Temperature and Humidity

By Dan Scungio, MT(ASCP)



Questions about temperature and humidity, especially during the sweltering summer months, are often asked.  What needs to be monitored?  Do I have to wear a lab coat if I'm hot?  What can be done about the humidity in the lab?  It's a broad topic, but thinking in terms of safety and "best practice", the answers are available.


The CAP General Checklist asks if room temperature and humidity are "adequately

monitored" at all times, but that is not very specific.  Not all laboratories require that room temperature and humidity be monitored -  it all depends on what instrumentation exists, on what reagents are stored in the lab, and on what testing is performed.


If instrumentation specifications state optimal temperatures or humidity for performance, you need to ensure that your lab temperature and humidity fall within that range.  I have seen chemistry and hematology instruments fail in the past when air conditioning was turned off after a hurricane and prolonged power outage.  Most analyzers operate under fairly specific conditions - you can find that information in the operator's manual.


If the reagents you store at room temperature have a designated storage range, then you must control and document your temperature.  Some reagents also have humidity specifications, but that is rare.   Some special staining in Histology must be performed under specific temperature and humidity guidelines. There may be other testing in labs that are affected by humidity as well.

As for the monitoring device, several choices exist.  Many electronic thermometers have calibration expiration dates on them.  They can be calibrated annually (with an NIST certified thermometer), sent into the company for calibration, or sometimes it's more cost-effective to simply purchase a new device.  There is no manual calibration that I am aware of for hygrometers, but I believe many models do not have expiration dates for humidity monitoring.  You would need to check with manufacturer instructions.


One more note on "control" of temperature and humidity:  if you have issues with temperature, you need to contact your facilities people to make adjustments so that your testing (and staff) is not adversely affected.  This is fairly easy to do, however, humidity is another story.  Most hospitals and larger facilities have humidifiers and dehumidifiers built into their air-handling systems, but often they are not large enough to handle the building.  In Virginia where I work, our humidity is often too low in the winter and can get too high sometimes in summer months.  We contact the facilities department, but often there is little they can do.  If our analyzers are operating and QC is good, we note that we contacted facilities on our temp/humidity log and move on. CAP inspectors have been comfortable with that as well. 


So when laboratory staff is telling you it's too hot to wear PPE, they may be right.  Don't ignore those complaints or you can help foster an atmosphere of discontent and non-compliance. It is unacceptable for your staff to be working unprotected, but there is no reason your facilities department cannot ensure a comfortable working temperature in the laboratory.  Stay cool this summer- and stay safe.