With one in three Australians now living with allergies and economic impacts estimated at $18.9 billion each year, indoor air quality is moving beyond a health discussion and into the realm of workplace performance. What makes the issue difficult to address is how quietly symptoms take hold.
“People often overlook indoor air during warmer months because the focus shifts to cooling rather than what that cooling process is doing to the indoor environment,” Litmus laboratory director and Integrated Bioscience and Built Environment Consortium (IBEC) vice president Claire Bird says. “Symptoms build gradually, so workers blame the commute or outdoor exposure when the trigger is often inside the building.”
Warmer weather changes how air behaves indoors. In environments without mechanical cooling, including construction sites and post remediation settings, heat stress becomes a serious concern. “Heat stress is a major contributor to adverse health outcomes such as cardiovascular events and strokes,” Bird explains. “When there are no thermal controls or suitable breaks, rest areas and fluids become essential for worker safety.”
In buildings with air-conditioning, reliance on mechanical systems increases as temperatures rise. “Warm weather is when we place the greatest demand on air-conditioning infrastructure, and that can compromise indoor environments if systems are not properly maintained,” she says.
Cooling humid air requires moisture removal, which creates its own risks. “Keeping relative humidity below 60 percent is critical for preventing mould and bacterial growth,” Bird notes. “The problem is that the moisture removed from the air often ends up inside the air-conditioning system itself.”
In split systems common in offices and schools, increased cooling demand leads to faster filter blockage. “Dust becomes a food source,” she says. “Moisture collects on coils and fins, which allows rapid colonisation by mould and harmful biofilms. These microbes are then dislodged when systems run and settle into carpets, soft furnishings and high level surfaces.”
When clean spaces still make people feel unwell
This explains why workplaces can look clean yet still make people sick. “Surface cleaning alone does not address what is happening in HVAC systems or in dust reservoirs throughout a building,” Bird says. “Research shows that when indoor humidity reaches around 80 percent, more harmful moulds and bacteria start growing in settled dust.”
Dry climates pose a different risk. “In places like South Australia or the ACT, excessive drying of air makes people more susceptible to airborne infections,” she explains. “Dry air damages the respiratory lining and allows infectious particles to stay airborne longer and travel further.”
Healthcare settings face heightened exposure. “Hospitals have higher densities of infectious people and greater risks to staff,” Bird says. “In warmer regions, increased biofilm growth in HVAC systems may also contribute to antimicrobial resistance, which makes infections harder to treat and increases pressure on healthcare workers.”
Jani-King CEO Ben Stoltz says his team faces these issues every day. “As allergy rates continue to climb, consistent and informed cleaning is no longer something businesses can overlook,” he says. “Trained cleaners know how allergens move, where they settle and what equipment is needed to remove them properly. Their processes help reduce airborne irritants and keep workplaces feeling fresher during the warmer months.”
With the ever-increasing rise in temperature, cleaning routines benefit from a sharper seasonal reset. “Carpets hold onto pollen deep within their fibres so a proper deep clean clears out what winter leaves behind,” Stoltz says. “Air vents and conditioning filters also deserve attention before systems fire back up, because fresh air only works when the pathway stays clean. Shared spaces collect settling pollen quickly so an uplift in cleaning cadence keeps irritants from building momentum.”
Attention then turns to the edges of a workplace where contaminants quietly enter and linger. “Entry mats work hardest at this time of year,” Stoltz adds. “So rotating and cleaning them more often cuts down what travels inside.” Open windows and daylight support healthier interiors by discouraging moisture while blinds, frames and sills reward regular dusting. HEPA grade vacuuming finishes the job by capturing finer particles that standard methods miss.
Bird further advises that maintaining relative humidity between 40 and 60 percent, ideally 50 to 60, reduces both infection risk and mould growth. “Air-conditioning maintenance is a cornerstone of protection, whether systems are ducted or split.”
With warmer periods lengthening, one thing is clear: “We need to think beyond indoor air quality and consider indoor environment quality as a whole,” Bird says. “Temperature, humidity and air all influence health, safety and performance. Understanding that balance is now essential.”
