The COVID-19 pandemic, with over 700 million cases globally, highlighted our unpreparedness for airborne biological threats. Effective air sampling has emerged as a critical tool for monitoring bioaerosols, ensuring we are better equipped to respond to future outbreaks.
What is air sampling?
Air sampling involves collecting airborne microbes (bioaerosols) to analyse microbial air composition, serving as a method for environmental surveillance.
Techniques like polymerase chain reaction (PCR) and metagenomic sequencing help identify microbes responsible for airborne infections, facilitating risk assessments in industrial settings and infection differentiation in medical diagnoses.
Air sampling involves collecting airborne microbes (bioaerosols) to analyse microbial air composition, serving as a method for environmental surveillance
The Nucleic Acid Observatory is currently investigating air sampling for pathogen early warning and improved disease surveillance.
Meanwhile, in Norwich, air sampling is currently being employed to study and monitor bioaerosols that might threaten crops. This method would allow farmers to adopt targeted chemical applications, reducing costs and enhancing crop efficiency while reducing the environmental impact of unnecessary pesticide usage.
Traditional air-sampling methods
While the Environment Agency sets standards for air sampling, it primarily addresses the process rather than specific area limits. However, following COVID-19, effective air sampling methods have become essential for indoor virus detection, contributing to better infection control strategies and enhancing occupational health monitoring.
The two most common air-sampling methods are impactors and settle plates. Impactors use inertial forces to accelerate air toward an agar plate.
Settle plates passively collect bioaerosols by having an agar plate open, allowing particles to settle over time
Larger particles impact the agar, while smaller particles follow the air streamline, allowing for size differentiation. However, agar can quickly dry out, leading to desiccation and reduced microbial growth. This method struggles to collect small bioaerosols, such as viruses smaller than one micron.
Settle plates passively collect bioaerosols by having an agar plate open, allowing particles to settle over time. This method is inexpensive and simple, allowing for sampling in multiple areas while other work continues. However, settle plates yield non-quantitative results since the volume of air sampled cannot be calculated.
Like impactors, they may disproportionately represent larger particles with a rapid settling rate, while small particles often resist settling due to air turbulence, requiring longer exposure and risking desiccation.
Dry filter elution
Dry filter elution, exemplified by the AirPrep Cub Sampler from Innovaprep, is an advanced air sampling method. It directs air through a dry electret filter, capturing particles using electrostatic and mechanical forces from positively and negatively charged fibres.
The filter is then subject to a wet foam elution process, where a carbonated fluid expands to form microbubbles, agitating and dislodging particles. The microbubbles then collapse back into a liquid state, ready for PCR and metagenomic sequencing analysis.
This method offers significant advantages: the AirPrep can sample up to 200 litres of air per minute (LPM), collecting clinically relevant levels of bioaerosol coronavirus in just 30 minutes, unlike traditional methods that require multiday incubation. The charged electret filter traps smaller particles than a mechanical filter, enabling detection of particles at the nanometre scale such as small viruses and fungal spores.
Dry filter elution, exemplified by the AirPrep Cub Sampler from Innovaprep, is an advanced air sampling method
For effective air sampling, consider your study's needs. Traditional methods are cost- effective but may miss smaller bioaerosols. Advanced methods instead capture a wider range of particles and offer faster, more accurate results.
Investing in advanced technologies enhances bioaerosol detection, improving public health and safety. For
high-risk environments or where precise monitoring is crucial, upgrading to elution filters ensures reliable data, enabling informed decisions in laboratory, healthcare, and agricultural settings.
Air sampling has become a crucial tool for environmental surveillance and public health, particularly in the wake of the COVID-19 pandemic. Embracing advanced air sampling techniques will enable us to monitor airborne pathogens, protect public health and support agricultural productivity.