Statistical Analysis of Air Quality Indices: A Study

Polluted air has adverse effects on entire nature and living beings. To communicate with the common man about ambient air quality, “Air Quality Index” may be defined as a single number for reporting the air quality with respect to its effects on the human health. Air quality indices (AQIs) for the years 2009 and 2010 are computed for one of the main cities of India viz. Chandigarh using US Environmental Protection Agency (USEPA) and Factor Analysis approaches. Four air pollutants viz. RSPM, SPM, NOx, and SO2 are considered for computation of AQIs in five different zones of Chandigarh as per the guidelines of Chandigarh pollution control committee (CPCC). The responsible pollutant in all the zones and overall responsible pollutant have been identified. Various data exploratory techniques applied to AQIs revealed that they follow positively skewed distributions. Further, Kolmogorav–Smirnove test and Q-Q plots suggest that log normal distribution fits well to AQIs of NOX and log-log normal distribution is reasonably adequate for AQIs of pollutants SPM and RSPM. With the help of these fitted models, some probabilities for the responsible pollutants to fall into good and harmful categories are calculated, thereby indicating the possible health hazards for the population.