Particle size: A missing factor in risk assessment of human exposure to toxic chemicals in settled indoor dust

► Selections of dust fractions in recent studies on toxic chemicals in settled indoor dust were various. ► Analytical results of toxic chemicals from different selections of dust fractions would vary up to 10-fold. ► Particle size is a significant influencing factor on risk assessment of human exposure to toxins in settled dust. ► A new methodology for risk assessment of human exposure to toxic chemicals in settled indoor dust is proposed.