The CO₂ Gas Sensor (CO2-BTA) and Go Direct^® CO₂ Gas Sensor (GDX-CO2) have holes in the shaft of the sensor to allow airflow through the sensing element, however, it is possible for debris or small animals to enter these holes if precautions are not taken. When measuring CO₂ gas from respiration of very small animals such as insects or terrestrial worms, it is possible that the organisms may crawl through the holes in the sensor. This can damage the internal electronics in the sensor and should be avoided. When measuring respiration from a soil sample, take care not to contact the soil with the sensor, and do not invert a container of soil with the sensor in it. We recommend wrapping the sensor in cheese cloth or a fine grain plastic mesh before placing it into a respiration chamber to allow air flow but prevent intrusion of animals or debris into the sensor holes.