Sensors and Analytical Technologies for Air Quality: Particulate Matters and Bioaerosols

Particulate matters (PMs), e. g. dusts, fibres, smokes, fumes, mists, liquid droplets and airborne respirable solid or liquid particles, are the major sources of air pollution concerning outdoor and indoor air quality. Among various PMs, bioaerosols are airborne particles that are either living organisms (bacteria, viruses, and fungi) or originate from living organisms (endotoxin, allergen, etc). PMs and/or bioaerosols have adverse health effects of infection, allergy, and irritation. Proper management and source identification of PMs and bioaerosols will reduce their negative health impact. In this review, we will discuss the analytical technologies and sensors for PMs and bioaerosols. We will first introduce four types of PM analysers, namely, filter-based gravimetric method (GMM), optical method, beta-ray absorption method (BAM), and tapered element oscillating microbalance (TEOM). We will provide examples of how commercial PM analyzers of different principles have been compared and calibrated for specific applications under different climate conditions of specific geographic locations. For bioaerosols, having more complex biological and biochemical identity, we will start from air sampling techniques, followed by a discussion of various detection methods (plate culture, molecular methods, immunoassays and biosensors) in association with compatible sampling technologies. Using Influenza A (H1 N1) virus and SARS-CoV-2 (COVID-19) virus as examples, we have highlighted air sampling and detection challenges for viral aerosols relative to bacterial and fungal aerosols. Finally, we provide a perspective for future trends according to the limitation of current commercial products and the key challenges in this field.