The current study discourses the impact of variation in PM$_{2.5}$ concentration on the ambient air quality of Delhi. The 24-hourly PM$_{2.5}$ concentration dataset was obtained from air quality measurement site (Anand Vihar) of Delhi Pollution Control Committee (DPCC) for the duration of April 2015 to December 2018. The annual and seasonal variability in the trend of ambient PM$_{2.5}$ along with cumulative impact of meteorological parameters have been analyzed. The overall percentage increase in annual PM$_{2.5}$ concentration, compared to National Ambient Air Quality Standards (NAAQS) guidelines, is observed to be 286.09%. The maximum concentration of fine particulate matter was recorded to be 788.6 $\mu$g/m$^{3}$ during post-monsoon season and it was found to be associated with lower ambient temperature of 21.34${\circ}$C and wind speed of 0.33 m/sec. Further, PM$_{2.5}$ concentration was found to be correlated with CO (R= 0.6515) and NH$_{3}$ (R= 0.6396) indicating similar sources of emission. Further, backward trajectory analysis revealed contribution in PM$_{2.5}$ concentration from the states of Punjab and Haryana. The results indicated that particulate pollution is likely to occur in urban atmospheric environments with low temperatures and low wind speeds.

$\bf{Highlights}$

$\bullet$ PM$_{2.5}$/PM$_{10}$ ratio was observed to be highest in November, December and January, attributing aggravated levels of particle pollution to anthropogenic sources.

$\bullet$ Seasonal analysis of PM$_{2.5}$ concentration indicated that particulate pollution was severe during post monsoon and winter months.

$\bullet$ Carbon monoxide (R = 0.6515; $R^{2}$ = 0.4244) and Ammonia (R = 0.6396; $R^{2}$ = 0.4088) were found to be correlated with PM$_{2.5}$.