6. Air Quality Monitoring and Measurement

6.1. Air Quality Monitoring Stations

Air quality monitoring stations are fixed points equipped with scientific measuring devices used to detect the levels of harmful pollutants in the atmosphere and track changes in these levels over time. These stations continuously monitor the concentration of key pollutants such as particulate matter (PM10, PM2.5), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), carbon monoxide (CO), and ozone (O₃).

Modern air quality monitoring systems also measure parameters such as humidity, temperature, wind direction, and speed, along with meteorological data, enabling the analysis of the causes and effects of air pollution. Monitoring stations are typically located in industrial areas, at intersections with high traffic density, or in the centers of residential areas. This enables the creation of regional pollution maps and the analysis of air quality levels.

The Black Sea Basin countries are monitoring transboundary air pollution through regional cooperation by developing their environmental monitoring infrastructure and providing data support for decision-making processes. The data obtained is shared with the public through air quality indices published by national environmental agencies and relevant municipalities, and measures to be taken for public health are shaped accordingly.

Advanced monitoring networks have been established in Black Sea Basin countries to continuously monitor and assess air quality:

Romania: The network managed by the National Environmental Protection Agency (ANPM) consists of over 150 fixed stations. These stations monitor pollutants such as PM10, PM2.5, NO₂, SO₂, CO, and O₃ in accordance with European Union directives.
Bulgaria: The system managed by the Bulgarian Ministry of Environment and Water consists of approximately 60 fixed stations. The public can access air quality data through the National Environmental Monitoring System.
Türkiye: The National Air Quality Monitoring Network (UHKIA), operated by the Ministry of Environment, Urbanization, and Climate Change, consists of over 380 fixed stations across 81 provinces. Real-time data is available at https://www.havaizleme.gov.tr
Ukraine: The State Ministry of Ecology and Natural Resources conducts continuous measurements through stations established in major cities (Kyiv, Odessa, Lviv). Additionally, infrastructure investments aimed at strengthening air quality management have been increased in recent years.

These international collaborations are of critical importance for monitoring transboundary pollution and developing regional strategies.

6.2. Air Quality Monitoring via Satellite Observations

Satellite-based monitoring systems provide the ability to observe air quality over a wide geographical area and provide valuable information in areas that are inaccessible to traditional measurement stations. Thanks to remote sensing technology, particles, greenhouse gases, and gaseous pollutants in the atmosphere can be analyzed, enabling more comprehensive environmental assessments.

MODIS is a multispectral imaging sensor developed by NASA and installed on the Terra (1999) and Aqua (2002) satellites. Capable of measuring in 36 different spectral bands, this sensor has a spatial resolution ranging from 250 meters to 1 kilometer and passes over the same area twice a day, providing high temporal resolution.

MODIS’s most significant contribution to air pollution monitoring is the determination of aerosol optical depth (AOD) values in the atmosphere. AOD is a parameter that indicates how much sunlight is absorbed or scattered by aerosols (particles such as dust, smoke, and soot) in the atmosphere. Since there is a high correlation between surface-based PM2.5 measurements and AOD, MODIS data is used to estimate PM2.5 concentrations in areas where station data is unavailable or insufficient.

MODIS also enables the assessment of atmospheric conditions such as active fire detection, surface temperature measurement, cloud cover, and moisture profile. MODIS data products such as MOD14 and MYD14 are widely used for monitoring sudden air pollution events such as forest fires and dust storms. The Sentinel-5P satellite is a dedicated mission launched under the Copernicus Program, operated by the European Space Agency (ESA), for air quality monitoring.

Sentinel-5P (Precursor) was launched by the European Space Agency (ESA) in 2017 as part of the Copernicus program. This satellite carries a sensor called TROPOMI (Tropospheric Monitoring Instrument), which was developed to measure tropospheric air pollutants with high spatial and spectral resolution.

TROPOMI is capable of detecting the following pollutants:

NO₂ (Nitrogen dioxide): Primarily produced by traffic and industrial sources. TROPOMI can monitor it with high accuracy at the city level.
CO (Carbon monoxide): Released as a result of fossil fuel combustion and forest fires.
O₃ (Ozone): Tropospheric ozone acts as a pollutant at ground level.
SO₂ (Sulfur dioxide): Originates from thermal power plants and volcanic activity.
CH₄ (Methane): Associated with agricultural activities and fossil fuel production.
Aerosol Absorbing Index: Indicates the optical density of particulate sources such as dust transport and smoke.

Sentinel-5P provides data at a resolution of 3.5 km x 5.5 km, enabling the creation of distribution maps for gases such as NO₂ that vary at the urban level. This level of detail makes it possible to observe urban air pollution in detail from space. The satellite passes over specific regions at the same time every day, providing daily measurements. The integration of Sentinel-5P data is strategically important for air quality management in regions with large and diverse geographical structures, such as the Black Sea Basin. These data provide scientific support to decision-makers in the fight against air pollution.

Monitoring air pollution from space enables the tracking of harmful gases and particulate matter in the atmosphere, contributing to environmental decision-making processes at both regional and global scales. There are other important satellite missions besides MODIS and Sentinel-5P.

1. OMI (Ozone Monitoring Instrument) – NASA / KNMI

(Netherlands) Satellite: Aura (EOS) – NASA

Launch Year: 2004

Spectral Bands: 270–500 nm (UV and visible bands)

Spatial Resolution: 13,× , 24 km (13,× , 13 km in high-resolution mode)

OMI is a UV-Visible spectrometer capable of measuring the tropospheric and stratospheric ozone layer, as well as gases such as nitrogen dioxide (NO₂), sulfur dioxide (SO₂), carbon monoxide (CO), and formaldehyde (HCHO). OMI also provides data on UV radiation, aerosol indices, and cloud cover.

Technically, OMI’s imaging (push-broom) scanning system covers a large area in a short time, providing daily global coverage. OMI’s NO₂ and SO₂ measurements are frequently used to analyze temporal changes in urban emissions.

OMI data have served as a primary reference in many studies prior to Sentinel-5P and are still used as a historical dataset for long-term air quality analysis.

2. GOME-2 (Global Ozone Monitoring Experiment – 2) – EUMETSAT

Satellite: MetOp -A, -B, -C

Launch Years: 2006 (A), 2012 (B), 2018 (C)

Spectral Range: 240–790 nm

Spatial Resolution: 40,× , 40 km

GOME-2 is a spectrometer operating in the UV and visible spectrum, measuring ozone, NO₂, SO₂, BrO (bromine dioxide), HCHO, aerosol indices, and cloud properties in the atmosphere. GOME-2 data are particularly suitable for researchers seeking long-term observations at medium resolution.

Thanks to its NO₂ and SO₂ monitoring capabilities, regional mapping of pollution from coal-fired power plants can be performed. It is also widely used for tracking volcanic emissions.

3. VIIRS (Visible Infrared Imaging Radiometer Suite) – NOAA/NASA

Satellite: Suomi NPP and NOAA-20

Launch Years: 2011 (Suomi NPP), 2017 (NOAA-20)

Spectral Bands: 22 bands (visible and thermal infrared)

Spatial Resolution: 375 m and 750 m (dual resolution system)

VIIRS monitors various parameters such as aerosol optical depth (AOD), surface temperature, active fires, albedo, and nighttime lights. As the successor to MODIS, this system provides high-resolution imagery with more advanced sensors.

AOD measurements are used for indirect estimation of PM2.5 distribution. Additionally, it provides detailed analyses on wildfire smoke dispersion, urban heat island effect, and urban pollution density.

4. CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) – NASA / CNES

Launch Year: 2006

Sensor: LIDAR+ IR imager

Spatial Resolution: Vertical profile resolution 30 m (lower atmosphere)

CALIPSO is a specialized satellite mission that uses LIDAR technology to measure the vertical profile of cloud and aerosol distribution in the atmosphere. This feature provides information about particle concentrations at heights that cannot be obtained using other passive sensors.

For example, it can detail the altitudes at which dust from the Sahara is transported during dust transport events. Additionally, the layer in the troposphere where smoke from industrial areas spreads can be tracked.

5. TEMPO (Tropospheric Emissions: Monitoring of Pollution) – NASA (Scheduled for launch soon)

Planned Launch: 2025

Purpose: Hourly monitoring of tropospheric air pollution in the United States and surrounding areas

Feature: The first air pollution satellite sensor to operate in a geostationary orbit

TEMPO’s biggest innovation is its ability to monitor a specific area hourly throughout the day. This will enable the tracking of short-term changes caused by factors such as traffic and energy consumption during the day. The data can be integrated with location-based sensors to evaluate the effectiveness of measures taken against air pollution.

Different satellite missions measure air pollution parameters using various technical methods and resolution levels. This data is used for the following primary purposes:

PM2.5 and PM10 estimates (MODIS, VIIRS, CALIPSO)
Gas-based emission mapping (OMI, Sentinel-5P, GOME-2)
Fire, smoke, and dust transport monitoring (MODIS, VIIRS, CALIPSO)
Analysis of pollution sources by altitude (CALIPSO)
Policy impact and time series analysis (OMI, GOME-2)

The data from these satellite systems is critical for identifying health risks associated with air pollution, establishing early warning systems, monitoring emission policies, and conducting academic research.

6.3. Mobile Applications and Real-Time Monitoring

Thanks to mobile applications and portable sensor technologies, it is possible to access air quality data in real time. Today, mobile applications developed by both public institutions and the private sector provide users with air quality indices for their current location, thereby enabling individuals to make informed decisions.

These applications process data obtained from stations and satellites to provide AQI (Air Quality Index) scores; they also include features such as historical data analysis, detailed graphs based on pollutants, and health alerts. This information plays a critical role in planning daily activities, especially for individuals with respiratory conditions.

Furthermore, citizen-supported monitoring can be conducted in different parts of cities using sensor networks and low-cost portable monitoring devices, enabling data production in areas not covered by official networks. Various mobile platforms and sensor initiatives developed in the Black Sea Basin countries support data-driven policy-making and increase public awareness.

Access to real-time air quality information facilitates individuals’ ability to take precautions against environmental risks; it also contributes to the spread of sustainable living habits by increasing environmental awareness.

Mobile technologies make it easier for individuals to access information about environmental health in real time. Some of the most widely used applications worldwide are:

IQAir – AirVisual

Developer: IQAir (a Swiss-based environmental technology company)

Platform: iOS, Android, and web

Coverage: Over 100 countries, over 10,000 monitoring stations

Data Sources: Official air quality stations, low-cost sensor networks, meteorological data, and AI-powered prediction models

Technical Features:

Air Quality Index (AQI) Display: PM2.5, PM10, NO₂, CO, and O₃ values calculated according to World Health Organization (WHO) standards are visualized.
Real-Time Monitoring: The application provides users with the current air quality status at their location and a forecast for the next 72 hours.
Health Recommendations: Provides recommendations for sensitive groups such as the elderly, children, and asthma patients based on pollutant levels.
Global Air Quality Map: An interactive map allows users to compare pollution levels across different cities.
Personalized Alerts: Automatically notifies users when the Air Quality Index (AQI) exceeds critical thresholds.

Usage Benefits:

Makes it easier to plan daily activities (such as exercise or outdoor time) based on air quality.
Provides global awareness of air quality for travelers.

Plume Labs – Air Report

Developer: Plume Labs (France)

Platform: iOS, Android

Coverage Area: 70+ countries, thousands of sensor locations

Data Sources: Official government stations, low-cost user-based sensor devices, predictive modeling