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Low Humidity : Why pesky static shocks can strike health concerns

Relative humidity, or the amount of water vapor in the air, has been associated with health symptoms, air quality and energy consumption.  Although body discomfort and health issues are ordinarily  thought of during  the hazy, hot and humid days of summer, low humidity during the winter months can also cause serious discomfort, low employee productivity and pose other health risks as well.

Colder outdoor temperatures and artificial heat inside cause a drying effect which lowers the indoor relative humidity.  Low humidity in your building, residence or school during the winter months can also increase the incidence of respiratory infections (asthma, bronchitis, sinusitis, etc.), nosebleeds and allergic reactions, exacerbate the effects of exposure to other indoor pollutants such as mold spores, ambient bacteria and particulates such as wood smoke, dust and carbon soot, and has been associated with “Sick Building Syndrome” type symptoms. This is due to dry body surfaces in the eyes, nose and lungs having less resistance to viral, bacterial and mold exposures.  

In one of the largest indoor environmental epidemiology studies, Dr. Cheung and his team were able to show that low humidity was associated with increased respiratory symptom prevalence, increased respiratory symptom days, and multiple respiratory clusters.   Dr. Cheung’s study found that dry air was associated with development of building exacerbated asthma symptoms such as wheezing, chest tightness, shortness of breath and coughing.   Dry air was found to be a common symptom driver. 

Low humidity has long been recognized as associated with dry and irritated mucus membrane of the eye and airway type symptoms. This can be especially problematic for contact lens wearers and those with colds or other airway conditions.

Some groups who commonly exhibit problems with dryness related symptoms include:

  • Contact lens wearers
  • Older individuals who inherently experience decreased tearing due to age
  • Prolonged Computer users, due to reduced frequency of blinking. Because of the combination of concentration on tasks and monitor position, the eyes are also opened wider, creating a greater surface area to be exposed to dryness

Notably, the sensation of dry air is not always correlated with relative humidity – it can be caused by dust and other gaseous air pollutants.  Wolkoff et al., in an extensive review of low humidity and the indoor environment, found that low humidity may have effects on deposition and resuspension of various contaminants and gases that affect the indoor environmental quality.

For maximum comfort and optimal air quality, indoor relative humidity should be below 60 percent (ideally between 30 – 50 percent) at a temperature of 70 degrees.

Currently, indoor humidity is not regulated, however people should be aware of the health concerns and comfort issues that can be associated with low moisture levels. There are many ways to improve low indoor humidity during the winter, such as purchasing a humidity gauge, keeping your body well hydrated and reducing intake of caffeine or alcohol as they can cause dehydration. While humidifiers can increase indoor humidity levels, their usage may cause other health issues unless they are properly maintained. Therefore, humidifiers are not routinely recommended as a long term measure to managing dry winter air.

For more information regarding indoor air quality, how to prevent health risks relating to low humidity, and other air quality issues in commercial, governmental, institutional or residential settings, contact the experts at Cogency at Cogency brings swift focus to office or building environment assessments, with our team of physicians, industrial hygienists and public health professions conducting targeted but thorough building inspections and interviews with affected or potentially affected employees. Cogency has a wealth of experience in diagnosing hard to detect building issues and occupant illnesses possibly related to environmental or toxicologic exposures.

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