Air and Water Quality Measurement Technologies

Air and water quality measurement technologies are systems composed of devices, sensors, and analytical methods designed to determine the types, concentrations, and spatial distributions of pollutants in the atmosphere and water sources. These technologies, increasingly important due to the impacts of industrialization, urbanization, and intensive agricultural activities, play a critical role in protecting human health, maintaining the balanced functioning of ecosystems, and ensuring the sustainable management of natural resources.

The main parameters measured in air quality monitoring include particulate matter (PM₂.₅, PM₁₀), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), carbon monoxide (CO), ozone (O₃), and volatile organic compounds. These components are analyzed using fixed monitoring stations, portable sensors, laser-based measurement systems, and remote sensing techniques. Similarly, water quality monitoring technologies measure physical, chemical, and biological parameters such as pH, dissolved oxygen, temperature, turbidity, heavy metals, nutrient salts, and organic pollutants. For this purpose, electrochemical probes, spectrophotometric analysis systems, biosensors, and satellite-based observation techniques are employed.

The data obtained contribute to the development of environmental policies, the assessment of public health risks associated with air and water pollution, the regulation of agricultural and industrial activities, and compliance with national and international environmental standards. The continuous and high-accuracy data provided by these technologies also serve as a fundamental reference point in decision-making processes aimed at tracking environmental trends in the context of climate change and preserving ecosystems.

Air Quality Measurement Technologies

Air quality measurement technologies encompass the full range of methods used to detect, quantify, and evaluate pollutants in the atmosphere. This process forms the foundation of air pollution reduction policies and includes identifying, monitoring, and controlling pollution sources. Air pollution is defined as the presence of harmful gases, particulate matter, and chemical compounds in the atmosphere at levels exceeding established thresholds. Monitoring activities are considered essential both for compliance with national and international legal regulations and for the protection of public health.

Key Pollutants Measured

The primary pollutants targeted in air quality measurements include:

• Particulate Matter (PM): A general term for solid and liquid particles suspended in air; one of the most critical parameters due to its health impacts.
• • PM₁₀: Particles with an aerodynamic diameter smaller than 10 micrometers.
  • PM₂.₅: Fine particles with an aerodynamic diameter smaller than 2.5 micrometers.
  • PM₁.₀: Ultrafine particles smaller than 1 micrometer; pose a high health risk due to their potential to reach deep lung regions and the bloodstream.
  • TSP (Total Suspended Particulate): The total of all particles suspended in air; particularly relevant in construction, mining, and heavy industrial activities.
• Gaseous pollutants:
• • Carbon monoxide (CO)
  • Carbon dioxide (CO₂)
  • Nitrogen oxides (NO, NO₂, NOx)
  • Sulfur dioxide (SO₂)
  • Ozone (O₃)
  • Volatile organic compounds (VOCs)
  • Formaldehyde (HCHO)

Most of these pollutants are released into the atmosphere through human-driven processes such as energy production, industrial operations, transportation, and agricultural activities.

Measurement Methods and Instruments

Different sensors, analyzers, and sampling techniques are used to detect air quality parameters. These systems vary according to the measurement objective, required accuracy, and cost considerations.

• Gas sensors
• • Electrochemical sensors: Used for measuring gases such as CO, NO₂, and O₃; they record changes in electrical current caused by chemical reactions at the electrode surface.
  • Optical sensors: Preferred especially for CO₂ measurement; based on the absorption or scattering of light at specific wavelengths by the gas.
  • Photoionization detectors (PID): Provide high sensitivity for measuring VOCs and petroleum-derived volatile compounds; commonly used in industrial air quality monitoring.
• Particulate matter sensors
• • Laser scattering (dispersion): Analyzes particle size and concentration by measuring how particles scatter laser light.
  • Beta attenuation (Beta Gauge): A widely used method for determining PM₁₀ and PM₂.₅ concentrations.
  • Gravimetric method: Based on weighing particles collected on a filter over a specific period; recognized as the reference method.
• Passive sampling: A low-cost method in which pollutants are adsorbed into absorber tubes via diffusion and later analyzed in the laboratory (e.g., gas chromatography) to determine average pollutant levels.

Monitoring Stations and Systems

Air quality monitoring is carried out at different scales and with varying technological infrastructures.

• Fixed monitoring stations: A traditional method using certified analyzers to provide high accuracy; operated by official authorities. However, installation and operational costs are high, and spatial coverage is limited.
• Movable monitoring stations: Vehicle-based systems used for short-term measurements in specific areas, identifying pollution sources, or creating pollution distribution maps. Equipped with gas analyzers, dust measurement devices, meteorological sensors, and data transmission systems.
• Low-cost sensor networks: Systems emerging from advances in micro-sensor technology; generate data with high spatial and temporal resolution, complementing the limitations of fixed stations. Real-time data is typically accessible via online platforms.

Water Quality Measurement Technologies

Water quality measurement technologies encompass the methods and instruments used to determine the physical, chemical, and biological properties of water across a broad spectrum, from drinking water sources to lake and river ecosystems, agricultural irrigation systems, and industrial wastewater. These technologies are critically important for protecting water resources, sustaining ecosystem health, ensuring suitability for human consumption, and achieving compliance with legal environmental standards.

Key Parameters Measured

The main parameters considered in water quality assessments include:

• Physical parameters: Temperature, turbidity, and suspended solid concentration.
• Chemical parameters: pH, conductivity, oxidation-reduction potential (ORP), dissolved oxygen, nutrient salts (e.g., nitrate, phosphate), heavy metals (lead, mercury, cadmium), and organic pollutants.
• Biological parameters: Chlorophyll-a, cyanobacteria, bacteriological indicators (e.g., coliform bacteria), and other biological indicators that directly reflect ecosystem health.
• Pollution indicators: Chemical oxygen demand (COD) and biochemical oxygen demand (BOD); critical parameters for assessing organic matter pollution.

Measurement Instruments and Methods

Both portable instruments and continuous monitoring systems are used to measure water quality parameters.

• Physicochemical analyses:
• • pH meters: Determine the acidity or alkalinity of water using an electrode-based measurement principle.
  • Conductivity meters: Provide information about the concentration of dissolved ions.
  • Dissolved oxygen sensors: Measure oxygen levels in water using electrochemical or optical principles.
  • Spectrophotometers: Determine concentrations of nutrient salts, organic compounds, and metal ions by measuring light transmission or absorption at specific wavelengths.
• Automated water sample analysis systems: Used in large water bodies or industrial facilities; consist of automatic samplers, continuously operating sensors, and multi-parameter analyzers. Enable monitoring of instantaneous water quality changes and facilitate the generation of long-term data series.
• Biosensors: Increasingly used for rapid and sensitive detection of specific biological pollutants or toxins. Enzyme-based or DNA-based sensors are gaining importance in early detection of microbial contamination.
• Remote sensing and satellite-based methods: Used especially in large lake and river systems to determine chlorophyll-a concentrations, algal blooms, and turbidity levels.

Applications and Systems

Water quality monitoring technologies serve diverse scales and purposes.

• Drinking water treatment plants: Conduct multi-parameter measurements to ensure source water safety and monitor the effectiveness of treatment processes.
• Wastewater treatment systems: Control whether effluent meets discharge standards.
• Agricultural irrigation water monitoring: Evaluate the suitability of irrigation water with respect to salinity, nutrient content, and chemical contamination.
• Fish farms and aquaculture: Continuous monitoring of dissolved oxygen, temperature, and pH is essential for efficient and healthy production.
• Hydroelectric power plants: Monitor water quality in reservoirs to assess ecological impacts.
• Ballast water management: Under international maritime regulations, biological and chemical parameters of ballast water carried by ships are controlled.

Modern Monitoring Systems

Advanced water quality tracking systems collect and record measurement data in real time and transmit it via wireless communication technologies (Wi-Fi, GPRS, LTE) to cloud-based platforms. Users can access this data through online dashboards, mobile applications, or web interfaces. Additionally, automated alert systems (SMS, email, voice call) activate when predefined threshold values are exceeded, enabling rapid intervention. These systems also have long-term data storage capacity, facilitating the analysis of environmental trends over extended periods.

Data Management and Integration

One of the core components of air and water quality measurement systems is the processing, storage, integration, and presentation of collected data. Equipping measurement technologies with accurate sensors alone is insufficient; the data obtained must also be reliably processed, archived over the long term, and analyzed. Therefore, data management lies at the heart of environmental monitoring infrastructure.

Data Processing and Storage

Modern monitoring devices use embedded microprocessors and application-specific integrated circuits (ASICs) to process raw measurement data in real time. These systems can automatically perform preprocessing tasks such as noise filtering, calibration corrections, data compression, and error checking. Measured data is stored in the devices’ internal memory, SD cards, or portable storage. While some sensors can retain only a few hundred data points, advanced devices can store tens of thousands of measurements. In industrial-scale systems, uninterrupted data logging can extend up to 10–15 years.

Data Transmission and Communication Protocols

Different interfaces and communication protocols are used to deliver collected data to users.

• Local access methods: Data can be transferred to computers or recording systems via USB, RS232, or RS485 connections.
• Industrial communication protocols: Standards such as Modbus, Profibus, or OPC-UA enable sensors to operate compatibly with industrial control systems (particularly SCADA – Supervisory Control and Data Acquisition). This allows real-time monitoring of measurement data within infrastructure such as energy facilities, wastewater treatment units, or environmental control centers.
• Wireless communication: Technologies such as Wi-Fi, GPRS, LTE, and LoRaWAN enable devices to maintain uninterrupted communication in remote areas. These methods are widely used for water quality stations in mountainous regions or densely distributed air sensors in urban areas.

Cloud-Based Platforms and Data Integration

Modern environmental monitoring systems enable the transfer of collected data to cloud-based platforms. This approach allows real-time access and analysis of data by diverse user groups via the internet. Cloud-based integration also facilitates the centralization of data from monitoring stations across different regions and enables spatiotemporal comparisons.

Data Presentation and Decision Support Systems

Air quality data is typically converted into standardized indicators such as the Air Quality Index (AQI) to make it more understandable for the public and decision-makers. These indices express pollutant levels in simple, accessible formats using color coding and graphical visuals. Similarly, water quality assessments use classification tables and visual dashboards based on national and international standards. These systems serve not only as tools for environmental monitoring but also as decision support instruments for policy development, emergency management, public health warning systems, and industrial inspections.