Indoor air quality (IAQ) plays a critical role in ensuring the comfort, health, and psychological well-being of building occupants. Parameters such as relative humidity, CO₂ concentration, and the presence of airborne contaminants are key factors in determining respiratory comfort. But is natural ventilation alone sufficient? In environments where people spend a significant portion of their time, implementing effective air purification strategies is essential.

What chemical compounds are present in indoor air?

Measuring air quality requires specialized instrumentation that is not always readily available. To accurately identify the compounds present in the air, we must rely on standardized parameters and guidelines that help assess whether indoor environments meet safety and comfort criteria. One of the key indicators is air composition — particularly water vapor, referred to as air humidity.

Carbon Dioxide Levels – Measurement:

• Unit: ppm (parts per million)
• Method: Particle count of CO₂ per million air particles
• Standard: There is no unified legal framework for indoor air, but ≤1000 ppm is considered acceptable (atmospheric outdoor air typically contains 350–450 ppm).

Optimal Air Composition for Humans

Over millions of years, Earth’s atmosphere has evolved into its current composition, consisting predominantly of nitrogen (~78%) and oxygen (~21%). In addition, trace gases such as argon, carbon dioxide, neon, xenon, helium, methane, krypton, hydrogen, and water vapor are present. This composition defines what we consider “clean air.” However, modern indoor air is also burdened with anthropogenic pollutants such as ozone, sulfur dioxide, nitrous oxide, soot, particulates, plant spores, and microorganisms — all of which can degrade air quality and negatively impact health.

Two Sides of the Coin

Poor air quality is increasingly prevalent due to urbanization, increased transportation, population growth, and industrial or agricultural activity. In contrast, sparsely populated or natural areas typically exhibit superior air quality — environments where people often go to “breathe clean air” and recharge.

What Does “Ideal Air” Mean?

Imagine a crisp spring morning in the mountains — the air feels fresh, invigorating. Or the unmistakable lightness we feel after a thunderstorm. These sensations are due to the increased presence of negative air ions. The most favorable ionization balance is found near oceans, forests, and mountain peaks. In contrast, modern environments are often oversaturated with positive ions generated by electrical and heating appliances (also referred to as “electronic smog”), contributing to ailments such as headaches, migraines, and joint pain.

Key Factors Influencing Respiratory Comfort

Although respiratory comfort is a subjective sensation, it is strongly influenced by two measurable factors:

• Indoor air temperature
• Relative humidity levels

Recommended Parameters:

• Winter: 18–21°C and 40–60% RH
• Summer: 20–23°C and ≤70% RH

Air that falls outside of these parameters often results in discomfort or even health issues.

We Spend 80% of Our Lives Indoors

Adults spend over half their lives in enclosed spaces — infants, the elderly, and the ill even more so. Children attend daycare, school, and university indoors, and adults work in office buildings and commercial spaces. Increasingly, leisure time is also spent in enclosed environments such as shopping malls, cinemas, or theatres. Given this reality, ensuring optimal indoor air quality is not merely a comfort consideration — it is a health imperative.

How to Ensure Healthy Indoor Air

Breathing is non-negotiable — regardless of air quality, we inhale whatever is present. However, we can take proactive measures to improve the indoor environment. Polluted, allergen-laden air can have cumulative negative effects on health. While we cannot halt urban development, we can mitigate its consequences through effective air purification and ventilation systems — especially in the places we frequent daily: homes, workplaces, hospitals, schools, kindergartens, and public buildings.

Indoor Air Quality and Sick Building Syndrome

In Poland, particularly in older buildings, symptoms of Sick Building Syndrome (SBS) are frequently encountered. Poor indoor air quality is often due to ineffective air exchange and limited air purification capacity. In contrast, modern facilities are equipped with mechanical supply and exhaust ventilation systems powered by rooftop air handling units that provide filtered, fresh air while extracting stale air.

Natural Ventilation Is Not Enough

In many outdated buildings, air exchange relies solely on gravity-based (natural) ventilation, which is often inadequate. This results in insufficient air renewal and deteriorating IAQ. The common assumption that simply opening a window provides clean air is misleading — especially in winter when smog and combustion byproducts enter from outside, and in spring/summer when ventilation introduces allergens, pollen, and street-level pollutants.

Children and Long-Term Exposure to Poor IAQ

From a young age, children are exposed to indoor environments that may pose health risks. They have no control over the air they breathe in schools or nurseries. Poor air quality can lead to long-term health implications for developing bodies. Ensuring safe indoor air should be a top priority not only for parents and educators but also for policymakers at all levels.

Fortunately, awareness of the risks posed by poor indoor air quality is increasing in Poland. Ongoing research, published reports, and legislative discussions in Parliament and the Senate offer hope for meaningful improvement in IAQ standards for enclosed public and private spaces.