The rapid spread of the COVID-19 has led many of us to be confined in our homes, working out of a home office. Some of us are with our partners, families, or alone trying to create a normal life and regular working hours. Many of us end up sharing an “office” in a living room, since not everyone can afford to have a separate office room. This blog contains easy tips on indoor air quality to “survive” this confinement and make it as productive as possible.
For those of you lucky enough to have mechanical ventilation, I have just one piece of advice: let the mechanical ventilation run, and probably if you are ALL at home, just set it to “forced mode”. But for those of you sitting in a home office with natural ventilation, good indoor air that promotes efficiency requires a little bit more effort.
1. Keep CO2 levels below 1000 ppm
Human beings and animals breathe in oxygen and exhale carbon dioxide (CO2). This CO2 comes from our metabolism, such as when we burn fat to maintain our body temperature. Thus, our “exhaust gases” — the air we exhale — contains CO2, heat and moisture, just like most other combustion processes.
On average, we produce CO2 at a constant rate proportional to our activity. For instance, when adults work reading or typing in an office, we produce about 16 to 25 litres of CO2 per hour. Children produce a little bit less. CO2 accumulates in the air, and if we have no ventilation, it gets more concentrated. As an example, if two people are sitting in a 30 m2 living room in a house from the 1960s (with small window ventilation openings), it takes about 1.5 hours to increase the CO2 concentration from 400 to 1100 ppm.
CO2 is commonly used as a marker for other pollutants, and many studies relate CO2 over 1000 ppm to 1) Respiratory symptoms, asthma, and allergy symptoms, 2) Airborne infectious diseases and sick leave, 3) Acute health symptoms (Sick Building Syndrome (SBS) and Building Related (BR) symptoms). Additionally, a study from Satish et al. concludes on a significant decrease in work performance when CO2 concentrations are over 1000 ppm and marginal or even dysfunctional levels of performance or decision-making when CO2 levels exceed 2500 ppm, which can happen in just 4.5 hours.
So — open your windows! If there is a significant temperature difference between your “office” and outdoors, typically five minutes is enough. If the temperature difference is smaller, then you need to open your window for longer. If the wind is blowing against your window, just two or three minutes may be enough. If there are more of you in the house, you’ll have to open your window more often, but at least 5 to 10 minutes every hour! So, open the window every hour; small periods usually are enough. This will also help you feel more rested and sleep better.
2. Relative humidity and temperature
In this season of influenza and COVID-19, maintaining the relative humidity (RH) close to 40 % is important, because this affects virus survival. The influenza virus may survive better in colder drier environments. At low relative humidity, it retains its maximum infectivity. World Health Organization officials now say: “The coronavirus can go airborne, staying suspended in the air depending on factors such as heat and humidity.”
This means that the virus can float through the air and infect you even without direct contact or droplets from sneezing or coughing. However, having a high RH (over 60 %) is not good either, because it may cause discomfort connected to inhibiting sweat evaporation. Also, at high relative humidity, we perceive the air as being stuffier and increasingly poorer, probably as there is an increase of VOC emissions (volatile organic compounds), growth of microorganisms (fungi, bacteria, viruses, etc.) and occurrences of allergens.
We human beings produce humidity, and many of our activities produce humidity, including showering, drying wet clothes, cooking, and owning plants and pets.
Thus, we need to ventilate to remove the excess of moisture. In our living room, we maintain an RH about 40 % by opening the windows regularly, as explained before and by maintaining temperature from 20 to 22 °C. If we increase the temperature, we reduce the RH. Also, office workers are shown to perform best at temperatures between 20 and 23 °C.
3. Pollen and road dust
The pollen season has started in Europe. This will not be a surprise for people who are allergic to hazel and birch in Trondheim. Opening windows easily allows pollen and road dust particles in your house. The amount of pollen and particles that comes in depends on the outdoor concentration and the size.
Still, we recommend you open the windows, but if you can, tilt them. If you have allergies, you should always open windows on the leeward side of your house and, if possible, when there is less wind so that the wind will not make the pollen float.The same applies to traffic. Open windows that are farthest away from road traffic. If you are very allergic to pollen, mold spores and dust, you may have to keep your windows closed and run your filtered mechanical ventilation that you probably/hopefully have already installed.
4. Focus on the kitchen
The kitchen is the room that contains the biggest sources of indoor air pollutants. We cook ,which produces moisture; we keep the trash there, which produces VOCs, bioaerosols, bacteria and formaldehyde. We use our toasters and bake in our ovens.
So, if you can close your kitchen door and run the extraction fan, that’s best. If you don’t have a door, because you have an open solution kitchen-living room, remember to run the extraction fan when you are cooking, even if it is noisy, to avoid spreading pollutants to the rest of the house.
5. Keep your house clean and empty the trash
As written above, the trash is a huge source of pollutants. One of the most eminent ventilation researchers, Max von Pettenkofer in 1858, said: “If there is a pile of manure in a space, do not try to remove the odour by ventilation. Remove the pile of manure.”
We need to excel in cleaning. Vacuum clean much more often than you usually do! Clean your work surfaces and also empty the trash more often than you might normally if you might be exposed to pollutants emitted from it. Beyond handwashing to fight the spread of COVID-19 ( DO NOT STOP WASHING YOUR HANDS), having a healthy home office also requires cleaning more often. The virus can spread by direct contact with a surface or object that has the virus.