What field blanks should be deployed to compensate for any background contamination?

Again, this is highly dependent on the research question. Broadly, however, there are 5 types of blanks that should be considered, though some adaptations may be needed, depending on the sample/location/analyte. These are suitably identified in the paper. But, braodly, these should always be present:  
Field blank - designed to detect/quantify contamination from ambient field conditions
Trip blank - the same, but for contamination during trip (may not be necessary)
Equipment blank - assesses how well equipment has been clean and detects residual contamination (probably best suited for analyses such as Pyr-GC/MS)
Procedural blank - as noted, to evaluate contamination from the lab procedures and of reagents.
Blank spike - for recovery assessment. 

These should comprise any equipment/reagents involved in sample collection being sent out at same time as those used for sample collection, handled and exposed to air in the same location and for the same time as collected samples and then returned and processed for MNP analysis along with samples. As noted above, if standard kits for blood sample collection involve plastic, then the extent of sample contamination should be assessed. For example, pig blood should be drawn through the blood sample collection kit used for human sample collection, analysed for MNPs and the results compared to that obtained for the same sample without contact with the sample collection kit.

The field blanks are important for detecting  and eliminating the background contamination during the sampling and handling of microplastic and nanoplastic samples. Some of the most  known and recommended field blanks are air blanks (which could be either open filters or dishes  previously exposed during the process of sampling in order to detect airborne fibers), the container blanks ( usually the ultrapure water is used to detect contamination that could come from packaging materials, shed from plastic lids, labels, bags, etc), the field procedural blanks ( for this, generally are used samples of clean water or  tissues without any microplastic particles that are processed  similar to the investigated samples in order to determine is there are any traces of handling contamination), and transport blanks (those are usually sealed blanks carried  that are investigated alongside the current samples in order to detect  if there was any contamination introduced during the storage time or during the transit). In order to compensate for any background contamination these  types of blanks should be deployed at each sampling site and processed using the same protocols as the actual investigated samples.

This is to be decided on a case by case basis. Especially for biological materials it is very difficult to prescribe the field blanks or even the nature of the field blancs in sufficient detail.

All the collection devices should be tested for background levels of contamination.  Sample storage containers should be tested for contamination.  Suggest that blank sample collection devices and blank storage containers are made available for background testing.  If a field blank is warranted, clean water or a suitable tissue (that is free of MNP) can be taken to the field where samples are collected/harvested, keep the water/tissu open for sometime and analyze in the lab to record background levels of contamination.

If possible, the air of the sampling arena should be sampled. Any flushing or storage media should be sampled. 

Also, a list of all polymer materials used at or near the sampling site would help identify possible background contaminations.

A dummy sample/part/organ which best has similar characteristics to real samples should be deployed and experience the whole process. 

Just as described in the previous section.  In addition, I suggest unused examples of each material used in the medical environment should be collected, stored, and analyzed for polymer ID etc.  This way particles in the tissues can be compared to those items.

Field blanks are for correcting contaminations introduced during sample collection, transport and handling. Typical types of field blanks are air exposure blanks, handling blanks, transport blanks and reagent blanks.