Things you need to know about the air we breathe in our homes

In more than two years of living with the pandemic, we've learned to air our homes more and have thought more than ever about what's in the air we breathe.
In truth, viruses are but one of the elements that can contaminate indoor air. But bacteria and other particles of natural origin such as pollen, dust or mold spores are also potential contaminants that can exist alongside the virus itself. In addition, there are particulates - tiny particles produced by human activities such as industry, traffic, various combustions, as well as so-called "volatile organic compounds" (often referred to as VOCs) - chemical substances that can come, for example, from paints or solvents, cleaning products, glues used in furniture and floors that can also play a role in reducing the quality of the air in our homes.
Last but not least, carbon dioxide (CO2) always naturally present in the outdoor air, is also produced by people when they breathe. And although rarely present in dangerous concentrations in homes, it is an easier-to-measure indicator of the concentration of other human bioeffluents, and thus used as a parameter to measure how good ventilation is in general.

In most cases these substances do not have an immediate impact on health, but in the long run they can generate significant damage. According to the World Health Organization, Covid aside, 23 percent of deaths worldwide are linked to spending prolonged amounts of time in unhealthy environments.

"Finally, we should not forget that indoor comfort is also a matter of subjective perception," Babich points out. "It may be that there are no pollutants present in dangerous concentrations either in the short or long term, but that the air is still perceived as stale, perhaps because of odors or humidity that is too high or too low." And yet an American standard gives a clear definition of indoor air quality: according to the ASHRAE 62 standard, acceptable parameters lie in "air in which there are no known contaminants present at harmful concentrations as determined by competent authorities and with which a large majority of 80 percent or more, of exposed persons do not express dissatisfaction”.

First of all, keep in mind that a specific purifier does not remove all air pollutants. It is therefore very important to know which pollutants present high concentrations and then choose the right purifier accordingly, also one must consider the size of the room.
Also keep in mind that some purifiers are mechanical and use high-efficiency particulate air (HEPA) filters for example while others use different solutions such as ionizers and ozone instead. In general, mechanical purifiers are preferable. Other types might lower the level of a certain pollutant, but at the same time generate new ones.
However, before even thinking about purifiers, there are some simple and valid actions that those who live in the house can undertake: avoid smoking indoors, turn on extractor hoods when cooking, ventilate the house properly if you have many guests for example, it is better to increase mechanical ventilation or open the windows a little more. And if possible, opt for low-emission furniture which are becoming increasingly available -some manufacturers now provide additional certifications that go beyond the minimum standard requirements. In some cases, it is also worth rethinking the way in which your furniture is arranged: if you suspect that a low-quality shelving unit could present a source of formaldehyde and you cannot replace it, the least you can do is place it somewhere not continuously exposed sunlight.
Other solutions concern the design of the house.

Although older homes often have air infiltrations that are a problem from an energy standpoint, they do tend to circulate more air. And though this can help dispose of pollutants generated inside, it is still not an optimal solution, because you have no control over infiltration, which can vary greatly. Newer homes are usually optimized to save energy and are therefore more airtight. This is where the motto "build tight, ventilate right" comes into play.
"Saving energy is essential, but it's not enough," explains Eurac Research’s Roberto Lollini, engineer and head of the Energy Efficient Building research group. "You have to feel good in your home, and for some time now, our research has been about combining these two dimensions."