Adjusted PbA-PbB relationship. The figure was generated from the linear mixed-effects model adjusted for age, sex, job department, year of PbB measurement, tenure at time of measurement, and seasonality of measurement. The dots represent PbA-PbB measurement pairs (n = 2221), with those in each unique shade representing repeated measurements from a unique worker (total n = 236 workers). The darker and narrower band represents the 95% confidence band, conditioning on male sex, an age of 31.85 years, job tenure of 3.85 years, and in the COS department in the spring of 2018. The lighter and wider band represents the 95% prediction band for any male worker who is 31.85 years old, has a job tenure of 3.85 years, and works in the COS department in the spring of 2018, considering only the variation in the fixed effect of PbA. COS, Cast on Strap; PbA, concentration of lead in air; PbB, concentration of lead in blood.