With the recent developments of the Coronavirus pandemic requiring many people worldwide to work from home, we at Airthings recognize that now is a pivotal time to ensure your home environment is as healthy as possible. For this reason, we wanted share a little info on an important part of our air that is easily fixed but often forgotten: humidity.
A recent study from Yale University found that low humidity can increase the spread of the flu virus considerably. Cases of flu are undeniably more common in the winter season, but interestingly, it’s not just because of the cold weather. Airthings thinks about air quality every single day, so we are here to break down the facts about humidity and help you breathe better air while you work from home.
90% of our time is spent indoors, what effect does indoor air have on us?
Monitoring indoor air is incredibly important in the modern age. With technological advances, many are now able to work from home. An estimated 54.5% of the world’s population lived in urban settlements in 2016 and predictions for 2030 are at a staggering 60%1. Smaller, more airtight homes are being created to accommodate the increase in the urban population. This combined with the fact that people are thought to spend 90% of their time indoors2, whether that is at work or at home, means healthy indoor air is quickly becoming a priority for many households.
It isn’t just urban areas that are affected. New terms such as home office have been added to the dictionary in recent years to explain the new way in which people work; from the comfort of their own home. The disinclination to take public transport and a long commute, or rare phenomenons such as the outbreak of the Coronavirus have led many to choose this option. In some areas, a temporary home office is even a requirement. Unsurprisingly, this then increases the amount of time we spend indoors and in our homes. Ensuring the air we breathe is healthy is part of living a healthy lifestyle.
During winter we stay indoors and warm up the air inside. In doing so, we dry it out. This reduces the humidity. Whereas in summer the air is naturally more humid and if not ventilated properly mold can form. In fact, 21%3 of the 21.8 million annual cases of asthma are attributable to residential dampness and mold, according to the Harvard Review. Evidently, there are many factors that affect the air we breathe, so being mindful of it is a key part of living a healthy lifestyle in a modern age.
The Research: Humidity and Coronavirus
Low humidity has been linked to the rapid spread of viruses like cold, flu4, and even coronavirus5. The American Society for Microbiology wanted to consider how our built environment (buildings, cities etc) can affect the spread of the virus. SARS-CoV-2 is the official name for the virus, COVID-19 is the name given to the disease caused by the virus.
A possible solution
They suggest “maintaining a relative humidity between 40% and 60% indoors may help to limit the spread and survival of SARS-CoV-2 within the built environment”6. This early research indicates that humidity, especially lower than 40% may help to spread viruses, even SARS-CoV-2 .
Things to consider
In general, recommended humidity levels vary widely. Airthings recommends healthy humidity levels between 30-60% as too high humidity can cause dampness and mold and too low can mean the air becomes dry and uncomfortable. With the newly emerging research, maintaining healthy humidity levels have never been more important.
Remember this is preliminary research, and the knowledge of the transmission of COVID-19 is still developing. We must follow the advice from the Centre for Disease Control and local governments only. It is interesting however to see the research into humidity and coronavirus, and perhaps now is the time to start even more research!
COVID-19: the disease
SARS-CoV-2: the virus7
The research: humidity and flu virus
Previous research for the Centre for Disease Control and Prevention found that when humidity levels were set to a low 23%, a huge 70.6-77.3% of the flu virus particles were able to cause an infection—even an hour after coughing8. To prove the importance of humidity in flu virus transmission further, they also tested humidity levels in a healthier range. By raising humidity levels to 43% they saw a huge improvement. At 43% relative humidity, they found that only 14.6-22.2% of flu virus particles were capable of infecting. They concluded that healthy humidity levels decreased the percentage of flu virus spread.
This startling statistic encouraged much more research into humidity and how it helps to spread viruses. A recent study from Yale University, Department of Immunobiology, found a link between low humidity and the increased risk of contracting flu. Test subjects were “more susceptible to influenza disease” when exposed to low humidity conditions and a controlled strain of the flu virus9. As no changes in temperature had been made, they determined it was the humidity that increased the risk.
The low humidity conditions negatively impacted the immune response in three ways. It “prevented mucociliary clearance”, the natural self-clearing of the airways in our respiratory system, such as nasal passages. Moreover, “innate antiviral defense” and “tissue repair function” were also impaired. Therefore, not only was the spread increased, but the body’s natural defense mechanisms were hindered in fighting the flu virus in environments of low humidity.
In an interview, the lead researcher explains that some age groups are particularly at risk. Our airway cells have cilia, which are “hair-like projections” that move inhaled particles along the airway in order to get rid of them11 In low humidity, she found “this cilia movement as well as the particle removal, was impaired”12. Therefore the low humidity negatively impacted the body's natural defenses. As the mortality of flu mostly occurs in infants and people over the age of 65, this new discovery is particularly useful in helping to protect them.
Interestingly, she believes there is still more research to do in regards to humidity and the effect it has on our immune system. This is because she has found that there is an impairment of the innate immune defense mechanism during her research. Type 1 interferons (which help regulate the activity of the immune system) are important to “induce hundreds of genes” to “counter the virus”13. In low humidity, however, their function is for some reason impaired. The Yale researcher is eager to investigate how the inhalation of air with low humidity impacts the immune defense against the virus.
It is not only humidity that impacts the spread of the flu virus, but it is a factor we can control, at least inside our homes. Considering the findings, maintaining healthy humidity levels is vital to help combat your risk of contracting the flu.
What are healthy humidity levels?
We believe healthy indoor humidity levels are between 30-60%. Humidity levels fluctuate based on daily activities, the seasons, indoor ventilation and more. The problem is finding and maintaining the right balance for your specific home. Too much humidity can cause mold growth. Too little humidity can, as research results indicate, increase the risk of contracting the flu.
Moreover, it is only when humidity levels indoors get really bad that we notice. We know we have high humidity once we have mold growth on our window frames. We know we have low humidity if our skin is becoming itchy and dry, or possibly, if we have contracted the flu. At this point it is too late. That is why using an indoor air quality monitor will enable you to prevent these issues from occurring. Be alerted to when humidity levels rise or fall above the recommended levels, and take action to improve the air you breathe.
How to improve low humidity
Simple fixes around the home can help to improve humidity levels that are below the recommended 30%.
- Washing clothes
When washing your clothes, air dry them inside the house on a clothes rack instead of a tumble dryer or washing line outside. The moisture in the clothes will release into your home.
- Taking a bath
If you take a bath, leave the water in the tub until it cools. Some of the water will evaporate. Naturally if you have small children around, this may not be the best option.
When showering, leave the door open to allow the moisture in the air to pass through the house.
As low humidity is very common in some areas, especially those with colder climates, humidifiers are now used in many people's homes. They are a mechanical device which adds moisture into the air.
- Don't forget high humidity
As we have discussed, healthy humidity is between 30-50%, so above 50% can also cause problems. Find our easy tips on how to improve high humidity, here.
Working from home has changed things. Suddenly juggling work requests from colleagues over skype, finding babysitters (or becoming them) and working out how to turn your dining room table into a workspace have all become an overnight necessity. Though working from home can be irksome, hopefully this deep dive into recent research can help illuminate the best ways to breathe in healthy air at home. With regards to the Coronavirus, the World Health Organisation warns that everyone can be at risk, including those living in hot and humid conditions. For information and support on the Coronavirus, read what the WHO says here.
- Coronavirus disease (COVID-19): for more information on Coronavirus, visit the World Health Organization's information page.
- Type 1 Interferons: “Human type I interferons are a large subgroup of interferon proteins that help regulate the activity of the immune system. Interferons bind to interferon receptors. All type I IFNs bind to a specific cell surface receptor complex known as the IFN-α receptor that consists of IFNAR1 and IFNAR2 chains”14.
- Cilia: Or cilium in the singular, are “minute hairlike organelles, identical in structure to flagella, that line the surfaces of certain cells and beat in rhythmic waves, providing locomotion to ciliate protozoans and moving liquids along internal epithelial tissue in animals”15.
- Relative humidity measures the amount of water in the air in relation to the maximum amount of water vapor (moisture). The higher the temperature, the more water vapor the air can hold.
- COVID-19: the disease
- SARS-CoV-2: the virus7
READY TO MEASURE AIR QUALITY AT HOME?
Buy an Airthings Wave Plus and we will donate $1 to The American Lung Association's LUNG FORCE initiative.
Airthings will donate $1 to the American Lung Association’s LUNG FORCE initiative from each Airthings Wave, Wave Plus, Wave Mini and Corentium Home sold on Airthings.com through October 31, 2020, with a minimum donation of $25,000 to support lung cancer research.