Air quality & workforce health

Absenteeism had a cause that rarely makes it onto the HR dashboard.

It's in the air — specifically, the ventilation rates, fine particulates, and microbial buildup inside the HVAC system already running above your ceiling. The research linking building air to sick leave is more solid, and older, than most people realize.

A cost you're probably already tracking

Absence is one of the most closely watched numbers in workforce cost management. What's tracked less closely is how much of it originates in the building itself, rather than flu season or morale.

$225.8B

Estimated annual cost of employee absenteeism to U.S. employers, around $1,685 per employee

Compiled workforce-cost analysis, 2025

£429–£702

Per-employee annual absence cost in the UK, depending on company size

Verve Healthcare, 2025 employer analysis

Most absenteeism strategies focus on policy, scheduling, and morale. Building air quality is rarely on that list — despite a research base going back over two decades that treats it as a measurable, quantifiable factor.

The science

What the evidence says about ventilation and health

The relationship between ventilation and health isn't based on a single study or isolated finding. It's supported by decades of research across offices, schools, military housing, and childcare centres. Although these studies examined different environments using different methods, they consistently reached the same conclusion: better ventilation creates healthier indoor spaces and helps reduce illness.

Better ventilation means fewer sick building symptoms. A major review by Lawrence Berkeley National Laboratory found that most studies reported significantly more complaints—such as headaches, fatigue, difficulty concentrating, and irritated eyes or throats—in buildings with lower ventilation rates. Similarly, the U.S. Environmental Protection Agency found that office spaces with higher ventilation had 20–30% fewer people reporting these symptoms than spaces with poorer airflow.

It also reduces the spread of respiratory illness. Studies in military barracks, prisons, and nursing homes consistently found much higher rates of respiratory illness where ventilation was poor. The reason is simple: when someone coughs or sneezes, viruses and bacteria can remain suspended in the air for longer and build up to higher concentrations if there isn't enough fresh air entering the space. Better ventilation helps dilute and remove these airborne particles, reducing the chances of others becoming ill.

Ventilation and actual sick leave. Studies consistently show that better ventilation reduces illness-related absences. Doubling outdoor air supply cut short-term sick leave by 35% in offices, while higher ventilation rates also reduced absences in schools and daycare centres.

Fine particulates (PM2.5). Research shows that higher PM2.5 levels increase sick leave. A Stockholm study found an 8.5% rise in the odds of a sick-leave episode for every 10 µg/m³ increase in PM2.5, while a nationwide French study linked higher PM2.5 exposure to increased worker absenteeism.

Dampness, mould, and respiratory health. The World Health Organization identifies dampness and mould as strong indicators of increased risk for respiratory infections, respiratory symptoms, and worsened asthma.

Where it starts

It usually starts on the coil, not in the room

The air people breathe indoors has already passed through the HVAC system, so what happens inside it affects everything downstream.

Cooling coils are warm, dark, and constantly damp from condensation, making them an ideal environment for bacteria and fungi. Research has found established microbial communities on filters, coils, fans, and air outlets. Once biofilms form on coils, they reduce heat-transfer efficiency and can release microbes back into occupied spaces. Studies also show that coils protected by lower-efficiency filters accumulate significantly more bacteria and fungi than those behind finer filtration.

The impact isn't just on air quality. Fouled coils can increase cooling energy use by up to 30%, heating energy by up to 15%, and fan energy by up to 25%. While routine cleaning helps, it doesn't fully restore performance, and coils begin fouling again almost immediately after they're cleaned.

the retrofit

HiboScreen

Clinical-Grade Air. Lower Energy Costs. Simple Retrofit

A retrofittable electrostatic screen for HVAC systems. Using Airborne Particle Engineering™, it charges fine airborne particles so they cluster together, letting the standard G4 and F7 filters already installed capture them, without replacing the system or adding meaningful pressure drop.

Fits upstream of the existing G4/F7 filter inside the air handling unit — plug-and-play, no mechanical modification, no downtime.

Generates a controlled, low-density electrostatic field (4–6 kV) that polarises and lightly charges fine airborne particles as they pass through, causing them to cluster into larger groups.

The same field neutralises airborne bacteria, viruses, and mould spores directly.

Once clustered, particles are captured by the standard filter already in the system — one that would have missed them individually.

Coils stay clean continuously, instead of being cleaned periodically after fouling has already degraded performance.

Energy savings per air handling unit, vs. an annual coil-cleaning schedule

17%

5.8t

CO2 reduction per AHU per year

Reduction in fine particulate matter

96.4%

Single-pass filtration equivalent (ISO ePM1 85%) from the existing filter

F9/MERV15

Independently tested pathogen and mould neutralisation, by organism:

reduction

Organism

H1N1 virus

99.92%

MTB Bacteria

99.57%

MS2 (COVID surrogate)

98.31%

CA (mould surrogate)

90.5%

Pressure drop stays low and negligible: the screen works electrostatically, not by tightening the mesh, so it doesn't choke airflow. Payback lands under 12 months in every comparison scenario in the underlying whitepaper, including the most conservative one (semi-annual coil cleaning).

What it is

A retrofit upgrade to the HVAC infrastructure already installed.

What it's not

Not a standalone air purifier, and not a filter replacement — it adds to what's there, it doesn't swap it out.

Where HiboScreen fits in the evidence

What the research above establishes is a chain: ventilation effectiveness, fine particulate levels, and microbial load on HVAC coils are all measurably connected to sick building symptoms, respiratory illness, and documented sick-leave rates, across dozens of independent studies over more than 20 years.

HiboScreen is designed to improve one of the key drivers of indoor air quality: HVAC filtration performance. By reducing airborne particulates and preventing coil fouling, it addresses an important part of the evidence-based pathway linking cleaner air to healthier buildings.

The research supports a clear chain linking HVAC performance, indoor air quality and employee health. HiboScreen is engineered to improve the air quality part of that evidence-based pathway.

the next step

See it on your own system before you decide anything

A Demonstration of Technology is simple to implement. We identify a suitable AHU, install a HiboScreen, and monitor its performance. You'll receive pre- and post-installation data, along with access to a dashboard that clearly demonstrates the impact of the technology.

SOURCES

TeamSense, "20 Statistics Centered Around Employee Absenteeism," 2025 — U.S. absenteeism cost estimate.
Verve Healthcare, "The Cost of Absenteeism to UK Employers," 2025 analysis.
Fisk, W.J., Mirer, A.G., Mendell, M.J., "Quantitative relationship of sick building syndrome symptoms with ventilation rates," Indoor Air, 2009; Seppänen, O.A., Fisk, W.J., Mendell, M.J., Indoor Air, 1999 — via Lawrence Berkeley National Laboratory's Indoor Air Quality Scientific Findings Resource Bank.
Mendell, M.J., et al., "Outdoor air ventilation and work-related symptoms in U.S. office buildings — results from the BASE study," LBNL, 2005.
Seppänen et al., 1999, summarising Brundage et al. (JAMA, 1988), Drinka et al. (J Am Geriatr Soc, 1996), and Hoge et al. (NEJM, 1994) — ventilation and respiratory illness in institutional settings.
Milton, D.K., Glencross, P.M., Walters, M.D., "Risk of sick leave associated with outdoor air supply rate, humidification, and occupant complaints," Indoor Air, 2000.
Mendell, M.J., et al., "Association of classroom ventilation with reduced illness absence: a prospective study in California elementary schools," Indoor Air, 2013.
Kolarik, B., et al., "Ventilation in day care centers and sick leave among nursery children," Indoor Air, 2016.
Stockholm case-crossover study on short-term PM2.5 exposure and sick leave episodes, Environment International / ScienceDirect, 2023.
Linked employer-employee data study, France 2009–2015, on monthly PM2.5 exposure and worker absenteeism.
World Health Organization, "WHO Guidelines for Indoor Air Quality: Dampness and Mould," 2009.
Studies of bacterial and fungal communities on HVAC cooling coils and the influence of upstream filter grade (MERV rating) on microbial loading — PMC / peer-reviewed microbiology literature.
HiboScreen whitepaper, Western Cape laboratory testing — energy, particulate, and pathogen/mould figures as locked in the HiboCare Positioning Playbook v1.
US Department of Energy — coil fouling energy penalty figures.

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