A study led by researchers at the University of Massachusetts Amherst finds that residential wood heating can reintroduce lead into the air in local communities. The scientists analyze samples of winter particle pollution collected from multiple towns in the northeastern United States and measure markers associated with wood smoke, including potassium, alongside particles containing lead. Across seven winters of data, they report strong associations in several of the towns between daily levels of wood-smoke particles and airborne lead. The pattern is described as showing clear relationships in four of the five original towns, and results are supported by additional statistical adjustments for temperature, which strengthens the conclusion that the added lead is coming from wood burning rather than other sources.
The researchers extend their investigation to additional towns nationwide and find that the strength of the lead-potassium relationship varies by location, with associations reported as strongest in the Rocky Mountains. Although the measured lead concentrations are reported as below U.S. legal limits, the authors emphasize that lead exposure is harmful. The study also suggests that lead may be present in wood due to uptake from soil into tree tissues and then released when the wood is burned, rather than relying on the explanation that lead only comes from waste wood with old lead-based paint.