Why Indoor Air Feels Worse Than It Used To

Many people describe the same experience in modern indoor spaces: reduced concentration, persistent fatigue, headaches, or a general sense of discomfort that is difficult to explain. These effects are often attributed to stress, workload, or screen exposure. Far less often is the air itself considered as a contributing factor.

Yet indoor air today is materially different from the air people experienced even a few decades ago. This change is not driven by a single pollutant, but by a combination of design choices, building practices, and lifestyle patterns that have quietly reshaped indoor environments.

Understanding why indoor air feels worse requires examining how spaces are built, used, and ventilated in practice, rather than how they are assumed to function.

Buildings Are More Efficient and Less Permeable

One of the most significant shifts in indoor environments has been the pursuit of energy efficiency. Modern buildings are designed to minimise heat loss, reduce uncontrolled air leakage, and maintain stable internal temperatures.

These goals are achieved by:

• tighter building envelopes

• sealed windows and façades

• controlled mechanical ventilation

• reduced reliance on natural airflow

While these measures improve energy performance, they also reduce passive air exchange. As a result, indoor air is refreshed less frequently unless ventilation systems are explicitly designed and operated to compensate.

Air that once diluted naturally now circulates within a more closed system.

Indoor Pollution Sources Have Increased

At the same time that buildings have become more sealed, the number of indoor pollution sources has grown.

Common contributors include:

• cooking appliances and high-temperature food preparation

• cleaning products and air fresheners

• furniture, flooring, and finishes that off-gas VOCs

• electronics and office equipment

• higher and more consistent occupancy

Individually, many of these sources appear insignificant. Collectively, they introduce a continuous background load that accumulates in poorly ventilated spaces.

Indoor air is no longer a filtered version of outdoor air. It is an environment with its own emission profile.

Ventilation Is Often Designed for Assumptions, Not Reality

Ventilation systems are typically designed around expected occupancy, usage patterns, and regulatory minimums. In reality, spaces are often used more intensively and more flexibly than anticipated.

Examples include:

• meeting rooms used continuously without breaks

• bedrooms occupied for longer periods with closed windows

• home offices repurposed from spaces not designed for work

• classrooms and shared spaces operating at or above capacity

When real-world use exceeds design assumptions, ventilation becomes insufficient even if systems are functioning as specified.

The result is gradual degradation rather than sudden failure.

CO₂ and Air Stagnation as Early Indicators

Carbon dioxide levels often rise first when ventilation is inadequate. While CO₂ itself is not harmful at typical indoor concentrations, it is a reliable indicator of air stagnation and insufficient fresh air supply.

Elevated CO₂ levels are frequently accompanied by:

• accumulation of fine particles

• persistence of VOCs

• increased humidity

• reduced perceived air freshness

This combination affects comfort and cognitive performance even when pollutant levels remain below regulatory limits.

Air does not need to be “unsafe” to feel detrimental.

Standards Prioritise Compliance Over Experience

Most indoor air standards focus on minimum acceptable conditions rather than optimal ones. They are designed to prevent acute harm, not to guarantee comfort, cognitive clarity, or long-term wellbeing.

As a result:

• short-term spikes are averaged out

• cumulative exposure is underrepresented

• interactions between variables are ignored

• occupant experience is treated as subjective

Spaces can meet standards while still producing persistent discomfort.

Time Indoors Has Increased

People now spend a larger proportion of their time indoors than ever before. Work, leisure, rest, and social interaction increasingly occur in enclosed environments.

This increased exposure time amplifies the effects of modest air quality degradation. Conditions that might have been tolerable for short periods become consequential when experienced daily.

What once felt acceptable now feels exhausting.

Why the Change Is Being Noticed Now

The perception that indoor air feels worse is not necessarily due to a sudden deterioration in all spaces. It reflects a combination of increased exposure, reduced ventilation resilience, and higher expectations for indoor environments.

As people become more aware of how environment influences performance and wellbeing, air quality shifts from background condition to limiting factor.

The air has not simply changed. Our relationship with it has.

From Passive Assumption to Active Variable

For much of history, indoor air was treated as passive and static. Modern environments reveal that it is dynamic, activity-driven, and highly sensitive to design and usage patterns.

Recognising this does not require alarmism. It requires measurement, context, and an understanding of how air behaves over time.

When indoor air becomes visible, it stops being mysterious and starts becoming manageable.

Why This Matters

Indoor air quality influences how people think, work, rest, and recover. Treating it as an afterthought limits the potential of indoor spaces.

Understanding why indoor air feels worse than it used to is not about nostalgia. It is about recognising how modern environments function and adjusting expectations, design, and monitoring accordingly.

Air is no longer just background infrastructure. It is an active component of daily life.