Author: Sotirios Papathanasiou

WELL Building Institute Air Advisor. Indoor Air Quality is the value that reassures the well-being of occupants. #AirPollution #AirQuality #ClimateChange

The Unseen Air Inside Classrooms

Sotirios Papathanasiou1 Comment

In the modern classroom, the focus is often on technology, curriculum, and engagement. However, a critical element that directly impacts student health and learning often goes overlooked: the air they breathe. In many schools, especially older buildings, ventilation systems are inadequate or non-existent. This can lead to a buildup of pollutants and, most critically, an increased risk of airborne infections.

The importance of good air quality cannot be overstated. A well-ventilated space keeps the concentration of airborne particles at bay, including viruses and bacteria. When traditional ventilation falls short, supplementary solutions become essential. This is where air purifiers, both commercial and do-it-yourself (DIY), offer a viable and often more affordable solution.

Read More »

AirDummies: A Breath of Fresh Air for Indoor Environment Simulation

Sotirios Papathanasiou3 Comments

AirDummies emerges as a highly intuitive and powerful Computational Fluid Dynamics (CFD) software, purpose-built to demystify the complex world of indoor air dynamics. Designed with a clear focus on accessibility, it caters to a broad spectrum of users, offering invaluable insights into air patterns within diverse indoor environments, including school classrooms, offices, and domestic settings. Its ability to simulate everything from CO2 concentrations, particle contaminants, and temperature gradients to air velocity makes it an indispensable tool for optimizing comfort, health, and energy efficiency.

AirDummies is built upon the OpenFOAM open-source library. This foundational relationship means AirDummies leverages OpenFOAM’s extensive capabilities for simulating fluid flow, heat transfer, and related phenomena. By utilizing OpenFOAM, AirDummies benefits from a robust, well-validated, and continuously developed CFD engine, providing users with a powerful and flexible platform for their simulation needs.

Read More »

Latvia’s Model for Healthy Learning: The MESH Air Quality Project

Sotirios PapathanasiouLeave a comment

Latvia has successfully deployed 14,000 CO2 monitors in hundreds of schools, ensuring safer and healthier learning environments for students and teachers. This nationwide initiative, launched by the Ministry of Education and Science of Latvia and implemented by the technology company MESH, addresses concerns about elevated CO₂ levels, which can contribute to the transmission of pathogens and affect concentration. Such successful projects should serve as a blueprint for others aiming to improve indoor air quality and efficiency in public buildings. The data collected from these monitors is freely accessible to the public via the website https://co2.mesh.lv/home/dashboard, providing transparency and peace of mind for parents.

The project, which involved an initial investment of €3.58M, translates to an approximate cost of 12 euros per student. This cost-effective solution was designed to significantly improve cognitive abilities and health, as well as air quality, for 300,000 children across Latvian schools. Even without adding heating control, facility managers were able to optimize energy use by simply analyzing temperature trends available online – leading to smarter manual adjustments and early savings in several municipalities. Following the project, some municipalities further developed the system by integrating automatic regulation of heat nodes, and in one case, the investment was fully recouped within a single heating season.

Read More »

Unveiling Urban Health: The ISGlobal Ranking of Cities and its Healthy Urban Design Index (HUDI)

Sotirios PapathanasiouLeave a comment

In an era where urban populations continue to swell, understanding the intricate relationship between city design and public health is fundamental. The Barcelona Institute for Global Health (ISGlobal) has emerged as a leading voice in this field with its “ISGlobal Ranking of Cities” and the innovative “Healthy Urban Design Index (HUDI).” This comprehensive tool sheds light on the health impacts of urban exposures like air pollution, noise pollution, and access to green spaces across nearly 1,000 European cities.

The ISGlobal Ranking of Cities is more than just a list; it’s a dynamic project aimed at quantifying the health burdens attributable to urban and transport planning. It evaluates various environmental exposures and their associated mortality, presenting cities from the highest to lowest mortality due to these factors. You can explore the tool directly on the ISGlobal Ranking of Cities website.

At the heart of this initiative is the Healthy Urban Design Index (HUDI). The HUDI is a composite score that meticulously assesses the extent to which the configuration of European cities supports the health and well-being of their inhabitants. It examines 13 key indicators across four domains: urban design, sustainable transport, environmental quality, and green space accessibility. These indicators include factors such as urban compactness, housing density, walking and cycling infrastructure, public transport availability, air pollution levels, capacity to mitigate heat, and accessibility of green spaces. Each city receives a score between 0 and 10 for each indicator, culminating in an overall HUDI score.

Read More »

Introducing FantaMix: An Innovative DIY Ventilation Solution

Sotirios Papathanasiou1 Comment

At See The Air, I am always excited to share innovative approaches to improving indoor air quality. Today, I am highlighting some fantastic articles by Nathalie Roussy that delve into the world of DIY ventilation with her in-depth work on the FantaMix.

FantaMix Review: A Look at Performance and Impact

Nathalie’s comprehensive review, titled “FantaMix Review,” was originally published on Medium. You can read her full article here.

The FantaMix is a compact, open-source ventilation system designed for home construction at a low cost. Nathalie, who is the designer and tester of the FantaMix, explains how this hybrid device filters a mix of fresh outdoor air and stale indoor air through an H11 HEPA filter, all while recovering lost heat. It functions as both a source of fresh air and an indoor air purifier.

Her article covers the origins of the FantaMix, how it works, and the results of various field tests, including airflow rate, noise level, heat recovery, and power consumption. She also provides a comparison with similar devices and a visual analysis of CO₂ levels to demonstrate its impact on air quality. Nathalie emphasizes that the FantaMix is a DIY project, offering an accessible solution for enhancing indoor air quality, particularly for renters or those with budget constraints, and is especially beneficial during events like wildfires.

Building the FantaMix: Your Step-by-Step Guide

For those inspired to build their own FantaMix, Nathalie has also published a detailed DIY guide titled “Building the FantaMix: Fresh Filtered Air at Home — No Exhaust, Under $200,” also available on Medium. Find the complete guide here.

This step-by-step open-source guide outlines how to create this affordable and effective home ventilation system. The FantaMix aims to provide fresh, HEPA-filtered outdoor air with partial heat recovery, costing under $200 and requiring no major construction or exhaust system. The project is 100% open source, promoting accessible knowledge over opaque products. The article covers the detailed construction process, including building the base, assembling the top section, preparing the outdoor air intake panel, and installing components like fans, insulation, and wiring. It also includes a detailed cost breakdown, a list of essential and optional tools, and crucial safety precautions, especially when working with materials like heated foam. Maintenance tips for filter replacement and fan cleaning are also provided.

I am particularly proud to note that Nathalie’s work on the FantaMix was inspired by our very own article, “DIY Ventilation Solution for Renters.” It’s wonderful to see how shared knowledge and innovation can lead to such practical and impactful solutions for healthier living spaces.

We highly recommend reading Nathalie’s articles to learn more about the FantaMix and consider it as a potential DIY project for your own home!

A Compromised Approach to Indoor Air Quality Assessment

Sotirios Papathanasiou2 Comments

Professionals in the field of indoor air quality sometimes compromise the accuracy of their assessments by opting for short-term sampling periods. While quick measurements can provide preliminary insights, they may not accurately reflect the dynamic nature of indoor air quality. Factors such as occupancy patterns, ventilation systems, and external influences can significantly impact pollutant concentrations over time. By relying on brief sampling periods, professionals risk drawing incorrect conclusions about long-term exposure risks and the effectiveness of mitigation strategies. To obtain a comprehensive understanding of indoor air quality, it is essential to employ continuous monitoring techniques or extended sampling periods that capture the full range of variations in pollutant levels.

Common Misconceptions about Air Quality Monitoring

A prevalent misconception in the field is the practice of taking short-term air samples, often lasting 10 minutes or an hour, to assess indoor air quality. While this approach might provide a snapshot of conditions at a specific moment, it fails to capture the full picture of air quality fluctuations over time. Such limited data can lead to inaccurate conclusions and potentially miss critical issues that may arise during occupied or unoccupied periods or under different operational conditions.

Comprehensive Air Quality Monitoring: A Holistic Approach

To effectively evaluate indoor air quality, a more comprehensive approach is required. Continuous monitoring systems equipped with sensors capable of measuring various pollutants, including carbon dioxide, volatile organic compounds (VOCs), particulate matter, and temperature and humidity, offer a more accurate and insightful assessment.

These systems can collect data at regular intervals, providing real-time insights into air quality trends and enabling timely interventions to address any issues that may arise.

Specific Pollutants and Monitoring Techniques

Different pollutants require specific monitoring techniques:

  • Particulate Matter: Regulatory limits for PM2.5 are commonly specified for 24-hour or annual averages. Consequently, sampling protocols should be designed to capture these temporal scales. The World Health Organization (WHO) has established guideline limits of 5 μg/m³ for the annual mean and 15 μg/m³ for the 24-hour mean of PM2.5.
  • Radon: Radon limits are based on annual concentrations. To accurately assess the average annual radon level in a home, it’s crucial to strategically place radon measurement devices in areas where occupants spend the most time, such as bedrooms, living rooms, and basements. The measurement period should ideally be at least 91 days to ensure a reliable estimate of the average annual exposure. However, to ensure an accurate assessment of the average annual radon level in a home, Health Canada recommends conducting radon tests over a period of 3 to 12 months. This timeframe allows for a comprehensive evaluation of radon fluctuations throughout the year and provides a reliable estimate of long-term exposure.
  • Gases: In many cases a diffusion tube, which is a scientific instrument designed to passively measure the concentration of specific gases (VOCs, NO2, etc.) in the air, is commonly used to track average air pollution levels over periods ranging from days to approximately a month. It’s important to note that longer sampling times generally improve the detection limits for low-concentration analytes, but they can also increase the risk of breakthrough, where analytes exceed the adsorbent capacity of the tube. Therefore, the optimal sampling time should be determined based on the specific analytical requirements and the characteristics of the sampling site. Additionally, continuous sensors, such as electrochemical, metal oxide, and UV absorption sensors, are employed to measure indoor gas concentrations. To ensure appropriate assessment against regulatory standards, the sampling duration should align with the specific timeframes established by these standards. For example, WHO has set a 24-hour limit of 25 μg/m³ for nitrogen dioxide (NO₂) and an 8-hour limit of 100 μg/m³ for ozone (O₃).
  • Carbon dioxide (CO2): CO2 monitoring in indoor spaces is essential for maintaining optimal ventilation rates and occupant well-being. An absolute threshold of around 800 or 1000 ppm has been established as a guideline for safe CO2 levels. To accurately assess CO2 concentrations, measurements should be taken when the room is fully occupied. This is because CO2 levels are primarily influenced by human activity, and empty spaces will not provide meaningful data. By monitoring CO2 levels during periods of maximum occupancy, we can ensure that the established threshold is not exceeded, reducing the risk of negative health impacts associated with poor indoor air quality. In certain cases, activities like cooking or burning candles can also contribute to elevated CO2 levels, necessitating additional monitoring considerations.

Air quality within buildings is not static; it fluctuates throughout the day due to various factors such as occupancy, activities, materials used, and environmental indoor and outdoor conditions like temperature, humidity, and air pressure. By understanding the dynamic nature of indoor air quality and employing appropriate monitoring techniques, building occupants can enjoy healthier and more productive environments.

Review: aranet Radiation ☢️

Sotirios Papathanasiou1 Comment

The aranet Radiation tackles a whole new frontier: personal radiation safety. This device promises to empower you by monitoring gamma (γ), beta (β), and x-ray levels, giving you insights into your environment’s radiation for years.

Pros:

  • Peace of Mind: Being aware of radiation levels can be a major stress reliever, especially in areas where radiation concerns might exist like near nuclear power plants.
  • Long-Term Tracking: With a two-year data tracking capability, the Aranet Radiation allows you to identify trends and build a picture of your overall radiation exposure.
  • Battery Life: Aranet devices are known for their impressive battery life, and the Radiation model is likely to follow suit.
Read More »

Understanding AHAM and CADR: Your Guide to Cleaner Indoor Air

Sotirios PapathanasiouLeave a comment


In today’s world, indoor air quality is more important than ever.  Dust, pollen, and even wildfire smoke can significantly impact our health and comfort. Air purifiers offer a solution, but navigating the world of product specifications can be confusing. Is product efficiency a sufficient way to rate them, or should we think about effectiveness? This article explains the role of the Association of Home Appliance Manufacturers (AHAM) and the importance of the Clean Air Delivery Rate (CADR) in choosing the right air purifier for your needs, plus an upcoming standard that wants to deliver even better indoor air solutions.  

Understanding CADR

The Clean Air Delivery Rate (CADR) is a crucial metric that indicates how quickly an air purifier can remove specific types of particles from a room.  It measures the volume of clean air delivered by the unit and is expressed in cubic meters per hour (CMH) or cubic feet per minute (CFM). AHAM tests air purifiers for three common pollutants; smoke, dust, and pollen. Note: CMH can be converted to CFM by dividing by 1.7.

Read More »

Benchmarking: The Ultimate Catalyst for Better Air Quality Through Global Standards

Sotirios PapathanasiouLeave a comment

This article first appeared on www.goaqs.org

Air quality is an invisible yet pervasive factor influencing our health, productivity, and overall well-being. While awareness of air pollution is growing, translating that awareness into actionable behavioral change remains a significant challenge. The key to unlocking this transformation lies in the power of benchmarking—a potent tool that, when coupled with global standards like the proposed Global Air Quality Standard (GO AQS), can empower individuals and communities to breathe cleaner air.

The Power of Comparison: Learning from Other Fields

The effectiveness of benchmarking as a driver for improvement is not a new concept; it has long been a cornerstone of success in diverse fields. Consider the world of athletics: elite athletes constantly benchmark their performance—speed, strength, endurance—against competitors in their category. This isn’t about shaming, but about identifying areas for improvement. A runner who sees their sprint times lagging behind others in their age group knows exactly where to focus their training. Similarly, in healthcare, patients track metrics like blood pressure or cholesterol against established healthy ranges or anonymized data from similar patient populations. This comparison provides a clear understanding of their health status, prompting necessary lifestyle changes or medical interventions.

A practical, personal example vividly illustrates this point: as an individual tracking my resting heart rate through an app that allows comparison against +56,000 users worldwide. Seeing a “superb” rating, indicating excellent heart aging, provides tangible positive reinforcement and validates my health efforts. Conversely, a less favorable comparison would flag a problematic area, encouraging focused action. This simple yet powerful mechanism of comparison fosters accountability and motivates behavioral adjustments.

Read More »

Key Insights from ASIC 2025 in Thailand: Bridging the Indoor-Outdoor Divide

Sotirios Papathanasiou1 Comment

The recent Air Sensors International Conference (ASIC) 2025, held in the vibrant backdrop of Thailand, offered a profound opportunity to delve into the evolving landscape of air quality monitoring. As an attendee, several key themes emerged that highlight both the progress made and the remaining challenges in our quest to understand the air we breathe.

The Indoor-Outdoor Air Quality Discrepancy

One striking observation from the conference was the apparent disparity in research emphasis between indoor and outdoor air quality monitoring. While outdoor environments have benefited immensely from the widespread adoption and scrutiny of low-cost air quality monitors, indoor spaces appear to lag in comparison. The primary reason for this imbalance lies in the availability of robust reference instrumentation. Governments worldwide have invested in publicly air quality stations equipped with reference-grade instruments, providing invaluable benchmarks for normalization and validating low-cost sensors in a variety of outdoor conditions. This has not only accelerated the development of accurate low-cost monitors but also fostered the creation of sophisticated correction algorithms.

Read More »