How to monitor Air Pollution from space?
Air pollution has become one of the biggest challenges for modern cities. The increase in concentrations of particulate matter (PM), nitrogen oxides (NO₂), tropospheric ozone(O₃), sulfur dioxides (SO₂), and benzo(a)pyrenes negatively affects the health and well-being of all polluted regions. It is also a huge threat to biodiversity and the functioning of the ecosystems. Reports by the World Health Organisation (WHO) and the European Environment Agency (EEA) warn about serious health effects related to exposure to pollutants, indicating a reduction in life expectancy and an increase in the number of premature deaths.
One year - the average decrease in life expectancy in Europe due to PM exposure, according to WHO data.
Nitrogen Oxides (NOx) mainly come from anthropogenic combustion processes (including transportation, energy production, and other industrial activities). These oxides are highly toxic at high concentrations on the surface. According to the European Environment Agency (EEA) report in 2018, there were 55,000 premature deaths due to NO₂ in Europe, considered one of the most dangerous air pollutants. It is responsible for respiratory diseases, cardiovascular diseases, weakening of lung immune functions, asthma, etc
In the European Union, specific norms for pollutant concentrations aim to protect human health and the environment. The World Health Organization has set even more restrictive levels, emphasizing the need for global action to improve air quality. Enhancing air quality requires the commitment of both authorities and individuals. Reducing traffic, proper planning and management of city green areas, promoting eco-friendly transport, investing in pollution-reducing technologies, and daily decisions to choose public transport or bicycles over cars are key steps towards cleaner air.
In the European Union:
NO₂ - 200 µg/m³ (hourly),
O₃ - 120 µg/m³ (eight-hourly),
SO₂ - 125 µg/m³ (daily).
For comparison, the World Health Organization has set the following permissible concentration levels:
NO₂ - 25 µg/m³ (daily),
O₃ - 100 µg/m³ (eight-hourly),
SO₂ - 40 µg/m³ (daily),
CO - 4 mg/m³ (daily).
What Determines Pollution Levels?
Air quality is determined by the relationship between pollutant emissions and weather conditions. It is estimated that meteorological factors play approximately 70% of the impact on the concentration of pollutants in the atmosphere. Thermal influence on the level of pollution is the length and intensity of the heating season and, for example, the intensity of car traffic. Weather conditions, i.e. air temperature and wind, determine the spread and accumulation of pollutants.
Author: Maciej Jurzyk | Oasis City Lab 13.02.2024
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Standards and Regulations
High nitrogen concentrations harm ecosystems due to eutrophication and acidification, along with sulfur dioxide (SO₂). This leads to changes in species diversity, reducing the number of existing species and enabling the invasion of new ones, as well as increasing pollutant concentrations in soil and water.
In this context, monitoring the spatial distribution of NO₂ is essential for detecting and mitigating high concentrations of this substance in the atmosphere. Besides in-situ measurements, other data sources are needed. This creates a significant demand for satellite data, enabling timely collection of air pollution information in spatial distribution. Therefore, the use of spatial data and satellite data sources is key to better understanding and addressing threats.
How does Sentinel-5P measure air pollution?
In response to global environmental challenges, the Copernicus Earth Observation Program developed the TROPOspheric Monitoring Instrument (TROPOMI), placed on the Sentinel-5 Precursor satellite. The satellite is in a heliosynchronous polar orbit at an altitude of 804 km. It allows for the measurement of Earth's radiation in the NO₂ absorption band with a resolution that enables accurate monitoring of pollutants including NO₂, SO₂, CO, CH₄, CH₂O, and aerosols, as well as surface UV radiation.
TROPOMI obtains information about the concentration of NO₂ in the atmosphere by measuring sunlight scattered back through the atmosphere and the Earth's surface. Due to its high spatial resolution, currently 5.5 x 3.5 km, TROPOMI observations are designed to monitor pollution emission sources at the city/region level and to monitor Earth's climate changes.
These data, collected daily since mid-2018, are essential for fully understanding the spatial distribution of pollutants and tracking their changes over time. Research allows for the development of strategies and the implementation of appropriate remedial measures. As a result, it improves safety related to exposure to the negative and long-term effects of air pollution.
Learn more about the Sentinel-5P mission
Monitoring air pollution with satellite technology is a valuable tool in the fight for a better quality of life in cities. Precise data obtained from satellites enable effective planning of actions aimed at reducing pollution and protecting public health. International cooperation and local initiatives to increase public awareness and data and technology integration are key to achieving lasting improvements in air quality.
Threats to the Natural Environment
Ialongo I et al; Comparison of TROPOMI/Sentinel-5 Precursor NO2 observations with ground-based measurements in Helsinki’, 2020
Grzybowski P et al.; ‘Estimations of the Ground-Level NO2 Concentrations Based on the Sentinel-5P NO2 Tropospheric Column Number Density Product, 2023,
https://www.eea.europa.eu/publications/air-quality-in-europe-2020-report Banse, L; On shooting polar bears: communicating climate change visually.
EUSPA Market report 2023
Smog IMGW: http://smog.imgw.pl/content/weather
Scientific basis and sources:
