Learn ➜ Health Function Scale
Health Function Scale
A separate scale that focuses on how well the material or product performs the health-relevant job it’s made to do.
Dr. Meg Christensen is the physician founder of Interior Medicine, a non-toxic home resource built on her background in medicine, biochemistry, epidemiology, and clinical research.
➜ The Health Function scale is one of the rating systems behind the Interior Medicine Method. See the full methodology for how I evaluate every product.
Published June 1, 2026 | Updated June 1, 2026
Health Function Rating Scale
Most of Interior Medicine rates products on their materials: what they're made of and how those materials affect your health. But some products earn their place in your home by doing a specific job, and that job is itself a health benefit. A blackout curtain's job is darkness, which protects your sleep and circadian rhythm. A shower curtain's job is resisting mold and water. A radon detector's job is catching a colorless, odorless carcinogen before it builds up. When a product fails at that job, the health cost is real, regardless of how perfect its materials are.
The Health Function scale rates how well a product does the health job it exists to do. It runs from Highest to Lowest and stays consistent across every product category, though what earns each tier is defined separately for each one, since blocking light and detecting radon aren't measured the same way. You'll find the specific criteria on each product's page.
Health Function Rating Scale
TIER 01
Highest
Fully performs the health function with no meaningful compromise. The best available option for the job this product exists to do.
TIER 02
High
Performs the health function well, with a minor limitation or tradeoff that keeps it just short of the best available.
TIER 03
Moderate
Partially performs the health function. Workable for many people, but with a real gap compared to higher-rated options.
TIER 04
Low
Performs the health function poorly. Falls short of what the product is meant to deliver for most uses.
TIER 05
Lowest
Does not meaningfully perform the health function. Little to no benefit for the job this product is meant to do.
Categories The Scale Applies To
Currently a work in progress:
Healthy Design for You
Learn ➜ Health Function Scale