Nasa's Air Pollution: Causes And Concerns

Air pollution is caused by solid and liquid particles and certain gases suspended in the air. These particles and gases can come from car and truck exhaust, factories, dust, pollen, mould spores, volcanoes, and wildfires. NASA uses satellites orbiting Earth to monitor air pollution and has developed a new instrument called the Multi-Angle Imager for Aerosols (MAIA) to help scientists understand the size, makeup, and quantity of aerosols in our air. According to a study published in the British Medical Journal (BMJ), air pollution from fine particulates and ozone causes the premature death of 8.3 million people every year.

Burning fossil fuels

One of the primary pollutants produced by burning fossil fuels is nitrogen dioxide (NO2). Cars, trucks, and other vehicles are a major source of nitrogen dioxide as a byproduct of fossil fuel combustion. High levels of this pollutant are typically found near roadways and infrastructure in urban areas. It is a pungent air pollutant that irritates airways and is associated with pediatric asthma.

Another significant pollutant formed through the burning of fossil fuels is ground-level ozone. Ozone is created when sunlight reacts with certain chemicals emitted by sources burning fossil fuels, such as factories and car exhaust. Ground-level ozone is harmful to human health and contributes to smog formation, making it difficult to see outside in heavily polluted cities.

In addition to nitrogen dioxide and ozone, the combustion of fossil fuels releases fine particulate matter, also known as particle pollution. These small particles can be inhaled and lead to respiratory and cardiovascular issues, including heart and lung diseases. They may even cause cancer and congenital disabilities. Reducing the use of fossil fuels is crucial to improving air quality and mitigating the health risks associated with these pollutants.

Furthermore, the burning of fossil fuels contributes to the release of sulphur dioxide (SO2). This pollutant is of particular concern as it can react with water and other gases to create sulphate aerosols, which have a cooling effect on the climate. While SO2 can mask the effects of global warming, it also contributes to acid rain and has detrimental effects on human health. Fossil fuels have been linked to millions of excess deaths annually from air pollution.

Nitrogen dioxide pollution

Nitrogen dioxide (NO2) is a gaseous air pollutant composed of nitrogen and oxygen. It is formed when fossil fuels such as coal, oil, gas, or diesel are burned at high temperatures. NO2 is one of the two principal nitrogen oxides associated with combustion sources, the other being nitric oxide (NO). These nitrogen oxides are colourless gases emitted by industrial processes, vehicles, and power plants.

Long-term exposure to low levels of nitrogen dioxide can lead to various adverse health outcomes. Animal studies have shown that subchronic and chronic exposures to low levels of nitrogen dioxide can cause alterations to lung metabolism, structure, and function, inflammation, and increased susceptibility to pulmonary infections. It can also lead to emphysema-like changes, including destruction of alveolar walls and airspace enlargement, which are characteristics of human COPD.

It is important to note that efforts have been made to reduce nitrogen dioxide pollution. Under the federal Clean Air Act, more protective standards have helped drive down nitrogen dioxide emissions nationwide. Power plants, industrial sites, and on-road vehicles are now cleaner, leading to improved air quality across the nation. However, there is still a significant portion of the population breathing in unhealthy levels of nitrogen dioxide pollution.

Particulate matter

Aerosols can be natural or human-made. According to NASA's Earth Observatory, approximately 9 out of 10 aerosols occur naturally, including sulphates, organic carbon, mineral dust, and sea salt. However, human-made aerosols are of greater concern as they are increasing in amount and are linked to more than 5 million excess deaths a year from air pollution.

One primary source of human-made aerosols is the burning of fossil fuels, such as coal, petroleum, and wood, by cars, power plants, or industrial processes. This produces sulphur dioxide (SO2) which can react with water and other gases to create sulphate aerosols. SO2 is also linked to the formation of acid rain and contributes to the "masking" of global warming.

Another human-made aerosol is black carbon, which is emitted by engines that burn gas and diesel, as well as from the burning of biomass. Black carbon contributes to respiratory and cardiovascular issues and may cause cancer and congenital disabilities. It also has an impact on the climate, as it absorbs light and warms the air. When deposited on ice caps, it accelerates their melting.

Nitrogen oxides (NOx) are another group of air pollutants that contribute to particulate matter. They are colourless gases emitted by industrial processes, vehicles, and power plants. As they react with other chemicals in the atmosphere, they form small particles that can contribute to respiratory diseases and acid rain.

NASA uses satellites to monitor air pollution and study the health impacts of these pollutants on various communities.

Sulphur oxides

SO2 is emitted by power plants, metals processing and smelting facilities, and vehicles. The burning of fossil fuels by power plants and other industrial facilities is the largest source of SO2 in the atmosphere. Diesel vehicles and equipment were once a major source of SO2, but federal regulations to reduce the sulphur content in diesel fuels have significantly lowered emissions.

SO2 and other sulphur oxides can contribute to acid rain, which can harm sensitive ecosystems, waterways, and foliage of trees and plants. Acid rain forms when sulphur dioxide combines with water and air to form sulphuric acid. Acid rain can also damage stone and other materials, including culturally important objects such as statues and monuments.

Additionally, sulphur oxides can react with other compounds in the atmosphere to form small particles that contribute to particulate matter (PM) pollution. These small particles may penetrate deeply into the lungs and, in sufficient quantities, can contribute to respiratory issues, irritate the eyes, and aggravate existing heart and lung conditions such as asthma and chronic bronchitis.

To address the issue of sulphur oxide emissions, the EPA has implemented national and regional rules to reduce SO2 emissions and pollutants that form sulphur oxides. These regulations aim to help state and local governments meet the Agency's national air quality standards.

Black carbon

The health impacts of black carbon are primarily due to its tiny size. When inhaled, black carbon can find its way deep into the lungs and bloodstream, causing cardiovascular and respiratory diseases. According to the World Health Organization, 3.7 million premature deaths in 2012 were attributed to outdoor air pollution, and 4.3 million to indoor air pollution. Black carbon is a critical component of particulate matter pollution, often accounting for between 5-25% of measured PM2.5 concentrations. It is estimated to be the second most important human-emitted climate pollutant after CO2.

NASA researchers are working to better understand the impacts of black carbon on Earth's climate, cryosphere, and clouds. They use satellite data and computer models, such as the GEOS5 GOCART climate model, to study black carbon's atmospheric concentration and distribution. NASA's Terra and Aqua satellites, for example, analyze the optical properties of aerosols to estimate black carbon concentrations. These efforts provide valuable insights into the global distribution and movement of black carbon, complementing ground-level measurements.

Efforts are also being made to curb black carbon emissions. The Climate and Clean Air Coalition, for instance, has developed plans to tackle short-lived climate pollutants, including black carbon, through initiatives such as the Green Freight Action Plan. This plan aims to increase awareness, develop methods for tracking and reporting emissions, and promote technologies and best practices for their reduction.

Frequently asked questions