Can the air monitoring be performed with both direct-reading instruments and non-direct-reading air sampling methods?
Response: The employer must ensure that conditions in the permit space are acceptable prior to entry and throughout the duration of entry operations [29 CFR 1910.146(d)(5)(ii)]. This is accomplished through the use of test instruments to monitor the atmosphere within the permit space. As described in your scenario, direct-reading test instrumentation may provide adequate air monitoring, as long as all atmospheric hazards are detectable using this method. Question 5: Can workers wear non-direct-reading air monitoring devices, e.g., charcoal tubes attached to low flow pumps and passive badge dosimeters when the employer is first assessing the space to determine if it is a permit-required confined space? Response: If direct-reading instrumentation does not exist for the contaminant to be monitored, then non-direct-reading air monitoring devices are an employer’s only alternative. When first assessing a confined space using such sampling equipment, testing should be conducted without entry
