Relative Humidity Assessment – How It Influences Your IAQ

Seeking to improve the comfort of your indoor environment, several different parameters can be changed and manipulated to conditions that are a better fit for human comfort. Among these parameters, relative humidity has become one of the essential elements that individuals, companies, and industries alter and adjust constantly to improve the environmental comfort. However, changes in relative humidity can also lead to other secondary reactions in your closed environment that can compromise your health in ways that are not immediately perceived. To ensure that your air quality is within safety and comfort levels when considering relative humidity is important to understand fully how this parameter affects both your health and the quality of your indoor air.

What is Relative Humidity?

Relative humidity is a parameter based on the presence of water vapor in the air. Humidity, which is the amount of particles of water in suspension in the air leads to relative humidity by relating the ratio between the current absolute humidity and the highest possible humidity (100%). It can be easily calculated by:

In practice, this means that once you find a relative humidity of 100%, the air does not allow for any more water to be vaporized, risking to saturate to the point of rain. Therefore, rain occurs when the air around the clouds is saturated to 100% and water vapor condenses and forms droplets that fall to the ground, due to the increase of density.

For humans, relative humidity affect directly our sense of temperature comfort. When the air is relatively saturated with water molecules, the sweat produced by our bodies does not evaporate, which compromises our natural cooling down system. On the other hand, when relative humidity is low, our sweat will evaporate easily and contribute to effectively cooling down the organism.

How can I control relative humidity?

Relative humidity naturally fluctuates throughout the day and within seasons both indoors and outdoors. On average, keeping relative humidity indoor between 40 and 60% ensures body comfort, while also avoiding other side effects of both high and low humidity.

Nowadays, most electronic devices that control and maintain air temperature are equipped with relative humidity measurements that allow for a constant assessment of the conditions indoor. However, when relative humidity is either too high or too low, certain changes in the environment can be noticed:

  • For high relative humidity: condensation points on windows, moisture formation and occurrences of mold on walls and ceiling can be noticed.
  • For low relative humidity: static electricity, cracking millwork and paint are an indication of humidity beyond comfortable level.

Similarly, to improve indoor air comfort, relative humidity can be increased or reduced according to the specific need of each room. In the case of relative humidity that is too low, efficient solutions are:

  • Adding potable humidifier in the room
  • Increasing humidity through natural evaporation, placing a water vase in the room
  • Installing whole house humidifier

In case of relative humidity that is too high, it is recommended to:

  • Turn off humidifiers in the room
  • Use dehumidifier
  • Install and use exhaust fans in cooking areas
  • Cook with covered pots, shifting clothes dryer vents to the outside and reducing the number of plants in the house

What are the health effects caused by inadequate relative humidity indoor?

For human comfort and safety, relative humidity should be kept between 40 and 60% indoors. In cases where these values vary certain side effects compromising human health can be seen. For areas where the relative humidity is low, cases of dryness of the skin followed by itchiness are noted. In cases where the relative humidity is extremely low (under 20%), the contact with the dry air might cause drying up of the bronchial mucous which can lead to other health problems in the respiratory system.

However, several other health issues can arise from relative humidity above recommended levels. With high relative humidity, the temperature comfort in the room will change and individuals will report feeling cold or sticky in cold and warm weather respectively. Other problems that arise with high relative humidity are:

  • Increased growth of mold and bacteria that cause respiratory problems
  • Enable dust mites growth which cause asthma attacks
  • Enable fungal growth which might cause bad odours and create discomfort
  • Can cause additional breathing problems for sensible individuals

What causes shifts in relative humidity?

Relative humidity can shift to lower or higher than desired levels due to a series of different events. For cases of relative humidity lower than recommended, high temperatures, dry currents and lack of water reservoirs in the area can all be causing the marked lower relative humidity.

However, cases of high relative humidity are more frequent than lower relative humidity and commonly reported in urban areas due to excessive use of air conditioners, indoor cooking and poor dimensioning of airflow systems. Here, the most common causes of high relative humidity indoors are:

  • Indoor cooking without proper exhaustion
  • Water leakage in the building
  • Damp ground under the building structures
  • Retained moisture from construction areas in the building
  • Plumbing leaks

How can I monitor the relative humidity indoors?

Relative humidity has become an important parameter to assess indoor and many companies have now provided devices that focus on sampling the air for relative humidity and deliver the information coupled with temperature measures. Additionally, several humidity sensors are available commercially that provide a simple and concise reading of the information.

For more advanced housing devices, thermostats and humidity measurements can be coupled to smart house controls mounted on the wall informing the relative humidity in each room. Moreover, these devices can be coupled to wireless data distribution and keep an up to date information on the relative humidity of each indoor area avoiding the persistence of undesired conditions in areas that have a lower circulation of individuals.

How can IAQ help?

IAQ focuses on ensuring the safety of your indoor air quality guaranteeing that your environment is proper for housing and working conditions. With this focus, IAQ cherishes for a high-quality standard operation and quality control of all parameters analyzed during indoor air quality assessment. Within the parameters analysed, relative humidity is taken into account due to the considerable health hazard caused by submitting individuals to environments operating without recommended conditions.

By assessing the relative humidity of our indoor air quality, IAQ ensures that a qualified team is sent to your location and carries out a thorough assessment of the entire building identifying areas with variable relative humidity and the possible cause for these variations. IAQ also provides a detailed report on the main causes for this variation of relative humidity and possible consequences that might implicate structural damage for your building, alongside a health risk for the individuals who circulate through it.

Finally, as relative humidity is one of the major causes for the incidence of mold and other microorganisms that can represent a health risk to you and your family, IAQ relies on a specialized team able to sample and analyze the quality of your indoor air. Through gas, dust and surface analysis, IAQ is able to point out problem areas in your house or building that might be affected with mold infestation and represent a further risk to the occupants of these areas. With a highly specialized team, IAQ is able to evaluate the quality of your indoor air ensuring that all causes are addressed and the problems identified are properly solved.


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