What Is a Comfortable Humidity Level Outdoors?


A relative humidity level between 45 to 55 percent is considered comfortable for most people. Humidity levels are variable from place to place, as well as from season to season. It is important to ensure that you are aware of the humidity levels both in the environment and in your home, as high or low relative humidity levels can cause negative health effects.

Humidity levels measure the amount of water vapor in the air around us. There are two ways to measure humidity: absolute and relative humidity. Absolute humidity simply measures the level of water vapor in the air, while relative humidity measures the ratio of the absolute humidity level to the highest possible absolute humidity level for the current temperature. Warmer air is able to hold more water vapor than cooler air.

As more and more water vapor collects in the air, the relative humidity level moves closer to 100 percent. When clouds form rain it means that the humidity level within the cloud has reached 100 percent, and the air must expel the excess moisture in the form of rain. 100 percent humidity at the ground level can also mean that rain is in the forecast. However, rain at ground level does not necessarily mean that the humidity level in that area is at 100 percent.

While many people consider temperature to be the primary factor that determines their comfort level, high or low levels of relative humidity can significantly alter how comfortable we feel. Coupled with high temperatures, high relative humidity can be dangerous for children and the elderly, as the body has a harder time cooling off when both the temperature and humidity levels are high. Humans sweat to prevent our bodies from overheating in hot temperatures, and additional water vapor in the air can prevent sweat from evaporating off of our skin, causing us to remain overheated.

Similar to the effects of high humidity, low relative humidity levels can make you feel like the air is cooler than it actually is. Low relative humidity can also be a trigger for health issues. Cold winter air can hold significantly less water vapor than warmer air, causing the air to feel dry in the winters. The combination of cold air and low relative humidity can cause respiratory problems, dehydration, dry and itchy skin and a higher likelihood of contracting colds and other illnesses.

Your home environment is also susceptible to the effects of both high and low humidity. If, during the summer, the interior of your home has a humidity level higher than 45 to 55 percent, there is a higher chance of mold growing in your home. If during the winter months the air in your home has a low relative humidity level, there is an increased chance of wood floors or surfaces shrinking and warping and fungi growing in the house’s structure.

In order to keep your home at a comfortable humidity level year round, use a humidifier in the winter, when the humidity level is low. Living house plants can also help raise the humidity of a home, as can placing containers of water near your heat ducts. If the relative humidity level of your home is high in the summer months, consider use a dehumidifier, an air conditioning system, or exhaust fans to bring the humidity levels back into the 45 to 55 percent range.