In the post-pandemic world, indoor air quality (IAQ) is no longer a silent factor in workplace well-being; it’s front and centre in discussions about employee health, cognitive function, and even infection control. As businesses adapt to evolving occupational health standards and employee expectations, the demand for healthier indoor environments has surged.

A recent case study was conducted at the CAREL5 Knowledge Center, one of the buildings at CAREL Industries S.p.A. Headquarters in Padua, Italy. It provides insightful data on how comprehensive IAQ monitoring can enhance workplace performance and reduce health risks. By evaluating temperature, humidity, CO₂ levels, and particulate matter (PM), the study aligns air quality parameters with international guidelines and explores airborne infection risks using advanced modelling tools.
Here below is what the study revealed and why it matters for any organisation aiming to optimise both human health and workplace performance.

The air we breathe at work: why it matters

Poor IAQ isn’t just a comfort issue; it’s also a productivity killer. Studies have consistently linked high levels of CO₂ and airborne pollutants to symptoms such as headaches, fatigue, and reduced cognitive function. Conversely, optimised IAQ improves concentration, creativity, and overall job satisfaction.

Methodology: measuring what matters

The indoor environmental quality (IEQ) at CAREL5 was measured based on data sampled in January and February 2025, and focused on three key areas in the building: the office, the canteen, and the kitchen, representing diverse activity levels and occupancy rates.

The assessment utilised a supervisory system that maps and trends IAQ in both real time and based on logged data. The system acquires and displays environmental metrics across different rooms, allowing detailed understanding of air quality fluctuations and the factors that influence them.

Indoor air quality monitoring, trend display

The key parameters measured included:

• CO₂ concentration (a proxy for ventilation efficiency)
• Relative humidity (RH) (linked to respiratory health and comfort)
• Temperature (impacting thermal comfort and performance)
• PM10 concentrations (airborne particles potentially harmful to respiratory health)

All measurements were compared against the standards set by ASHRAE (American Society of Heating, Refrigeration and Air-Conditioning Engineers) and WHO (World Health Organisation), which recommend:

• CO₂ levels below 1000 ppm
• Relative humidity between 30% - 60%
• Temperature between 19–27°C
• PM10 concentration below 45 µg/m³ (WHO 24-hour mean)

Key findings: how does the building measure up?

1. CO₂ concentrations

The median value, followed by the 5th and 95th percentiles of the monitored indoor areas in the CAREL5 building, is:

• Kitchen: 430 ppm (411- 511) ppm
• Office: 779 ppm (691 – 863) ppm
• Canteen: 975 ppm (833 – 1102) ppm

All three environments remained under the 1000 ppm threshold recommended by ASHRAE. However, the canteen was close to the upper limit, suggesting the need for dynamic ventilation adjustments during peak usage, which, fortunately, the system is designed to manage automatically in response to CO₂ levels.

2. Temperature

All areas averaged between 21°C and 22°C, staying well within the recommended thermal comfort range. This helps prevent fatigue and supports consistent productivity throughout the day.

3. Humidity

Relative humidity levels across all spaces ranged from 46–49%, representing optimal indoor comfort and minimising the risk of respiratory irritation or pathogen viability.

4. PM10 levels

• Kitchen: 10.5 µg/m³
• Office: 9 µg/m³
• Canteen: 3 µg/m³

These values are significantly below the WHO’s 24-hour limit of 45 µg/m³, highlighting the effectiveness of the filtration and ventilation systems in place.

Infection risk: the ARIA tool

With health concerns shifting post-COVID-19, another aspect of the analysis focused on the airborne transmission risk, specifically for SARS-CoV-2, using the WHO-endorsed Airborne Risk Indoor Assessment (ARIA) tool. This model simulates infection risk based on variables such as room volume, occupancy, ventilation rates, exposure time, and activity type (e.g., breathing vs. speaking).

To have insight into the worst-case scenario, short-range interaction was considered in all situations. Activities that are impossible, such as an infected person speaking the entire time (8 hours & 2 hours) in the office and canteen respectively were also considered for prediction of the worst-case scenarios. 

Office risk scenarios (20 occupants, 8-hour exposure)

• 100% breathing : 8.1% risk, 0.12 expected new cases
• 50% breathing and 50% speaking: 8.9% risk, 0.63 expected new cases
• 100% speaking: 9.5% risk, 0.94 expected new cases

Canteen risk scenarios (216 occupants, 2-hour exposure)

• 100% breathing: 3.6% risk, 0.11 expected new cases
• 50% breathing and 50% speaking: 3.7% risk, 0.96 expected new cases
• 100% speaking: 3.9% risk, 1.7 expected new cases

These projections underscore the importance of adequate ventilation in infection control. Notably, the canteen, despite the higher occupancy, showed relatively lower infection risk thanks to its larger volume and higher airflow of 1800 m³/hr, as well as the shorter time people spend in the canteen.  In addition, the fresh air damper is automatically adjusted based on the CO₂ level.

Predictive insights: anticipating CO₂ buildup

The study also included a comparison between the prediction of CO₂ concentration trends from ARIA and the actual data analysed by the system used in CAREL 5. These projections help facility managers anticipate when and where ventilation needs to be ramped up, proactively maintaining air quality before thresholds are exceeded. 

ARIA predictive CO₂ concentration profile in the office

ARIA predictive CO₂ concentration profile in the canteen

There is a slight difference in the observed trend, which is acceptable and stems from expected real conditions. In the ARIA model, office occupancy between 12:00 and 14:00 is assumed to drop to zero, as this period is designated as the lunch break. However, in practice, employees do not all take lunch at the same time; some may leave at around 12:30, others closer to 13:00. This staggered behaviour contributes to the observed variation. Furthermore, the CO₂ concentration profile in the canteen predicted by ARIA differs from the actual data due to automatic activation of the fresh air damper, which increases ventilation as CO₂ levels rise. In actual fact, the canteen is rarely fully occupied at any one time, which also contributes to the discrepancy between the modelled and measured values. 

This forward-looking approach is especially valuable in large-scale operations where occupancy and activity levels fluctuate throughout the day.

Indoor air is the invisible backbone of any workplace. While lighting, furniture, and open spaces are often prioritised, the air we breathe has a more profound and often overlooked impact on our daily functioning.

This case study illustrates how robust indoor air quality (IAQ) monitoring, when aligned with international guidelines, can deliver significant benefits across workplace environments. It ensures compliance with ASHRAE and WHO standards while protecting the health and well-being of occupants by minimising exposure to pollutants and airborne infectious agents. By optimising comfort and cognitive performance, it directly contributes to increased productivity. Moreover, the integration of actual data and predictive modelling supports more informed, data-driven decision-making. This proactive approach also enhances organisational resilience against respiratory disease outbreaks. By leveraging digital tools and the WHO’s ARIA model, companies can transition from reactive responses to proactive environmental management strategies.

References:

Felgueiras, F., Mourão, Z., Moreira, A., & Gabriel, M. F. (2023). Indoor environmental quality in offices and risk of health and productivity complaints at work: A literature review. Journal of Hazardous Materials Advances, 10, 100314. https://doi.org/10.1016/j.hazadv.2023.100314

WHO ARIA-Tool https://partnersplatform.who.int/tools/aria/

ASHRAE Position Document on Indoor Carbon Dioxide https://www.ashrae.org

HUMIDIFIERS https://www.ashrae.org/file%20library/technical%20resources/covid-19/i-p_s16_ch22humidifiers.pdf

WHO Guidelines on Indoor Air quality and the role of Air quality monitors https://www.hibouair.com/blog/who-guidelines-on-indoor-air-quality-and-the-role-of-air-quality-monitors