How to manage winter-induced aggravated air pollution levels
A considerable contribution to aggravated levels of pollution in the winters is due to inversion-triggered long periods of low ventilation and a consequent build-up of pollutants.
By Yashpal Singh Winters bring in aggravated levels of air pollution and a lot of concern for managing the same. Considerable work has been done by regulatory authorities like the Ministry of Environment, Forest and Climate Change, state governments, the central and state pollution control boards, and ground water authorities, coupled with a very proactive judiciary. There is certainly a perceptible improvement in air and water quality; but with little or no difference to the sources of pollution over the preceding months, winters do present a grave situation.
A considerable contribution to aggravated levels of pollution in the winters is due to inversion-triggered long periods of low ventilation and a consequent build-up of pollutants. Studies have indicated that Delhi witnesses poor ventilation characterised by stable inversion for about 12 hours (1800 to 0600 hours), and a good atmospheric ventilation period of only about seven hours (1000 to 1700 hours) during the day.
A better understanding of ventilation characteristics is very important for controlling air pollution—poor ventilation aggravates pollution.
If high emission peaks of the fuel burning and combustion cycles (fires, fuel burning, shutdowns, etc) are only allowed during periods of good ventilation, build-up is avoided, but the same processes of burning fuel during the periods of low ventilation in winter evenings will add to pollution by trapping the emissions within. Poor ventilation exists for only about two hours during the summers; it may extend to about four hours during the post-monsoon period and up to 12 hours in the winters. Information of good ventilation and poor ventilation periods could, therefore, be utilised to regulate the operating hours of emission sources. Stricter regulation during periods of poor ventilation may help.
I think Uttar Pradesh has tried it for the Taj Trapezium Zone Area when fuel burning was prohibited from 4.00 p.m. to 6.00 a.m. It did help. We could also utilise this concept in managing vehicular emissions through the odd-even concept, which could be applied only during the periods of poor ventilation. Periods of good ventilation could have relaxed traffic movements.
With a considerable part of pollution coming from natural/area sources also, especially dust, we may need to re-examine the ambient air quality standards that are currently difficult to achieve. Even with the best of control options, it is unlikely that a particulate matter standard of 100 microgram/m3 of PM10 and a standard of 60 microgram/m3 of PM 2.5 could be met. Under such circumstances, it could be advisable to reconsider the standards, based on the contribution of area sources and meteorological conditions; otherwise, we may have to freeze all further development that is likely to cause an increase in pollution beyond the prescribed standards.
The Environment Protection Rules, 1986, provide that the ambient air quality shall not be allowed to increase beyond the prescribed standards. The Central Pollution Control Board (CPCB) has evolved the air pollution index. It appears to be a better tool for assessing air quality as it takes into consideration the concentration of all the pollutants in a single representative index. This index could also be considered to be notified as a standard.
Source apportionment studies help us quantify the percentage contribution from various sources and carrying-capacity assessments help us in understanding how much of the pollutant can be assimilated into the system without adverse impacts. All frameworks and action plans for future development could be based on source apportionment studies and carrying-capacity assessments. This will help us focus on the main issues.
Crop stubble burning has been established to play a very significant role in the deterioration of air quality. There is an immediate need to regulate this. If stubble burning is inevitable, it could be allowed by permit only. The impacts during the winter months could be reduced by ensuring that no stubble is burnt between 1400 hours and 1000 hours during the months of September to February.
This could be examined as an agreed enforcement measure. To offset the high incidence of costs on farmers, sustainable stubble harvesting and disposal practices could be included as a recognised CSR activity, and the corporate sector motivated to participate by investing in capital expenditure towards setting up scaled-up sustainable stubble management centres.
Residual crops could be harvested and utilised in energy production, biogas generation, commercial feedstock for cattle, composting, and conversion in biochar, or as raw material.
Inadequate infrastructure support and burgeoning population pressures put a huge responsibility on the regulatory bodies who would like to ensure that all future development proposals are evaluated in terms of adequacy of supporting infrastructure and allowed only after the participating agencies have certified this adequacy. This would include power, water, roads, sewage treatment, MSW and other wastes, and ambient air quality. This is not being judiciously practised. At times, permissions for additional use of water are given by municipal authorities merely based on the adequacy of the storage and distribution infrastructure without assessing the availability of water or the impact on competing uses.
Unplanned activities such as conversion of residential to commercial land-use or arbitrary increases in FAR without assessing the carrying capacity have far-reaching environmental consequences and the quality of life of urban residents. Although mandated by law, many master plans may not still have environmental clearances. Solid waste management has, of course, to be stepped up, and segregation at source made more robust. Storage of desilted sludge on roads and embankments has to be prohibited. Staggered business timings, particularly restricting business hours during winter nights, may reduce the emission build-up during fumigation periods.
Apart from regulation, good governance and the will and character of all the stakeholders is extremely important in achieving the objectives of a clean environment. We have to develop conservation as a culture. Regulation may breed evasion. Culture will not.
The author is chairman, the Wealthy Waste School India, and former director, Environment, government of UP