It is important to know which air we are referring to
Author: Nebojša Vasilev
Indoor air can be up to 50 times more polluted than outdoor air, according to the World Health Organization. However, we often overlook the quality of indoor air, as we tend to believe that we are more exposed to pollution when we are outside.
One of the reasons for this also lies in the way air quality is reported. When it comes to outdoor and indoor air, we can safely say that they are ‘two different worlds,’ which often collide in public discourse. Why is that?
Governmental stationary monitoring stations of the Environmental Protection Agency measure exclusively outdoor air quality. Their data are presented through the AQI – Air Quality Index, which does not refer to indoor air. Therefore, when air pollution is discussed, it is usually understood as ambient pollution originating from heating sources, industry, and motor vehicles.
However, the real problem of indoor air lies in the fact that the average person spends around 90% of their time indoors. Outdoor pollution only partially penetrates inside, while numerous indoor sources of pollution are generated within enclosed spaces. That is why it is important to clearly distinguish between outdoor and indoor air, their sources of pollution, their impacts, and the ways to address them.
Although the media are full of reports about poor outdoor air quality, information about indoor air quality is almost non-existent, unless we have appropriate sensors at home or at the workplace. Here, we are not talking about devices that only measure temperature and humidity, but about sensors that measure concentrations of particulate matter (PM10, PM2.5, PM1), volatile organic compounds (TVOC), formaldehyde, and carbon dioxide (CO₂) – one of the best indicators of ‘stale’ air in a space.
Outdoor and indoor air are inseparably connected, even though we try to separate them hermetically for energy efficiency reasons. When indoor air becomes ‘stale’ from breathing, it must be replaced with outdoor air through ventilation. That is why it is useful to monitor air quality apps, so we know what we are bringing into the spaces where we spend our time.
It is important, however, to keep in mind that not all AQ apps are the same and to understand that not all data carry the same significance. Some apps display data from official monitoring stations, while others also include measurements from private and public sensors, which can measure both outdoor and indoor air.
Most people do not have experience interpreting the numerical values displayed by AQ sensors, nor are they familiar with the recommendations of the WHO, EU, or local authorities, so air quality is often represented using symbols of different colors and shapes. When this information is presented together without clear context, confusion easily arises – not due to a lack of data, but because of their mixing. In such situations, neither background algorithms, averaging of values, nor additional “smart processing” help. Without proper context, information loses its meaning and turns into a clutter of colorful icons, numbers, and letters.
However, those who become familiar with this data over time can much more easily distinguish between expert and non-expert interpretations in reporting.
When it comes to air quality, a relatively small number of people possess deep expertise, along with broad multidisciplinary knowledge. That is why the long-term work and dedication of experts, combined with the enthusiasm of civic initiatives, represent a valuable resource for society.
The ‘democratization’ of AQ data through the expansion of networks of low-cost AQ sensors and critical thinking does not diminish this contribution – on the contrary, it is a way to protect their work from misinterpretations and sensationalism in widespread use.”
How does polluted air affect us?
When we say that indoor air can be dozens of times more polluted than outdoor air, we primarily mean the combination of human activities and various sources of pollution within enclosed spaces. For example, who hasn’t seen workers grinding, welding, or painting and then taking a cigarette break? Most often, this also involves disregard for occupational safety regulations. Bronchial cancer, by the way, ranks second in Serbia.
Since the coronavirus pandemic, we have also witnessed the emergence of a new epidemic of a different kind – vaping. This new chemical addiction, often presented as a “safer alternative” to tobacco, is aggressively promoted through enticing flavors and scents, especially among young people. Although it is well known that tobacco smoke contains more than 6,000 compounds, dozens of which are carcinogenic, the WHO warns that vaping carries additional risks due to the unknown and non-transparent composition of the liquids.
Whether we are talking about tobacco, vaping, or other sources of pollution, there is no doubt that polluted air negatively affects health – the lungs, heart, brain, and immune system. It can cause both short-term and long-term effects, including weakened immunity and anemia. According to WHO data, more than 3 million people die prematurely each year due to the consequences of indoor air pollution.
What pollutes the air?
Outdoor air pollution mostly originates from the burning of solid fuels for heating, followed by traffic and industry. On the other hand, indoor air pollution is often the result of poor hygiene in enclosed spaces: smoking indoors, inadequate ventilation, failure to extract kitchen fumes, use of harsh cleaning agents, as well as the accumulation of dust from furniture, textiles, and building materials.
When aerosol particles, heavy metals, microorganisms, mold spores, bacteria, and viruses are added to this, it forms a complex and dangerous mixture that our immune system fights against every day.
On average, polluted urban air contains around 100 million PM particles per cubic meter, while our lungs have about 300 million alveoli. Daily, we need approximately 15 kg = 15 m³ of air, significantly more than water – 2 kg, and food -1 kg, which clearly shows the importance of clean air. In nature, the number of PM particles can be up to ten times lower, meaning that our pulmonary alveoli can “rest” there, provided that “urban pollen” has not altered our immune response, so that even nature bothers us. The number of allergic children is increasingly alarming, and we will cover the detailed health effects of polluted air in upcoming articles.
How to improve air quality?
EuroCons Group, in partnership with the Swedish companies Camfil and Munters, has been working for over 20 years to improve air quality through the use of filters for particles, gases, and humidity in industrial, public, and commercial spaces. Our goal is to contribute to raising awareness about the importance of clean air and creating a healthier environment.
That is why we are starting a series of articles in which we will address topics such as:
- how air pollution affects health
- improving air quality in homes
- addressing air quality issues in workplaces
- emission control and reduction of outdoor pollution
- cleanrooms and dry rooms, achieving the highest hygiene standards
- and other related topics
Until next time!
