To cite package ‘APTIcalc’ in publications use:

  Paul N, Singh R, Chavan S, Ponnaganti N, Reddy K (2025). _APTIcalc:
  Air Pollution Tolerance Index (APTI) Calculator_. R package version
  0.1.1, <https://CRAN.R-project.org/package=APTIcalc>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {APTIcalc: Air Pollution Tolerance Index (APTI) Calculator},
    author = {Nobin Chandra Paul and Rupali Singh and Sangram B Chavan and Navyasree Ponnaganti and K. Sammi Reddy},
    year = {2025},
    note = {R package version 0.1.1},
    url = {https://CRAN.R-project.org/package=APTIcalc},
  }