law: Air (Prevention and Control of Pollution) Act, 1981
  26. Power to take Samples of Air or Emission and Procedure to be followed in Connection Therewith.
  (1)
  
  A State Board or any officer empowered by it in this behalf shall have power to
  
  take, for the purpose of analysis, samples of air or emission from any chimney,
  
  flue or duct or any other outlet in such manner as may be prescribed.
  
  
  (2) The result of any analysis of a sample of emission taken under sub-section
  
  (1) shall be admissible in evidence in any legal proceeding unless the
  
  provisions of sub-sections (3) and (4) are complied with.
  (3)
  
  Subject to the provisions of sub-section (4), when a sample of emission is
  
  taken for analysis under sub-section (1), the person taking the sample shall -
  (a) serve on the occupier or his agent, a notice, then and
  
  there, in such form as may be prescribed, of his intention to have it so analyzed;
  (b) in the presence of the occupier or his agent, collect
  
  a sample of emission for analysis;
  (c) cause the sample to be placed in a container or
  
  containers which shall be marked and sealed and shall also be singed both by
  
  the person taking the sample and the occupier or his agent;
  (d) send, without delay, the container or containers to
  
  the laboratory established or recognized by the State Board under Section 17
  
  or, if a request in that behalf is made by the occupier or his agent when the
  
  notice is served on him under clause (a), to the laboratory established or
  
  specified under sub-section (1) of Section 28.
  (4)
  
  When a sample of emission is taken for analysis under sub-section (1) and the
  
  person taking the sample serves on the occupier or his agent, a notice under
  
  clause (a) of sub-section (3), then -
  (a) in a case where the occupier or his agent willfully
  
  absents himself, the person taking the sample shall collect the sample of
  
  emission for analysis to be placed in a container or containers which shall be
  
  marked and sealed and shall also be signed by the person taking the sample, and
  (b) in a case where the occupier or his agent is present
  
  at the time of taking the sample but refuses to sign the marked and sealed
  
  container or containers of the sample of emission as required under clause (c)
  
  of sub-section (3), the marked and sealed container or containers shall be
  
  signed by the person taking the sample, and the container or containers shall
  
  be sent without delay by the person taking the sample for analysis to the
  
  laboratory established or specified under sub-section 
  (1) of Section 28 and such person shall inform the
  
  Government analyst appointed under sub-section (1) of Section 29, in writing,
  
  about the willful absence of the occupier or his agent, or, as the case may be,
  
  his refusal to sign the container or containers.