                              Indoor air, occupied, PM~00~                       Sampled onto PCTE filters                     0                     0                           0                                  0                                          Indoor air, occupied, PM~0.0~                       Sampled onto PCTE filters                     0                     0                           0                                 \_                                            Indoor air, vacant, PM~00~                        Sampled onto PCTE filters                     0                     0                           0                                 \_                                           Indoor air, vacant, PM~0