Question raised in Rajya Sabha on Contribution of diesel vehicles to air pollution of Delhi, 21/12/2015. Air pollution depends on prevailing meteorological conditions including wind direction, wind speed, mixing height, temperature variation, etc. The high level of air pollution in Delhi is mainly because of particulate matter (PM), while sulphur dioxide (SO2), benzene and ozone are within the limits during the month of November, 2015 (24 hourly averages). Oxides of Nitrogen (NOx) is showing mixed trends. The prominent sources of Particulate Matter (PM) emissions in Delhi include road dust re-suspension, vehicular exhaust emissions, air traffic, railways, construction activities, gensets, biomass and municipal solid waste burning, industrial emissions including from power plants.