For mechanical ventilation with dedicated ducting, it seems that in North America, NFPA fire safety rules have deterred the use of polyethylene duct like Zhender’s Comfotube, in favor of fire-rated flex duct like Zhender’s Comfoflex. Brink also has an identical flexible duct.  Both appear to be re-branded versions of Thermaflex S-TL.  While not stated directly, evidence points to this product being made with a vinyl/PVC-coated fiberglass fabric.

This poses some questions about air quality given the possibility of vinyl off-gassing phthalates and other semi-VOCs or VOCs.

At one point, Thermaflex claimed a Greenguard Gold certification for this product but no longer does so.  Notably, Greenguard Gold does not certify the presence of phthalates or semi-VOCs and has a relatively high limit for VOC emission.

Has anyone else researched this or have any direct experience with these products?

Polyethylene tubing does not contain phthalates and has much lower risk of VOC emission, in my understanding.
Are we giving up daily air quality in avoiding the rare risk of ventilation flame spread and smoke generation during a fire?

=== More info ===
Spec sheets for these products, note the images used and specs are identical:
https://thermaflex.net/products/thermaflex-s-tl-flexible-duct/
https://zehnderamerica.com/wp-content/uploads/2014/11/Zehnder-ComfoFlex-05082015-1.pdf
https://cdn.shopify.com/s/files/1/0694/2117/0961/files/Brink_UL_Flex_duct_Spec_sheet.pdf

Thermaflex calls the duct material a “Coated fiberglass woven fabric” and is tight-lipped about what that coating may be.  I did find an old description of the Thermaflex S-LP-10 which states:
JACKET MATERIAL VINYL COATED WOVEN FIBERGLASS
https://www.barobinson.com/buy/product/hvac-flexible-air-duct/470105

This similar product is described as “PVC Coated Fiberglass Cloth”: