Ever noticed more sniffles and sore throats when the air feels dry in winter? That’s no coincidence. Dry air isn’t just irritating — it can also reduce your body’s natural defences and make it easier for viruses like influenza to spread.
So, can adjusting your indoor humidity really help reduce colds and flu? According to growing research, the answer is yes. In this blog, we’ll explore the science behind humidity and respiratory health, and how Ionmax solutions can help you maintain the right balance year-round.
What happens in low-humidity environments
When relative humidity (RH) drops — often below 30% indoors during winter — your body’s natural defence systems take a hit:
- Dry mucous membranes: Low humidity dries out the lining of your nose and throat, making it harder to trap and expel viruses.
- Impaired cilia function: The tiny hair-like structures that move mucus and pathogens out of your airways slow down in dry air.
- Weakened immune response: Studies show that dry air can reduce production of interferons, the proteins your body uses to fight off infections.
In short, dry air doesn’t just feel uncomfortable — it helps viruses get a head start.
How viruses behave at different humidity levels
Research shows that many respiratory viruses, including influenza and coronaviruses, survive longer and spread more easily in low-humidity environments.
- A study by Casanova et al., on coronavirus survival found that viruses lasted significantly longer at low RH compared to moderate humidity.
- The same study showed that Viruses tended to survive longer in very dry air (around 20%) and very damp air (around 80%), but they didn’t last as well in moderate humidity (around 50%).
- Research by Lowen and Steel on influenza transmission showed that dry air strongly increased the spread of flu between animals.
This suggests that maintaining moderate indoor humidity can actually make it harder for viruses to survive in the air.
How humidity supports immune defences
It’s not just about the virus — it’s about your body too.
- A Yale study found that mice in low-humidity environments had weaker immune responses, with reduced cilia function and slower lung tissue repair.
- Moist air helps keep mucus in your airways hydrated, which is essential for trapping and clearing pathogens.
Simply put, keeping your indoor air too dry lowers your natural defences.
The optimal indoor humidity range
Most experts agree that the ideal indoor RH for human health is between 40–60%.
- At this level, viruses don’t survive as long, and your airways stay moist enough to function properly.
- Going much higher than 70% can backfire, as it encourages mould and dust mites — common triggers for allergies and asthma.
Maintaining this “sweet spot” is especially important in Australian homes, which can swing between very dry winters (heating) and humid summers.
Practical tips for managing humidity at home
You don’t need to guess whether your air is too dry or too damp — with the right tools, you can keep your indoor environment balanced year-round:
- Use a humidifier in winter to ease dryness and irritation.
- Control excess humidity in summer with a dehumidifier to prevent mould growth.
- Monitor indoor humidity with a device like the Ionmax Q10 Air Quality Monitor to keep levels in the 40–60% range.
- Don’t overdo it — always ventilate your home to avoid stuffiness and indoor pollutants.
For more on mould and air quality, check out our blog: What’s polluting the air in your home?.
Conclusion
Dry air doesn’t just irritate your skin and throat — it can also make you more vulnerable to colds and flu. Research shows that keeping indoor humidity between 40–60% can reduce virus survival, support your body’s immune defences, and improve respiratory wellness.
At Ionmax, we offer a range of humidifiers, dehumidifiers, and air quality monitors to help Australians keep their indoor environment healthy year-round.
Explore the full Ionmax collection and take control of your air today or reach out to us below for free consultation!
