fig3

Figure 3. Daily exposure dose by transportation mode across subgroups. (A) Walking; (B) public transportation; (C) car transportation; and (D) open transportation. Family annual income and expenditure are presented in units of 10,000 CNY. STP: Scientific and technical personnel; SEP: social and economic personnel; ORP: officers and related personnel; BSP: business and services personnel; FFP: agricultural personnel; MAP: manufacturing personnel; ICP: inconvenient-to-classify personnel.