction of sulfur in diesel fuel. The 2006 Mercury Emissions Reduction Act in Minnesota required coal-fired power plants to significantly reduce mercury and haze-forming pollutant emissions. The Kigali Agreement, signed by over 140 countries, aims to reduce hydrofluorocarbons (HFCs) in air conditioners and refrigerators.

Interventions to reduce pollution

Air pollution is a serious issue that affects the health of humans and the planet. According to the World Health Organization (WHO), around seven million deaths occur annually due to indoor and outdoor air pollution, with 99% of people currently breathing air that exceeds the recommended guideline limits for pollutants. While individual actions can help reduce exposure, systemic interventions are necessary for broader impact. Here are some key interventions to reduce pollution:

• Transition to Renewable Energy Sources: Phasing out the use of coal and other fossil fuels, such as lignite and tar products, for power production is crucial. This transition to renewable sources like wind and solar energy can significantly improve health and combat climate change. The Kigali Agreement, signed by over 140 countries, aims to reduce the use of hydrofluorocarbons (HFCs) and develop greener alternatives, which is a step in the right direction.
• Improve Air Quality in Low- and Middle-Income Countries: According to WHO, 91% of premature deaths due to air pollution occur in low- and middle-income countries. Interventions should focus on providing access to clean household energy, improving waste management practices, and implementing cleaner transport solutions in these regions.
• Implement Clean Technologies in Industries: Industries can adopt clean technologies to reduce emissions from industrial smokestacks. Capturing methane gas emitted from waste sites and utilising it as biogas instead of incineration is one such example.
• Promote Sustainable Transport: Encouraging the use of cleaner modes of power generation, such as electric vehicles, and prioritising rapid urban transit, walking, and cycling networks can help reduce vehicle exhaust emissions.
• Expand and Upgrade Mass Transit Systems: Investing in efficient mass transit systems can reduce the number of private vehicles on the road, thereby lowering vehicle exhaust emissions.
• Reduce Sulfur Content in Fuel: Lowering the sulfur content in fuel can help decrease air pollution levels, especially from power plants and factories.
• Address Climate Change: Climate change exacerbates certain forms of air pollution, such as mold and allergens from trees, weeds, and grass. By addressing climate change through interventions like reducing carbon dioxide emissions, we can indirectly improve air quality.
• Public Awareness and Advocacy: Educating the public about air pollution risks and providing tools like the Air Quality Index (AQI) can empower individuals to take protective measures during high-pollution periods. Additionally, advocating for stronger pollution control measures to local officials can drive policy changes.

These interventions require coordinated efforts from policymakers, industries, and communities to effectively reduce pollution and protect public health.

Frequently asked questions