Air Pollution's Real Impact: A Case Study

Air pollution is a pressing issue that poses significant risks to both public health and the environment. According to the World Health Organization (WHO), approximately 6.7 million premature deaths occur annually due to the combined effects of ambient and household air pollution. This issue is particularly prevalent in low- and middle-income countries, with 89% of premature deaths occurring in these regions. A notable real-life event highlighting the impact of air pollution is the 2019 bushfires in Sydney, Australia. The city experienced historically low air quality due to the smoke and ash from the fires, causing respiratory issues and other health concerns for its residents. This incident serves as a stark reminder of the detrimental effects of air pollution on human health and the environment, emphasizing the urgency to implement effective policies and solutions to combat this global challenge.

The Clean Air Act

The National Ambient Air Quality Standards (NAAQS) program is one of the most important regulatory programs under the CAA. It sets standards for the concentrations of certain pollutants in outdoor air, such as ground-level ozone, carbon monoxide, particulate matter, lead, sulfur dioxide, and nitrogen dioxide. The goal was to set and achieve NAAQS in every state by 1975 to address the health and welfare risks posed by widespread air pollutants.

The 1990 amendments to the Clean Air Act were significant. They aimed to curb four major threats to the environment and public health: acid rain, urban air pollution, toxic air emissions, and stratospheric ozone depletion. The CAA ozone program, for example, phases out the use of chemicals that harm the ozone layer. The 1990 amendments also established a national operating permits program and strengthened enforcement to ensure better compliance.

Climate change and health

Climate change and air pollution have a bidirectional relationship with human health. The combustion of fossil fuels, for example, is a significant contributor to both air pollution and greenhouse gas emissions, which, in turn, negatively impact human health.

Air pollution is defined as the contamination of the indoor or outdoor environment by any chemical, physical, or biological agent that modifies the natural characteristics of the atmosphere. It encompasses a range of pollutants, including particulate matter, carbon monoxide, ozone, nitrogen dioxide, and sulfur dioxide. These pollutants have been linked to various adverse health outcomes, such as respiratory infections, heart disease, lung cancer, and acute and chronic respiratory diseases. According to the World Health Organization (WHO), air pollution, both indoor and outdoor, is responsible for approximately seven million deaths worldwide each year. Vulnerable populations, including children, the elderly, low-income communities, and indigenous peoples, are at a disproportionately higher risk of suffering climate-related health effects.

One notable real-life event that illustrates the impact of air pollution on health is the Great Smog of London in 1952. For four days, the city was engulfed in a thick layer of smog, primarily due to coal combustion. This event led to the premature death of an estimated 12,000 people and caused respiratory infections in over 100,000 individuals. The Great Smog highlighted the deadly consequences of air pollution and prompted the adoption of the Clean Air Act in 1956, which aimed to tackle industrial air pollution.

Another example is the temperature inversion in the Meuse Valley of Belgium, which caused an increase in the concentration of pollutants emitted from industries along the Meuse River. This resulted in the death of about 60 people and sickened 6,000 more. Similarly, in Donora, Pennsylvania, USA, a temperature inversion in 1948 led to the deaths of 20 people and affected the health of 7,000 others due to air pollutants emitted from local industries.

Climate change also influences the prevalence and severity of pollen allergies. Studies have shown that pollen-producing plants, particularly ragweed, thrive and produce more pollen when exposed to higher levels of carbon dioxide. Additionally, climate change prolongs the pollen production season, further exacerbating allergies and triggering asthma attacks, which can be life-threatening.

Furthermore, certain disasters, such as earthquakes, volcanic eruptions, and wars, contribute to air pollution by disturbing air quality and releasing toxic gases. These events can have both immediate and long-term impacts on human health, as seen with the spread of the SARS coronavirus, which caused 775 deaths and 8,096 cases across 37 countries in 2003.

Addressing air pollution and mitigating climate change are crucial for safeguarding public health. The Clean Power Plan, announced by President Obama and the EPA in 2015, is a notable initiative aimed at reducing carbon pollution from power plants. By setting standards for power plants and customized goals for states, the plan strives to reduce carbon pollution and drive the transition to cleaner energy sources.

The ozone layer

In the 1980s, it was discovered that the ozone layer was being depleted by chlorofluorocarbons (CFCs) and other ozone-degrading chemicals released by industries. This depletion occurred at a faster rate than ozone could be naturally created, leading to concerns about the increased UV radiation reaching the Earth. As a result, international efforts, such as the 1987 Montreal Protocol, were implemented to reduce the consumption of ozone-depleting substances.

While there has been a significant reduction in the use of these substances, the ozone hole has persisted, and its behaviour has been influenced by complex interactions of chemical and meteorological factors. For example, volcanic eruptions and wildfires can inject aerosols and smoke-charged vortices into the stratosphere, facilitating ozone depletion. The largest historical extent of the ozone hole occurred in September 2000, covering an area of 28.4 million square kilometres.

Researchers project that the global stratospheric ozone layer will recover to 1980 levels by around 2040. However, the increasing frequency and intensity of wildfires driven by global warming pose additional risks to this fragile layer. Continued global efforts to reduce ozone-depleting substances and mitigate climate change are crucial to ensuring the recovery of the ozone layer.

Air pollution and COVID-19

The COVID-19 pandemic has brought the world to a standstill, with countries adopting partial or complete lockdown protocols to curb the spread of the virus. This unprecedented situation has provided a unique opportunity to study the impact of reduced human activity on the environment, especially air pollution.

During the initial months of the pandemic, global road travel and commercial flight activity decreased by 50% and 60% respectively, with flight activity near a standstill at 96% reduction. This drastic drop in mobility resulted in a significant decline in air pollution levels worldwide. Ultrafine particle concentration, specifically PM2.5, decreased by nearly 50% due to the halt in aviation and road transportation.

Several studies have examined the relationship between air pollution and COVID-19 outcomes. Research has shown that long-term exposure to air pollution can impair the immune system, increasing susceptibility to viral infections. Higher air pollution exposure is associated with higher rates of heart disease and metabolic disorders such as diabetes, which are risk factors for severe COVID-19 illness. A study by Tanaka found that counties with more downwind pollution from power plants experienced higher COVID-19 mortality rates, with a 45% higher cumulative rate during the third mortality peak in January 2021.

Furthermore, a Harvard study linked small increases in long-term exposure to air pollution with significant increases in Americans' risk of death from COVID-19. This was further supported by a deeper analysis by the Tulane Environmental Law Clinic, which found that residents in Louisiana's industrial corridor, nicknamed "Cancer Alley," faced some of the worst impacts of the connection between air pollution and COVID-19 mortality.

The COVID-19 pandemic has highlighted the urgent need to address global air pollution through sustainable local and national policies. The dramatic reduction in air pollution during the pandemic has likely contributed to reducing morbidity and mortality from non-communicable diseases, emphasizing the importance of improving respiratory health and equity worldwide.

Air pollution in Sydney, Australia

Australia has an established "fire season", and the 2019-2020 wildfires were particularly severe. This was due to a particularly dry and hot spell, which may be linked to the broader trend of increasing global temperatures caused by climate change. Bushfires are often started naturally by lightning strikes or accidentally through human-made sparks, while others are started deliberately, either as part of planned hazard reduction strategies or maliciously, through arson. In addition to fires and other natural pollution events, major year-round sources of Sydney's air pollution include motor vehicle exhausts (particularly nitrogen dioxide and PM2.5) and power stations (PM2.5). Wood heaters and road vehicles were the biggest sources of air pollution in Sydney, according to a study using 2013 data. Coal mining was found to be responsible for about 50% of industrial emissions across the region, although this may be outdated as coal power generation has declined by nearly 20% in the last decade.

The main pollutants of concern in Sydney are particulate matter and ozone, which often exceed national standards. In 2019, Sydney's annual average PM2.5 concentration was 10.1 μg/m3, exceeding both Australian and WHO target limits. The WHO guidelines, updated in 2021, recommend exposure to average PM2.5 levels of less than 5 micrograms per cubic metre over a year. These fine particles can be inhaled and enter the bloodstream, causing heart and lung disease. The elderly, children, and people with previous heart and lung problems are considered most at risk. Different studies on the health impacts of air pollution in Sydney estimate that residents' exposure to air pollutants in the city contributes to 1.6-2.9% of total annual fatalities. A more recent study in 2023 estimated that air pollution in NSW caused 603 premature deaths and cost $4.8 billion a year.

Australia's air quality management system is governed at both the national and local levels. The National Environmental Protection Measure for Ambient Air (NEPM) was implemented in 1998 and sets standard targets for seven key air pollutants: carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter (PM2.5 and PM10), and sulphur dioxide. Local governments, such as in New South Wales, also play a role in managing air quality and reducing its adverse effects.

Natural disasters such as earthquakes, wars, and volcanic eruptions can also add to air pollution. For example, a temperature inversion in the Meuse valley of Belgium led to an increased concentration of pollutants emitted from industries, resulting in the death of about 60 people and the sickness of 6,000. Similarly, disasters like bushfires can disturb air quality for a long or short period, and the release of toxic gases in industrial accidents can have unpredictable impacts on human health and the environment.

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