Is 70 Percent Humidity High [Outside & In The House]?

Liz Yang

Every so often, we have to decide if a specific relative humidity (RH) is too high or too low for us, our pets, or our house. Humidity is such an essential factor that can affect our comfort, health, and the safety of our home. 

Is 70 percent humidity high outside or in the house? While 70% relative humidity can promote dust mites and mold growth indoors, you can feel comfortable outside with the same RH as long as the dew point is between 55 to 60 degrees Fahrenheit.

Not everyone is a meteorologist that can easily understand this short answer. Don’t worry! I will touch on all the conceptions in it and explain how a 70% humidity will affect your life.

Is 70 percent humidity high outside?

is 70 percent humidity high outside

It depends. When RH outside is 70%, you can still feel comfortable when the dew point is about 60 degrees Fahrenheit. RH is not the best metric for making judgments.

Despite many people using relative humidity to estimate whether the environment is too humid or not, it is not as accurate as it seems.

When we go outside, the most important thing for us is whether or not we feel comfortable in the environment, and the dew point is the best indicator of how “dry” or “humid” it will feel rather than RH.

It means that you can feel great when the RH is as high as 100% as long as the dew point is in the proper range. 

Why dew point matters more than relative humidity?

Relative humidity describes the percentage of the amount of water vapor in the air compared to the amount of water needed to achieve saturation at a particular temperature. 

The higher the temperature, the more water the air is able to hold. Hence, the absolute amount of water vapor in summer is higher in winter with the same RH.

Dew point is the temperature that the air needs to achieve in order to let the RH become 100%. At this point, water vapor can turn to liquid form. The higher dew point often indicates that more water vapor is in the air and the temperature outside is higher, which can directly affect our feelings. In general, you will feel the humidity is too high whenever the dew point is above 70 degrees. 

When can 70% RH be high outside?

Usually, the higher the temperature outside, the more likely that you will feel 70% RH is high.

According to this calculator, when the temperature is 70 degrees with 70% RH, the dew point will be 60 degrees which is excellent. However, when the temperature is 80 degrees with the same RH, the dew point will increase to 70 degrees which we will feel too humid. 

So 70% RH can be high outside in summer but is a proper RH in autumn and spring.

Is 70 percent humidity high in the house?

Is 70 Percent Humidity High in the house

Yes, 70% humidity in the house is high. The dust mites, mold, and some bacteria will thrive, and the wood will swell and warp at such humidity levels, putting your health and home at risk.

When we go outside, we don’t need to care too much about the ventilation, the growth of microorganisms, and the condition of the furniture as we do in the house. So the dew point is a great indicator to look at. 

However, relative humidity turns out to be essential for judging the humidity indoors because RH can affect the conditions of many substances in the room, and these substances will pose risks to us.

According to the Environmental Protection Agency, the ideal indoor RH falls between 30% to 50%. Consequently, 70% is too high for our human beings. 

Side effects of 70% indoor humidity

Threaten your health

The most common place to find mold in your home is the bathroom since it is humid due to its function. 

Mold and dust mites start to thrive when the humidity level is above 60%. When the humidity level goes up to 70%, you are expected to live in a room that is full of these harmful microorganisms. 

Don’t neglect the effect of these contaminants in the air. They keep looking for new residences and will get into your body when you breathe, causing allergic reactions, asthma, breathing difficulties, and even asthma flare-ups. 

Damp air can also attract bugs and roaches, leading to other health problems.

Except for the effect of these creatures, if the temperature is high in the house with a humidity level of 70%, you will feel uncomfortable since the dew point is also high at this moment. The sweat will not evaporate very fast, and your body can’t cool down. 

Damage your furniture and house

Many houses are made of wood components and have wooden furniture in each room. Wood is a material that is sensitive to humidity changes. 

When the air is too damp, condensation will form on the window and other surfaces, resulting in mold growth. Meanwhile, wood will continue to absorb moisture, which will swell. 

If wood furniture is exposed to this environment for a prolonged time, it will not be able to return to its standard shape, leading to warping and splitting. If it happens to wooden parts of your house structure, it can threaten your safety.

How to lower the humidity in the house?

While you can’t control the humidity outside, you can regulate the level of humidity in the house. 

At first, you have to monitor the humidity level through a hygrometer or using other methods. Don’t wait until the humidity level rises to 70% to take action. As long as it gets close to 50%, you should turn on your dehumidifier or air conditioning.

Air conditioning is an excellent option if you have a sufficient budget. It can effectively remove the moisture and cool the room. Or you can use a dehumidifier instead. 

Conclusion 

This post discussed whether or not 70 percent humidity is high outdoors and indoors.

In the house, 70% humidity is high because it boosts the growth of dust mites and mold and causes warping in the wood.

However, 70% humidity is not always high outside. You can still feel comfortable in such humidity if the temperature is relatively low. When the temperature goes up to a certain level, 70% humidity could be too high. In other words, relative humidity is not a suitable indicator to describe your feeling outside, and the dew point is a better one.

Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested a lot of products in person, like humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.

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