Respiratory Deposition Dose of Ultrafine Particles from Improved Wood Stoves and Open Fireplaces

Ultrafine particles (UFPs; <100 nm) can penetrate deep into the respiratory tract, yet real-world estimates of inhaled and deposited UFP doses in homes with wood-burning appliances remain scarce. In this small, real-world exploratory study, particle number concentrations were measured at 1 min resolution for 11–12 winter days in each of four UK homes heated by an Ecodesign stove, a multifuel Ecodesign stove (two homes), or an open fireplace. The measurements were combined with age-, sex-, and activity-specific ventilation rates and the International Commission on Radiological Protection (ICRP) deposition model to estimate body-mass-normalised daily inhaled doses and absolute respiratory deposition dose (RDD) rates for modelled adult, young adult, and child scenarios. The mean daily inhaled doses ranged from 0.45 × 109 to 16.0 × 109 particles kg−1 day−1 during sitting and from 2.37 × 109 to 73.2 × 109 particles kg−1 day−1 during moderate activity, which increased the dose 4.5–5.3-fold for each home and scenario. Child scenarios had the highest body-mass-normalised inhaled doses (2.7–3.8 times those of adults), whereas adult males had the highest absolute RDD (mean 4.69 × 108 particles min−1). The mean household RDD ranged from 1.50 × 108 to 5.99 × 108 particles min−1. These results demonstrate substantial variability in the modelled UFP dose across household, demographic, and activity scenarios; however, because the four homes differed simultaneously in appliance type, fuel use, room characteristics, ventilation, and occupant behaviour, between-home differences were interpreted as exploratory associations rather than independent stove- or fuel-specific effects.