Atmospheric aerosols at a regional background Himalayan site--Mukteshwar, India.

Continuous aerosol measurements were made at a regional background station (Mukteshwar) located in a rural Himalayan mountain terrain from December 2005 to December 2008 for a period of 3 years. The average concentrations of particulate matter less than or equal to 10 µm (PM10), particulate matter less than or equal to 2.5 µm (PM2.5) and black carbon (BC) are 46.0, 26.6 and 0.85 µg/m(3) during the study period. Majority of the PM10 values lie below 100 µg/m(3) while majority of the PM2.5 values lie below 30 µg/m(3). It is further seen that during the monsoon months, especially July and August, the average values are comparatively low. It is also noted that the PM2.5/PM10 ratios between 0.50 and 0.75 have the maximum frequency distribution in the data set. Furthermore, the monthly mean ratio of BC to PM2.5 mass lies between 3.0 and 7.5 % during the study period. Though the average PM10 and PM2.5 concentrations during the study period are less than the respective Indian ambient air quality standards, however, they are still above the WHO guidelines and would have adverse health impacts. This shows that even in rural/background regions that are far away from major pollution sources or urban areas, the aerosol concentrations are significant and require long-term monitoring, source quantification and aerosol model simulations.

Urban air quality management using emission inventory estimates for three Indian cities: Faridabad, Lucknow and Pune.

Urban air quality is an issue of major concern across many cities and towns in India. In particular, high levels of particulate matter (both suspended particulate matter (SPM) and respirable suspended particulate matter (RSPM)) are responsible for non-compliance against air quality standards. This paper analyses the status of air quality in the 16 most polluted Indian cities identified for priority action by the Hon'ble Supreme Court of India. Each city has its own unique problems depending on the nature of activities being undertaken. Thus, three cities, Pune, Lucknow, and Faridabad, which represent a top-ten urban agglomerate (based on population), a predominantly residential city and an industrial town are chosen for detailed analyses of the air quality problem. The causal factors for poor air quality are determined and sectoral emission loads are estimated for each city adopting a uniform approach that facilitates comparative evaluation. These provide an estimate of the major contributors to air pollution with specific reference to particulate matter, which is a major pollutant of concern. For each of these cities, an air quality management plan is suggested that specifically accounts for the contributing factors in each city. Further, quantitative estimates of the likely improvements due to implementation of some of the specific measures are also provided. An overall comparative assessment of the air quality issues across different cities can provide useful insights in the development of the management plan for the remaining cities as well.

Cost-effective control of SO2 emissions in Asia.

Despite recent efforts to limit the growth of SO(2) emissions in Asia, the negative environmental effects of sulphur emissions are likely to further increase in the future. This paper presents an extension of the RAINS-Asia integrated assessment model for acidification in Asia with an optimisation routine that can be used to identify cost-effective emission control strategies that achieve environmental targets for ambient SO(2) concentrations and sulphur deposition at least costs. Example scenarios developed with this optimisation module demonstrate a potential for significant cost savings in Asia, if emission controls are allocated to those sources that have the largest environmental impact and are cheapest to control. It is shown that strategies that simultaneously address harmful population exposure and the risk of vegetation damage from acid deposition result in the most cost-effective use of resources spent for emission controls.

Atmospheric dispersion of inflammable substances for estimating vulnerable zones in hydrocarbon industry.

The present study utilizes an operational model as well as simple empirical relationships for estimating hazard zones due to fire, explosion, and toxic vapor cloud dispersion. The empirical relationships are based on giving appropriate weightage to each of the parameters on which the hazard in question (viz, fire, explosion, toxic vapour dispersion) is dependent. Results from these two approaches [i.e., an operational model FLAMCALC of U.K. Health and Safety Executive (HSE) and an empirical model named FIREX] have been compared with the data obtained from the Mexico City disaster in 1984. In general, results from the empirical approach and FLAMCALC are comparable to the observed effects.

Estimation of vulnerable zones due to accidental release of toxic materials resulting in dense gas clouds.

Heavy gas dispersion models have been developed at IIT (hereinafter referred as IIT heavy gas models I and II) with a view to estimate vulnerable zones due to accidental (both instantaneous and continuous, respectively) release of dense toxic material in the atmosphere. The results obtained from IIT heavy gas models have been compared with those obtained from the DEGADIS model [Dense Gas Dispersion Model, developed by Havens and Spicer (1985) for the U.S. Coast Guard] as well as with the observed data collected during the Burro Series, Maplin Sands, and Thorney Island field trials. Both of these models include relevant features of dense gas dispersion, viz., gravity slumping, air entrainment, cloud heating, and transition to the passive phase, etc. The DEGADIS model has been considered for comparing the performance of IIT heavy gas models in this study because it incorporates most of the physical processes of dense gas dispersion in an elaborate manner, and has also been satisfactorily tested against field observations. The predictions from IIT heavy gas models indicate a fairly similar trend to the observed values from Thorney Island, Burro Series, and Maplin experiments with a tendency toward overprediction. There is a good agreement between the prediction of IIT Heavy Gas models I and II with those from DEGADIS, except for the simulations of IIT heavy gas model-I pertaining to very large release quantities under highly stable atmospheric conditions. In summary, the performance of IIT heavy gas models have been found to be reasonably good both with respect to the limited field data available and various simulations (selected on the basis of relevant storages in the industries and prevalent meteorological conditions performed with DEGADIS). However, there is a scope of improvement in the IIT heavy gas models (viz., better formulation for entrainment, modification of coefficients, transition criteria, etc.). Further, isotons (nomograms) have been prepared by using IIT heavy gas models for chlorine, which provide safe distance for various storage amounts for 24 meteorological scenarios prevalent in the entire year. These nomograms are prepared such that a nonspecialist can use them easily for control and management in case of an emergency requiring the evacuation of people in the affected region. These results can also be useful for siting and limiting the storage quantities.