NH3 NO NO2 Temperature Delhi (n = 192) NO -0.896*       NO2 0.975* -0.932*     Temperature 0.872* -0.772* 0.864*   RH -0.843* 0.774* -0.834* -0.995* Dibrugarh (n = 144) NO 0.093       NO2 0.054 0.478     Temperature 0.422 -0.117 -0.591*   RH -0.382 0.124 0.631* -0.995* Thiruvananthapuram (n = 168) NO 0.322       NO2 -0.307 -0.006     Temperature -0.254 0.277 0.578*   RH 0.313 -0.213 -0.618* -0.996* * Significant at 1% level.

Table 3: Correlation matrix of ambient trace gases and meteorological parameters.