Air Quality Alert: Pollutants In Our Air Supply

Air pollution is a significant health and environmental issue worldwide, causing around 7 to 8 million deaths annually. It is caused by the presence of harmful substances in the air, including gases, small particles, and chemicals. These pollutants come from various sources, such as industrial processes, fossil fuel burning, transportation, construction, and agriculture. The specific pollutants in the air vary from place to place and include well-known toxins like lead, mercury, and asbestos, as well as less obvious ones such as formaldehyde from building materials and perchloroethylene from dry cleaning facilities.

Particulate matter

The composition of particulate matter that causes visual effects, such as haze, typically includes sulfur dioxide, nitrogen oxides, carbon monoxide, mineral dust, and organic matter. The presence of sulfur in these particles leads to their hygroscopic nature, and they are converted to sulfates under conditions of high humidity and low temperature, resulting in reduced visibility and the appearance of red, orange, or yellow colours.

The regulation of particulate matter emissions varies across the world. While most industrialized countries have stringent regulations, the enforcement of ambient air quality standards and the reduction of emissions of pollutants that form particulate matter are crucial steps in mitigating its harmful effects.

Burning fossil fuels

One of the primary pollutants released from burning fossil fuels is carbon dioxide (CO2), a greenhouse gas. Greenhouse gases, including CO2, trap heat in the Earth's atmosphere, leading to global warming and climate change. The combustion of fossil fuels has already contributed to a 1°C increase in global average temperatures, and the consequences are far-reaching. These include rising sea levels, more frequent and severe extreme weather events, biodiversity loss, species extinction, and food scarcity, all of which pose significant threats to human societies and natural ecosystems.

In addition to CO2, the burning of fossil fuels emits a range of other harmful substances. These include nitrogen oxides (NOx), which contribute to the formation of smog and acid rain, and particulate matter, which consists of tiny solid or liquid particles such as soot, dust, smoke, and fumes. These particles, especially those smaller than 2.5 micrometres (PM2.5), pose a significant health risk as they can be inhaled and penetrate deep into the lungs, entering the bloodstream and causing cardiopulmonary and respiratory issues. Exposure to these pollutants has been linked to an increased risk of stroke, heart disease, chronic obstructive pulmonary disease (COPD), asthma, and lung cancer.

The impact of burning fossil fuels on air pollution is particularly notable in the transportation sector. Vehicles with petrol and diesel engines contribute significantly to air pollution, with approximately half of their emissions coming from exhaust gases and the other half from non-exhaust sources such as tyre and brake wear. Additionally, diesel trains, ships, and planes also contribute to air pollution. The manufacturing and construction sectors are also major contributors, as highlighted by a 2014 study in China, which found that these industries were responsible for over 50% of the country's air pollution due to their high emission intensity and emission factors.

Overall, the burning of fossil fuels has far-reaching consequences for human health, the environment, and the climate. It is a significant contributor to the global disease burden, not only causing premature deaths but also reducing the quality of life for many people, especially those in urban areas, children, older individuals, low-income communities, and people of colour. Addressing this issue requires a transition to renewable energy sources, improved air quality standards, and the implementation of effective policies and technologies to reduce air pollution and mitigate its impacts.

Construction and demolition

Demolition activities can release various types of dust and fine particles into the air, which can remain suspended for extended periods, depending on weather conditions. This dust may contain toxic materials such as asbestos, lead, and other respiratory irritants like bird waste and mould. Asbestos, in particular, poses serious health risks, with its fibres and dust potentially causing mesothelioma, lung cancer, and asbestosis. The demolition of older buildings with asbestos-containing materials requires careful management to prevent the release of these hazardous substances.

The use of heavy machinery in construction and demolition also contributes to air pollution. These machines often run on diesel fuel, emitting pollutants such as nitrogen oxides (NOx) and carbon monoxide (CO). Carbon monoxide is especially dangerous due to its invisible, odourless nature, making it a silent killer. Machinery combustion products, including diesel exhaust, can contain carbon dioxide, sulphur and nitrogen compounds, further degrading air quality.

In addition to outdoor air pollution, construction and renovation projects in occupied buildings can introduce indoor air quality issues. Volatile organic compounds (VOCs), released from paints, adhesives, roofing materials, and other construction products, can accumulate indoors, posing health risks to occupants. Fossil fuel-powered equipment used during renovations can also release combustion products, such as carbon monoxide, into occupied spaces.

The impact of construction and demolition on air pollution is significant, with the construction sector contributing substantially to particulate matter (PM10 and PM2.5) and nitrous oxide emissions. Construction waste, if not properly managed, can lead to increased airborne pollutants, further degrading air quality. To mitigate these issues, it is crucial to implement efficient waste reduction strategies, adopt low-emission machinery, and prioritize the use of environmentally friendly construction practices and technologies.

Road vehicles

The transportation sector is a major source of heat-trapping emissions, with vehicles emitting more than half of the nitrogen oxides in the air. Heavy-duty vehicles, such as trucks and buses, are of particular concern. They make up only about 10% of all vehicles on the road but contribute to a much larger percentage of global warming emissions, NOx emissions, and PM2.5 emissions. Exposure to these pollutants is inequitable, with Latinos, Blacks, and lower-income households bearing a disproportionate burden.

To address this issue, governments and organizations have implemented various strategies. The US government has imposed tougher emissions standards, and consumers are increasingly demanding better fuel efficiency. The deployment of zero-emissions trucks and the electrification of the on-road freight system are being prioritized to reduce pollution and improve air quality. The EPA has also developed resources like the Green Vehicle Guide to help consumers make more environmentally-conscious choices when purchasing a vehicle.

Additionally, individuals can make a difference by choosing the most fuel-efficient vehicle that meets their needs, maintaining their vehicles properly, and reducing the number of miles driven. Walking, biking, carpooling, or utilizing public transportation are all effective ways to decrease an individual's carbon footprint and contribute to cleaner air.

Toxic metals

Some of the oldest cases of environmental pollution were caused by the extraction and use of heavy metals. For example, the Romans' mining, smelting, and utilisation of copper, mercury, and lead. The amounts of most heavy metals deposited on the surface of the Earth from anthropogenic activities are many times greater than those from natural background sources. Combustion processes are the most important sources of heavy metals, especially power generation, smelting, incineration, and internal combustion engines.

The European Union's Dangerous Substances Directive defines dangerous chemicals as those that are toxic, persistent, and/or bioaccumulative. The EU has set critical levels for heavy metals in agricultural soils that receive sewage sludge. The Environmental Protection Act of 1990 requires Environmental Quality Standards (EQSs) for chemicals in water, and EQS values for mercury and cadmium are available.

In the United States, the Environmental Protection Agency (EPA) has established health-based National Emission Standards for Hazardous Air Pollutants (NESHAPs), addressing more than 180 air toxics. These include heavy metals such as cadmium, chromium, lead, and mercury. Short-term exposure to these toxic metals can lead to eye irritation, nausea, or difficulty breathing.

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