Relative Humidity – An Important Factor for Good Indoor Air Quality

I retired in 2012 after twenty-four years as a pharmacist in central Florida. As we got into the winter season every year, I have had plenty of requests for humidifiers, mostly from parents of sick children. While it’s almost a tradition to run a humidifier for a sick child, especially in the winter months, it can at times be counter-productive and make things worse.

The reason a humidifier is in the winter as it gets colder, there is less water vapor in the air. The cold air causes it to condense into liquid water, making the air drier. When a home is heated without adding the moisture back in, relative humidity (RH) drops. For example, air that has an otherwise comfortable 50% RH at 50 degrees F. drops to a very dry 25% RH when heated to 77 degrees F. The way to correct this is to run a humidifier to add moisture back into the air.

Here in central Florida, we have a unique problem. Relative humidity remains relatively high during the cooler months and we don’t need to run the heat very much. Except for the coldest days, RH inside the home can get into the 60% plus range because we also aren’t running the air-conditioner much, if at all. It can be even higher on those rainy or just cloudy days. Running a humidifier can make air quality worse, which will increase the risk of mold, bacteria and virus growth, increasing the risk of respiratory problems.

On high humidity days, running a de-humidifier is the way to correct it. Don’t have one? Here is an easy way to do it the relatively few times a year it’s an issue. Just lower the a/c setting one degree below the current room temperature. Then kick on the heat for a short time if that makes it a little too cold. Repeat as necessary. Sure, that adds a little extra to your electricity bill, about 25 cents per hour. But it’s cheaper than some sick days from school or work, doctor visits, and medication.

The best way for us to manage this in our homes here in central Florida is to purchase a humidistat. It’s a simple device that measures relative humidity. One can be purchase on eBay for as little as $5. Just search, “digital humidity meter”. Then keep the relative humidity in a comfortable range of 45% – 55%. When it gets too high, 60% or more, just run the a/c some. Too low, then turn on that humidifier. That will keep your home comfortable and healthy for the whole family.

Thomas Scott, REALTOR®, GRI®, R.Ph.
Operations & Marketing Manager
The Jean Scott Team

407-559-4880
Tom@JeanScottHomes.com

Keller Williams Advantage Realty
1351 Alafaya Trl Ste 100
Oviedo, FL 32765