This study was carried out to analyze the variations of Benzene, Toluene, and para- Xylene (BTp-X) present in the urban air of Delhi. These pollutants can enter into the human body through various pathways like inhalation, oral and dermal exposure posing adverse effects on human health. Keeping in view of the above facts, six different locations of Delhi were selected for the study during summer and winter seasons (2016-2017). The concentrations of BTp-X on online continuous monitoring system were analyzed by chromatographic separation in the gaseous phase followed by their detection using a Photo Ionization Detector (PID). The concentrations of BTp-X were found maximum at a high traffic intersection area as 68.35±48.26 µg/m3 and 86.84±32.55 µg/m3 in summer and winter seasons respectively and minimum at a residential area as 4.34±2.48 µg/m3 and 15.42±9.8 µg/m3 in summer and winter seasons respectively. The average BTp-X concentrations of summer and winter seasons were found as 9.88, 20.68, 28.52, 49.75, 64.04, and 77.59 µg/m3 at residential, institutional, commercial, low traffic intersection, moderate traffic intersection and high traffic intersection areas respectively. Clearly, it has been found that the concentrations of these compounds were more on the traffic areas indicating that the vehicles are the major emission source. Hence, it may be concluded that the number of vehicles along with the high traffic congestion on the city streets and roads results in more accumulation of aromatic compounds and deteriorate the urban air quality.

Little is known about pollution in urban snow and how aerosol and gaseous air pollutants interact with the urban snowpack. Here we investigate interactions of exhaust pollution with snow at low ambient temperature using fresh snow in a temperature-controlled chamber. A gasoline-powered engine from a modern light duty vehicle generated the exhaust and was operated in homogeneous and stratified engine regimes. We determined that, within a timescale of 30 min, snow takes up from the exhaust a large mass of organic pollutants and aerosol particles, which were observed by electron microscopy, mass spectrometry and aerosol sizers. Specifically, the concentration of total organic carbon in the exposed snow increased from 0.948 ± 0.009 to 1.828 ± 0.001 mg/L (homogeneous engine regime) and from 0.275 ± 0.005 to 0.514 ± 0.008 mg/L (stratified engine regime). The concentrations of benzene, toluene and 13 out of 16 measured polycyclic aromatic hydrocarbons (PAHs), particularly naphthalene, benz[a]anthracene, chrysene and benzo[a]pyrene in snow increased upon exposure from near the detection limit to 0.529 ± 0.058, 1.840 ± 0.200, 0.176 ± 0.020, 0.020 ± 0.005, 0.025 ± 0.005 and 0.028 ± 0.005 ng/kg, respectively, for the homogeneous regime. After contact with snow, 50–400 nm particles were present with higher relative abundance compared to the smaller nanoparticles (<50 nm), for the homogeneous regime. The lowering of temperature from 25 ± 1 °C to (−8) – (−10) ± 1 °C decreased the median mode diameter of the exhaust aerosol particles from 69 nm to 57 nm (p < 0.1) and addition of snow to 51 nm (p < 0.1) for the stratified regime, but increased it from 20 nm to 27 nm (p < 0.1) for the homogeneous regime. Future studies should focus on cycling of exhaust-derived pollutants between the atmosphere and cryosphere. The role of the effects we discovered should be evaluated as part of assessment of pollutant loads and exposures in regions with a defined winter season.

Concentrations of the elements Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn were measured in the leaves and bark of Robinia pseudoacacia and the soil in which it grew, in the town of Oleśnica (SW Poland) and at a control site. We selected this town because emission from motor vehicles is practically the only source of air pollution, and it seemed interesting to evaluate its influence on soil and plants. The self-organizing feature map (SOFM) yielded distinct groups of soils and R. pseudoacacia leaves and bark, depending on traffic intensity. Only the map classifying bark samples identified an additional group of highly polluted sites along the main highway from Wrocław to Warszawa. The bark of R. pseudoacacia seems to be a better bioindicator of long-term cumulative traffic pollution in the investigated area, while leaves are good indicators of short-term seasonal accumulation trends. Once trained, SOFM could be used in the future to recognize types of pollution.

Vehicle exhaust emissions are a dominant feature of urban environments and are widely believed to have detrimental effects on plants. The effects of diesel exhaust emissions on 12 herbaceous species were studied with respect to growth, flower development, leaf senescence and leaf surface wax characteristics. A diesel generator was used to produce concentrations of nitrogen oxides (NOx) representative of urban conditions, in solardome chambers. Annual mean NOx concentrations ranged from 77 nl l-l to 98 nl l-1, with NO:NO2 ratios of 1.4-2.2, providing a good experimental simulation of polluted roadside environments. Pollutant exposure resulted in species-specific changes in growth and phenology, with a consistent trend for accelerated senescence and delayed flowering. Leaf surface characteristics were also affected; contact angle measurements indicated changes in surface wax structure following pollutant exposure. The study demonstrated clearly the potential for realistic levels of vehicle exhaust pollution to have direct adverse effects on urban vegetation. Fumigation experiments demonstrate adverse effects of exhaust emissions on urban vegetation.

Lead is a well-known pollutant with documented toxicity. Lead-containing weights used to balance motor vehicle wheels are regularly lost from vehicles and enter the environment. Lead weights deposited on roadways in the vicinity of Trenton, NJ were gathered and measured from February 2006 to January 2009. Measurements included loss of mass from specific weights exposed to traffic. Extrapolation of the results to the entire state suggests that approximately 12 tons per year of lead in the form of wheel weights are deposited on New Jersey roadways, and that approximately 40 kg of lead enters the environment in the form of small particles formed from the abrasion and grinding action of traffic on weights deposited on roadways. This quantity of small particles is much less than the approximately 60 tons per year of lead estimated by an earlier study to enter New Jersey in precipitation, some of which may result from the combustion of leaded aviation fuel. The quantity is also likely small compared with the fluxes of lead into the environment that still continue from leaded paint and with the residue of finely dispersed lead from historical uses of leaded gas in motor vehicles that remains in the environment. The quantity of lead released to the environment in the form of wheel weights appears likely to decline in the future because of legislation, voluntary phase-outs by manufacturers, and new trends in wheel technology

Nitrogen dioxide is an important gaseous air pollutant. It plays a major role in atmospheric chemistry, particularly in the formation of secondary air pollutants, and contributes to environmental acidification. A comprehensive assessment of NO2 levels in the atmosphere is required for developing effective strategies for control of air pollution and air quality improvement. Air pollution is a serious problem in all major cities of Pakistan and needs to be addressed to minimize detrimental effects on human health and urban vegetation. In this research, we focused on the monitoring of NO2 levels in the urban environment of Rawalpindi city. Because of the lack of expensive continuous sampling devices and to get a good spatial coverage of the NO2 concentrations in the study area, NO2 passive samplers were exposed at 42 different sites within the city limits of Rawalpindi from January to December, 2008. Samplers were exchanged every 10 days and the associated meteorological conditions like temperature, wind speed, rainfall and relative humidity were also monitored. The average NO2 concentration was found to be 27.46 ± 0.32 ppb. The highest values of NO2 were measured near to main roads and educational institutions due to intense flow of road vehicles. Moreover, the study showed that the values obtained for NO2 for all sampling points exceeded the annual limit value set by World Health Organization. So, this is very important to take different steps to control this before it becomes a serious hazard for people living in those areas.

Samples of airborne particulate matter (PM₂.₅) were collected at a site in Lahore, Pakistan from November 2005 to January 2006. A total of 129 samples were collected using an Andersen Reference Ambient Air Sampler 2.5-400 sampler and analyzed for major ions, trace metals, and organic and elemental carbon concentrations. The data set was then analyzed by positive matrix factorization (PMF) to identify the possible sources of the atmospheric PM collected in this urban area. Six factors reproduced the PM₂.₅ sample compositions with meaningful physical interpretation of the resolved factors. The sources included secondary PM, diesel emissions, biomass burning, coal combustion, two-stroke vehicle exhaust, and industrial sources. Diesel and two-stroke vehicles contributed about 36%, biomass burning about 15%, and coal combustion sources around 13% of the PM₂.₅ mass. Nearly two thirds of the PM₂.₅ mass is carbonaceous material. Secondary particles contributed about 30% of PM₂.₅ mass. The conditional probability function (CPF) was then used to help identify likely locations of the sources present in this area. CPF analysis point to the east and northeast, which are directions of urban and industrial areas located across the border near Amritsar, India as the most probable source for high PM₂.₅ concentration from diesel and two-stroke vehicles exhaust in Lahore. Analysis of those days within three different ranges of PM₂.₅ concentration shows that most of the measured high PM₂.₅ mass concentrations were driven by diesel and two-stroke vehicle emissions including the associated primary sulfate. The use of the potential source contribution function (PSCF) to find the source locations of regionally transported particles is inapplicable in situations when high PM₂.₅ concentrations are dominated by local sources and local meteorology.