Indoors and outdoors, air pollution is caused by the presence of contaminants that damage our health. These contaminants can be physical, chemical, or biological. 

Outdoor, or ambient air quality issues have been known, publicised, and regulated for decades, but the problem of indoor air pollution entered into the debates more recently, in the mid-2000s.

But what do we mean by "indoor air"?

Indoor air quality refers to the air that occupies confined, non-industrial environments—whether private (housing, offices, car interiors) or public (public transport, schools, public places, etc.).

These indoor spaces are often found to be contaminated by many pollutants, and studies even show that indoor air pollution is up to 8 times greater than that of outdoor air. Why is indoor air quality important? We spend, on average, 80 to 90% of our time inside! So, although ignored for a long time, the question of indoor air quality has become one of the main environmental public health issues all over the world. 

What are the pollutants that affect our indoor air quality?

First of all, outdoor air pollutants (NO2, particles, ozone, etc.) are not like vampires. They do not wait for you to invite them in! Some pollutants, like ozone, even react with materials in our homes to generate a new cocktail of pollutants. If the indoor space is poorly ventilated, pollution can quickly accumulate, especially in small spaces like inside cars, bathrooms, and garages.

However, pollution in confined spaces is usually very specific and, once the source has been identified, can be eliminated. There are multiple sources of indoor pollution and they can be linked to: 

  • human activities (use of cleaning or cosmetic products, cigarette smoke, cooking food, candles, incense…)
  • equipment and buildings (furniture, defective ventilation systems, glues, varnishes, paints, coatings, asbestos, building materials…)
  • when the premises are occupied (animals, plants).

These different sources of indoor pollution can generate dozens of chemical substances which are grouped under the name Volatile Organic Compounds (or VOCs). VOCs are emitted in by products such as cleaners or cosmetics, or by combustion (smoking, candles, incense, etc.). 

These substances have various health effects, which can cause headaches and eye irritation in the case of short exposure, but can also be linked to respiratory problems and they can even affect the hormonal system in the event of long-term exposure. Among these pollutants, some, such as formaldehyde or benzene are classified as carcinogenic by the WHO.

How to improve indoor air quality?  

Ventilating confined spaces is fundamental to maintaining good indoor air quality. This helps prevent pollution from accumulating and keeps air clean. It’s best to ventilate indoor spaces when the air outside is cleanest (often in the morning and evening). 

It is also essential to limit the use of harmful products indoors. This means learning about the ingredients and composition of the products we use every day. It’s also important to follow a few simple rules like no smoking inside and going without candles or incense.

It’s possible to measure the air quality at home and see its evolution by investing in personal air quality sensors like Flow, which help assess the air quality both indoors and outdoors.