Creating a TB laboratory temperature and humidity daily log

Temperature and relative humidity records are simple quality tools, yet they can reveal problems before they affect tuberculosis testing, specimens, reagents, instruments or staff safety. A well-designed daily log shows whether critical rooms remain within defined operating conditions and provides evidence that the laboratory is monitoring its environment consistently.

For TB laboratories, environmental monitoring should be practical enough for busy staff to complete every day. The record needs to identify the room, the measuring device, the person taking the reading, the time of observation and any action taken when results fall outside the approved range.

Australian laboratories may operate in very different conditions. A facility in Darwin can face persistent high humidity, while a laboratory in inland New South Wales may experience dry air and large temperature changes. Regional services may also have fewer technical staff, so the process should remain clear when the usual quality officer is away.

The log is most useful when it forms part of a broader quality management system rather than sitting as an isolated sheet on a clipboard. It should connect with document control, equipment maintenance, internal assessment, incident management and continual improvement, including the practical resources available through the GLI Quality Tool.

Identify rooms and activities that need monitoring

Begin by listing rooms where temperature or humidity can influence testing, containment, storage or equipment performance. Depending on the laboratory design, this may include the specimen reception area, processing room, microscopy room, molecular testing room, culture area, media preparation space, reagent store and rooms containing refrigerators, freezers or incubators.

Do not assume that every room needs the same limits or the same monitoring frequency. A reagent store may require stable temperature, while a room containing sensitive electrical equipment may need humidity control. The laboratory should consider manufacturer instructions, validated procedures, biosafety requirements, local building conditions and the risks associated with a loss of environmental control.

The record should be linked to a room code or clear location name. “Lab 2” may be understood by regular staff but create confusion during an audit or after a relocation. A description such as “TB culture processing room – Building A, Level 1” is easier to trace in maintenance records, corrective actions and facility plans.

This risk-based approach aligns with the first stage of establishing a quality system. Laboratories can use the phase one roadmap to review their current arrangements, identify gaps and set priorities before introducing new forms or monitoring devices.

Set defensible temperature and humidity limits

A daily log should state the acceptable range directly on the form. Staff should not have to search through a procedure or ask a supervisor whether a reading of 26 °C or 70 per cent relative humidity is acceptable. Include the lower and upper limits, the unit of measurement and the response required when a limit is exceeded.

There is no universal range suitable for every TB laboratory room. Limits should come from equipment and reagent manufacturer instructions, validated methods, facility risk assessments, occupational health and safety requirements, and any relevant laboratory or accreditation expectations. The laboratory may set an alert limit that prompts review before an action limit is reached.

Record temperature in degrees Celsius and humidity as relative humidity, abbreviated as %RH. Use the same format throughout the document, such as “22.4 °C” and “51 %RH”. Avoid mixing Fahrenheit, Celsius, decimal commas and decimal points, since inconsistent notation can make trend review and electronic data entry harder.

The procedure should explain what happens if a result is out of range. Possible steps include checking the reading, confirming that the door is closed, moving vulnerable materials to an approved location, notifying the duty supervisor, contacting facilities staff and assessing whether testing or stored materials were affected.

Design a log that staff can complete quickly

A useful paper or electronic log contains enough information for traceability without becoming burdensome. At a minimum, include the date, room, time, temperature, relative humidity, staff initials or signature and a field showing whether the result is within range. If one device monitors several rooms, record the instrument identification as well.

Add a space for comments and actions. A note such as “high humidity – dehumidifier restarted, supervisor notified, repeat reading 30 minutes later” is far more valuable than a tick in a box. If the result is acceptable, a short “within limits” entry may be sufficient where the form already displays the approved range.

The form should include document control details: document title, form number, version, effective date, page number and approval status. Retain completed logs according to the laboratory’s record-retention procedure. Do not leave loose pages in an unlabelled folder, particularly where several rooms and instruments are involved.

An electronic form can improve legibility and make trend analysis easier, but it should not introduce unnecessary complexity. In a regional or remote Australian service, a controlled paper form may be more reliable than a cloud application that depends on an intermittent internet connection. If paper is used, define who transcribes, reviews or archives the records and how corrections are made.

Choose, place and verify monitoring devices

Use a calibrated thermometer and hygrometer, or a combined data logger, that is suitable for the expected environmental range. The device should have a unique identification number, a calibration status and a defined recalibration or verification interval. Keep calibration certificates and service records with the equipment file, not attached permanently to a daily sheet that may be discarded.

Placement affects the quality of the result. Avoid positioning the sensor directly beside an air-conditioning outlet, heater, window, exterior wall, incubator or other heat-producing equipment. Place it where readings represent the room environment relevant to work and storage. If a room has known hot or damp zones, perform a mapping exercise before selecting the routine monitoring point.

A busy laboratory in Brisbane may need to consider air-conditioning cycles and seasonal humidity, while a facility in Perth may see different conditions during hot, dry periods. In Australia, the Bureau of Meteorology provides useful seasonal context, but the laboratory’s own validated monitoring records must determine whether its rooms remain suitable.

Staff should be trained to allow the display to stabilise before recording a reading. They should know how to recognise a low battery, a disconnected probe, a frozen display or an implausible result. A second device or independent check may be needed when the primary monitor appears unreliable.

Establish a consistent daily reading routine

Write the monitoring frequency into the relevant standard operating procedure. “Daily” should mean something specific, such as once during each operating day at a defined time or once per shift. If conditions change quickly, daily checks may be insufficient and an automated logger or additional readings may be justified.

Take readings at a time that reflects normal laboratory operation. Recording immediately after doors have been open for specimen movement may produce a different result from recording before the room is used. The selected time should be practical, repeatable and documented so that trends can be interpreted correctly.

Assign responsibility by role rather than relying on one person’s memory. The duty technologist, specimen reception officer or shift lead may complete the reading, while the section supervisor reviews exceptions. Include a handover process for weekends, public holidays, leave and roster changes. This is particularly important for smaller services supporting remote communities across large distances.

Review the log at a defined interval, such as weekly or monthly. Look for gradual warming, repeated high humidity after rainfall, missing entries, readings made at unusual times or frequent excursions linked to equipment use. A trend can be an early warning even when every individual result remains within the stated limits.

Investigate excursions and connect records to improvement

An out-of-range reading should trigger a documented response, not an erased value or rewritten entry. Staff should record the original result, the time, the verification check, the person notified and the immediate control applied. Corrections on paper should remain traceable, with a single line through the original entry, the corrected value, initials, date and reason.

The supervisor should assess potential impact. Consider whether specimens were exposed, whether reagents or controls were stored in the affected room, whether instruments were operating during the excursion and whether the condition lasted minutes or several hours. The decision may involve repeating a test, quarantining materials, checking storage conditions or consulting a technical specialist.

Environmental problems may point to building or equipment failures. A failing air conditioner, blocked ventilation grille, poorly sealed door or overloaded refrigerator can create repeated excursions. Corrective action might include facilities work, relocation of materials, revised cleaning schedules, alarm installation or a change to the monitoring point.

Temperature and humidity records should be reviewed alongside other quality indicators. If the laboratory also monitors bacterial contamination, environmental events may help explain unexpected findings. The contamination monitoring guide offers related practical guidance for laboratories developing a structured approach to contamination risks.

Control the form and use it during assessment

Include the daily log in the laboratory’s controlled document system. The associated procedure should define the purpose, scope, responsibilities, equipment requirements, acceptable ranges, reading schedule, escalation pathway, record storage and review process. Staff training should cover both completion of the form and the actions required when conditions are unsuitable.

Internal audits should sample completed logs from different rooms and dates. Check whether entries are complete, whether the measuring device was in calibration, whether exceptions were investigated and whether actions were closed. An auditor should be able to follow the path from an unusual reading to the final decision about affected work or materials.

Use the results to improve the system. Repeated missing entries may indicate that the form is too complicated or that responsibility is unclear. Recurrent humidity excursions may justify a facilities project or a different storage arrangement. A new molecular testing room may require revised limits, another monitoring point or a separate form.

The GLI checklists can help laboratories review documentation, equipment, assessment and continual improvement activities across their quality management system. Adapt any checklist to local procedures and the actual risks of the facility rather than treating it as a substitute for professional judgement.

Create the log, approve the limits and train the staff who will use it. Start collecting readings in each critical room, review the first month for practical problems and document every excursion clearly. A consistent record turns room conditions into usable evidence, supporting safer TB testing and a more reliable laboratory quality system.