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Continuous air quality monitoring for ...

Continuous air quality monitoring for harmful particulate matter and aerosols

Jul. 12, 2023

Air pollution is defined by the World Health Organization (WHO) as «contamination of the indoor or outdoor environment by any chemical, physical or biological agent that modifies the natural characteristics of the atmosphere» [1]. When air pollution levels are high, this can lead to respiratory problems, heart disease, and other illnesses (e.g., cancer). It can also cause acid rain, damage crops, reduce plant growth and productivity, and harm wildlife. Since 99% of the global population breathes air that exceeds WHO quality guideline limits [1,2], this is a widespread issue. Among the various air pollutants, particulate matter and aerosols are of particular concern. This blog article discusses these contributors to air pollution and highlights two instruments dedicated to continuously monitoring air quality parameters.

Brief introduction to particulate matter and aerosols\r\n

Particulate matter (PM) is generally defined as small solid particles suspended in a gas, while aerosols are finer liquid droplets or solid particles that remain suspended in gases for significant periods of time. Both of these can negatively affect human health, especially when their diameters are less than 2.5 µm (PM_2.5,Figure 1). Aerosols and PM can be created by natural occurrences such as volcanic eruptions, as well as anthropogenic activities such as industrial operations and transportation. Therefore, it is important to analyze the chemical composition of these pollutants not only to determine the long-term effects after exposure, but also to identify their sources in order to take steps to reduce emissions.

Brief introduction to particulate matter and aerosols

Particulate matter (PM) is generally defined as small solid particles suspended in a gas, while aerosols are finer liquid droplets or solid particles that remain suspended in gases for significant periods of time. Both of these can negatively affect human health, especially when their diameters are less than 2.5 µm (PM_2.5, Figure 1). Aerosols and PM can be created by natural occurrences such as volcanic eruptions, as well as anthropogenic activities such as industrial operations and transportation. Therefore, it is important to analyze the chemical composition of these pollutants not only to determine the long-term effects after exposure, but also to identify their sources in order to take steps to reduce emissions.

Figure 1.Particulate matter size comparison. Adapted from [3].

Once in the air, these miniscule particles can be transported across long distances, causing complications far from their source. The smaller the particles’ size, the deeper they can infiltrate the respiratory system. Several studies have linked PM to health problems (e.g., respiratory issues) and environmental issues (e.g., visibility impairment) [4–6]. While coarser dust particles (PM₁₀) are mostly retained by nasal hair, fine particles (PM_2.5) can penetrate deep into the lungs and cause irritation. Aerosols, on the other hand, are even smaller than PM particles and can therefore stay aloft in the atmosphere for extended periods.\r\n

To gain a better insight into the effects of air pollution on our health and the environment, there is a need for accurate measurements that determine the quantity and chemical composition of suspended particles at a high temporal resolution. However, thecollection of representative samplesand the associatedanalysisare themost challenging partsof air monitoring.

To gain a better insight into the effects of air pollution on our health and the environment, there is a need for accurate measurements that determine the quantity and chemical composition of suspended particles at a high temporal resolution. However, the collection of representative samples and the associated analysis are the most challenging parts of air monitoring.