How Satellites Monitor Pollution From Space

The burning of satellites and other spacecraft in the atmosphere releases harmful chemicals, which can remain in the atmosphere for decades or even centuries. Nitrogen dioxide (NO2), a key component of urban air pollution, is one such chemical. The COVID-19 pandemic provided a unique opportunity to study the impact of reduced human activity on air pollution. For instance, the NOAA's polar-orbiting satellites observed a dramatic reduction in air pollution in the US as vehicular traffic decreased significantly during the pandemic.

Satellites can indeed help us see pollution. For example, the Sentinel-5P satellite showed higher NO2 pollution in March 2019 compared to March 2020 in regions with typically high NO2 emissions, such as Los Angeles, San Francisco, and Chicago.

However, the increase in satellites and space debris is also contributing to light pollution, which poses a significant threat to ground-based astronomy and our ability to observe the night sky. The number of functional satellites in low-Earth orbit has more than doubled since 2019, and there are plans to launch up to 100,000 more within the next few years. This has led to concerns about the potential impact on the detection of potentially dangerous near-Earth asteroids and other astronomical observations.

To address these issues, solutions such as recoverable satellites, space debris recycling, and engineered reentries are being proposed. For instance, the UK startup Space Forge is working on large foldable heat shields that can protect satellites during reentry, allowing for their recovery, refurbishment, and relaunch. Additionally, companies like Neumann Space are exploring the idea of recycling space junk, particularly aluminum alloys, as fuel for electric propulsion systems.

Satellites can identify the main air pollutants: ozone, nitrogen dioxide, sulphur dioxide and particulate matter

Satellites are able to identify the main air pollutants: ozone, nitrogen dioxide, sulphur dioxide and particulate matter.

Nitrogen dioxide (NO2) is a key component of air pollution, particularly in urban areas. It is emitted by cars, trucks, and other vehicles, as well as power plants and industrial facilities burning fossil fuels. Using instruments on the NOAA/NASA Suomi-NPP satellite and the European Space Agency's (ESA) Sentinel-5P satellite, scientists are able to observe NO2 emissions and monitor their changes over time. For example, during the COVID-19 pandemic, a significant reduction in NO2 emissions was observed in typically high-emission regions across the US due to decreased vehicular traffic.

Sulphur dioxide (SO2) is a regulated air pollutant and health hazard that contributes to acid rain. Satellites, such as NASA's Aura spacecraft, have been instrumental in locating previously unreported sources of SO2 emissions, which appear as "hot spots" in satellite images. This information is crucial for developing comprehensive emissions inventories and guiding regulatory policies for air quality management.

Ozone, while naturally occurring in the upper atmosphere, can be a harmful pollutant at ground level. It is often formed when nitrogen dioxide reacts with other chemicals in the atmosphere. Satellites like NASA's Aura, equipped with the Dutch-Finnish Ozone Monitoring Instrument (OMI), play a vital role in monitoring ozone levels and identifying areas of concern.

Particulate matter, or airborne particles, is another type of air pollution that satellites help monitor. The Suomi-NPP satellite, for instance, has been used to observe airborne particulate pollution and assess its changes in relation to NO2 emissions. By comparing data from different years and between weekdays and weekends, scientists can gain insights into the impact of human activity on particulate matter pollution.

In summary, satellites provide valuable data and imagery that help identify and monitor the main air pollutants, including ozone, nitrogen dioxide, sulphur dioxide, and particulate matter. This information is essential for understanding air quality, tracking pollution sources, and informing policies to improve the health and well-being of people and the planet.

Orbital satellites can monitor air pollution levels and how they change during COVID lockdowns

Orbital satellites have been used to monitor air pollution levels and how they changed during COVID lockdowns. A joint study by the United Nations Development Programme (UNDP) and the European Space Agency (ESA) used satellite data to understand air pollution in the Republic of Moldova and Ukraine. The study, called "COVID-19 Impact on Air Quality in Ukraine and the Republic of Moldova", found that while the lockdown caused a serious economic downturn and led to cleaner air in some regions, the overall change in air pollution data was not considerable.

The research team used satellite data provided by Sentinel 5P to analyse the main air pollutants: ozone (O3), nitrogen dioxide (NO2), sulphur dioxide (SO2) and particulate matter (PM10 and PM2.5). They found that pollution hotspots were in cities with heavy industry, and that particulate matter can affect a wider geographical range as it is carried by the wind.

In Ukraine, air pollution is one of the three major environmental concerns of the population. The research team was able to spot major polluted areas based on particulate matter concentrations in the 3 years of observation, and also detected a reduction of air pollution concentrations during the COVID-19 lockdown.

Similarly, in the US, NOAA’s Polar-Orbiting Satellites observed a drop in air pollution levels during the COVID-19 pandemic. Scientists compared NO2 and airborne particulates data from March 2019 (pre-COVID-19) and March 2020 (during COVID-19), and found that the economic slowdown had reduced vehicular traffic, especially for cars, which dropped by about 50% or more nationwide.

Overall, the use of orbital satellites to monitor air pollution levels during COVID lockdowns has provided valuable insights for policymakers and practitioners, helping them to assess the impact of the pandemic on air quality and make informed decisions to improve air quality and protect public health.

Orbital satellites can identify pollution hotspots and the regions most vulnerable to air pollution

Orbital satellites can indeed identify pollution hotspots and the regions most vulnerable to air pollution. In fact, they are already being used for this purpose.

The European Space Agency's Sentinel 5P satellite, for example, is equipped with cutting-edge technology for atmospheric measurements. In collaboration with the UNDP Moldova and UNDP Ukraine, the Sentinel 5P was used to analyse the main air pollutants: ozone (O3), nitrogen dioxide (NO2), sulphur dioxide (SO2) and particulate matter (PM10 and PM2.5). The data showed that pollution hotspots were concentrated in cities with heavy industry, with high levels of nitrogen dioxide. Particulate matter was also found to affect a wider geographical range, as it is easily carried by the wind.

The Sentinel 5P satellite has also been used by the National Oceanic and Atmospheric Administration (NOAA) to observe a dramatic reduction in air pollution in the US during the COVID-19 pandemic. By comparing NO2 and airborne particulate pollution data from March 2019 (pre-COVID-19) and March 2020, NOAA scientists were able to attribute the decrease in pollution to the reduction in vehicular traffic.

While satellite data can be incredibly useful for understanding air pollution and identifying vulnerable regions, it should be used in conjunction with locally collected data. This is because satellite data may lack precision or miss pollutants that are more easily recognised at a local level. Combining the two types of data can also help to validate citizen- or state-collected measurements.

Orbital satellites can help inform policy to diminish overall pollution levels and their health impact

Satellites can capture data on air pollution that is invisible to the human eye. This data can be used to inform policy to reduce pollution levels and their impact on health. For example, the data can be used to support a reduction in coal plants and the subsidising of fossil fuels, while focusing on green economy targets and programmes.

During the COVID-19 pandemic, orbital satellites from the National Oceanic and Atmospheric Administration (NOAA) observed a dramatic reduction in the amount of air pollution in the US. This was due to the economic and societal slowdown caused by the pandemic. Scientists used instruments on the NOAA/NASA Suomi-NPP satellite and the European Space Agency's (ESA) Sentinel-5P satellite to look for signals of decreased nitrogen dioxide (NO2) emissions. They found that NO2 concentrations were higher in March 2019 compared to March 2020, with a more discernible reduction on weekends due to reduced traffic.

In addition to helping to monitor air pollution, satellites can also contribute to the identification of pollution hotspots. For instance, the European Space Agency's Sentinel-5P satellite helped identify pollution hotspots in cities with heavy industry, where nitrogen dioxide levels were high. This information can be used to target policies and interventions to reduce pollution levels in these areas.

Furthermore, satellite data can be used to validate citizen-led or state-collected data on air pollution. This can increase confidence in local measurements and inform policy development.

Orbital satellites can help validate citizen- or state-collected data on air pollution

To address these limitations, UNDP Moldova and UNDP Ukraine partnered with the European Space Agency and their EO Clinic program to test the applicability of satellite data to understand air pollution and which regions are most vulnerable. By using satellite data provided by Sentinel 5P, a cutting-edge satellite technology equipped with the latest technologies for atmospheric measurements, the research team analyzed the main air pollutants: ozone (O3), nitrogen dioxide (NO2), sulphur dioxide (SO2), and particulate matter (PM10 and PM2.5). The data showed that pollution hotspots were glaring in cities with heavy industry, and data showed that these emitters might be more significant than other forms of pollution.

Additionally, the data revealed that particulate matter, which is easily carried by the wind, affects a far wider geographical range than just the locations of pollution. At Ukraine's national level, the average annual concentration of PM2.5 of 10 μg/m3 was reached or exceeded in 16 out of 36 months monitored, with higher concentrations observed in the spring and autumn months, which may lead to a 15% increase in mortality. The data also showed that most cities surged on Fridays, and in winters, the country sees almost a tenfold increase in the concentrations of nitrogen dioxide and sulphur dioxide compared to the summer period.

Overall, satellite data can help complement and validate citizen- or state-collected data on air pollution. It can provide a more complete and precise picture of air pollution levels and help inform policies to diminish overall pollution levels and their health impacts.

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