Distribution Of NO2 Concentrations Research Articles

Analysis of NO2 gas concentration from the transportation sector through direct measurement and the Caline 4 dispersion program on the Makassar City Toll Road

Makassar as a developing city is experiencing development from the transportation sector. This resulted in the increasing number of vehicles. The increase in the number of vehicles produces emissions that cause air pollution, including NO2 emissions from motor vehicles. Currently NO2 concentration can be determined by direct measurement using the Gries Saltman method and pollutant prediction using the Caline program. This research was conducted on the Makassar city toll road which is divided into nine sample points. This study aims to determine the level of NO2 concentration from the transportation sector on the Makassar city toll road. Concentration results from direct measurements and predictions of caline are compared to show the level of concentration present. The results of the NO2 concentration are still below the threshold value that has been set in the latest applicable regulations, which is 200 g/Nm3 with a measurement time of 1 hour. The high or low value of NO2 concentration is influenced by the vehicle volume factor, where the NO2 concentration increases along with the increase in vehicle volume. In addition, it is also influenced by meteorological factors. Based on the results of the Caline-4 software output, the results obtained from the distribution of NO2 concentrations at each receptor found on the Toll Road in Makassar City, it can be stated that it is still below the threshold value set in the latest applicable regulations, which is 200 g/Nm3 with time measurement for one hour.

Distribution of NO2 Concentration during a Zonal Traveling Anticyclone in Nagoya City, Central Japan

Distribution of NO2 Concentration during a Zonal Traveling Anticyclone in Nagoya City, Central Japan

Monitoring of nitrogen dioxide in and around an Oman liquid natural gas plant using passive diffusion tubes: exposure and ISCST model study

Recognising that nitrogen dioxide (NO2) may be the primary air contaminant released from an Oman liquid natural gas (LNG) plant, this study has been designed with emphasis on this pollutant. The dispersion of NO2 was examined and compared with measured data during the period from 23 February to 1 April 2001. The observed concentrations were obtained by using NO2 diffusion tubes to monitor the spatial distribution of NO2 concentrations around at four sites downwind of the plant site. The Industrial Source Complex Short-Term (ISCST) dispersion model was used to predict concentrations at the same sites and for the same time period. Evaluation of the results showed that the model predicted concentrations lower than those observed. However, the comparisons showed that the relationship between the modelled and measured concentrations was consistent. The model also allows the detailed description of predicted concentrations in contour map form. Generally, the predicted concentrations were found to be lower than the permissible limit values, with the maximum ground-level concentrations being found much closer to the plant. On the basis of this study, it can be stated that the Oman LNG plant would not cause any significant deterioration in air quality.

Ground based observations of stratospheric nitrogen dioxide

Ground based measurements of stratospheric NO2, using four different established methods based on twilight sky observations in the spectral region 437.0–451.0 nm have been made at two locations: Primrose Lake (54.78°N, 110.05°W) and at Priddis (50.86°N, 114.29°W), Alberta, Canada, during March and April 1979. The four methods differ from one another on the basis of: (a) whether or not stratospheric ozone is taken into account, (b) whether a continuous NO2 absorption spectrum or just the absorption at a few discrete wavelengths is used for analysis, and (c) the assumed altitude distribution of NO2 concentration. Two different independently developed altitude distribution models are employed in obtaining the NO2 vertical column abundance and its effective altitude from a set of slant column abundances, measured in the twilight sky at different solar zenith angles in the range 85–96°. A comparison shows that the use of one or the other of these two models alone could introduce a difference of as much as 30% in the derived vertical column abundance.