Reducing air pollution : Impact and prevention

Debapriya Mukherjee
The pollution level in the city of Delhi has reached to alarming proportion over the years and winter haze is a regular visitor in northern India. In an effort to clear the hazy skies, the government declared a public health emergency, restricting car use, shutting primary schools and halting construction projects. These measures could not solve the acute air quality crisis though it certainly reduced peak pollution loads but not capable to create much impact in the long term. However, these actions create awareness among the middle class which had so far been unconcerned.  People have realized that severity of air pollution problem is increasing faster than government is responding to this problem. This problem has become a severe threat for human health in the past several years in India. In many areas over the weekend, levels of deadly particulate matter reached around 60 times the global safety threshold, or the equivalent of smoking more than two packs of cigarettes a day. People huddled around air purifiers, sealed door cracks with towels and prayed for rain.
The major cause of acute air pollution crisis in Delhi is attributed to its geographical location. Delhi is practically a land-locked megacity with limited avenues for the ?ushing of polluted air out of the city, or its replacement with air from relatively unpolluted marine regions.  These critical features are common in many growing non-coastal megacities. The problem of very poor flushing out is further aggravated on account of unplanned urbanization with massive development of housing and commercial space within the core of these cities without optimizing urban function and spatial lay out.  During the winter, cold air often moves down the Himalaya Mountains, settling over northern India’s Ganges Plain. This layer of cold air gets trapped beneath a layer of warmer air. Since the cold air cannot rise above the warm air, pollution builds in the cold air as long as the temperature inversion lasts. In contrast, those megacities which are located close to coastlines bene?t from sea breezes that can exchange maritime and urban air on a diurnal cycle.
About 65 per cent of pollution is clearly attributed to rapid economic growth  that has resulted in an increase in motor vehicle; unplanned urbanization and industrial and agricultural activities leading to serious air quality issues across India including Delhi.  During November, smoke from upwind agricultural burning combines with Delhi’s year-round urban pollution — a toxic mix of vehicle exhaust, industrial emissions, garbage burning in open and in landfills and construction dust — caused an eye-watering smog. Fireworks from Diwali celebrations   further aggravated the city’s air pollution crisis. Thereby simply stopping of agricultural burning cannot solve this problem. 
One of the most dangerous components of air pollution is fine particulate matter.  This fine pollution mainly comes from burning things: Coal in power plants, gasoline in cars, chemicals in industrial processes, or woody materials and whatever else ignites during wildfires. The particles are too small for the eye to see — each about 35 times smaller than a grain of fine beach sand — but in high concentrations they cast a haze in the sky. Upon breathing in, they wreak havoc on human health.  These particles can penetrate deeply into the lungs causing serious health complications. Also gaseous substances present in the air further aggravated the health problem.
The impact of particulate matter on human health has been highlighted elaborately but the effects of that fine particulates on plants remain neglected. Tiny pores in the leaves, the stomata, are the gatekeepers that regulate how much water vapor is released to the atmosphere. Stomata also allow carbon dioxide for photosynthetic production of energy storing sugars. This causes a dilemma for plants, between thirst and starvation: Either closing the stomata saves water but restricts the uptake of carbon dioxide or opening the pores allow carbon dioxide to enter, but at the cost of increased water loss. Plants have adapted stomatal regulation to prevailing ambient conditions over evolutionary timescales, but particulate matter concentrations with toxic compounds were generally much lower than they are today as advocated by the researchers. Damage of the plants on account of this air pollution will cause deterioration of urban ecosystem leading to further adverse impact on environment and human heath.
The regulatory agencies have stipulated a series of actions for almost all sectors to control air pollution over the past decade. These actions include relocation of polluting industries, introduction of improved emission norms for vehicles, phasing out of lead from gasoline, reduction of sulphur in diesel and benzene in gasoline, city public transport fleet on compressed natural gas (CNG) and banning of 15-year old commercial vehicles in many areas. Also the government implemented BSIV standards for vehicular technology and fuel, in Delhi and other metropolitan cities of India in 2010. Despite these initiatives, data generated over the years reveal that air pollution levels are still far above the permissible levels at many sites across India. Though regulatory authorities claim that series of actions taken by them helps to reduce pollution level in this year particularly in Delhi but in reality suffering of the people has reached to alarming proportions as air quality is deteriorating rapidly over the years.
Regulatory authorities frame the rules/regulations/ permissible levels and serving the notices to noncompliant organizations but without any sincere thought being given to their implementation. Our political rulers or governments both in center and states practically ignore the gulf between permissible standard stipulated by the regulatory authorities and controlling air pollution realities at source.
Regulatory pressure compelled these industries to adopt  end-of-pipe treatment technique to mitigate environmental pollution but non-compliance is a common feature due to failure of the pollution control system.  The regulatory agencies inspect the industries once or twice in a year but unable to ensure consistent control of pollution. It is not always feasible with limited trained/experienced personnel to continuously monitor the environmental performance over the time and thereby the environmental crisis and social problems remain unattended.   Reducing this pollution problem needs environmental improvement at the micro level, a goal which has been stubbornly elusive in India. Now it is necessary to create changes in industrial production, transportation system, agriculture activities, domestic consumption and solid waste management through adoption of  Cleaner production (CP) principles and practices that could support  economic and environmental bene?ts.   
The cost effective CP can only improve material utilization and reduce energy consumption and waste emission.  The proper knowledge /understanding  of these benefits among the owners’ of these sectors could help them to  invest in infrastructure, including clean technologies and environmental capacity, fostering CP implementation. In this context it is pertinent to mention that regulatory authorities both in central and states need enormous efforts to improve the standards on environmental protection, energy consumption, safety and quality,  promote cleaner production, build eco-industrial parks and constantly boost industrial restructuring and upgrading to reduce pollution level.  Most importantly CP concept must be pursued to reduce pollution intensity of  iron & steel, cement, chemical, petrochemical and other key industries with the increase of green coverage, water area, ecological and clean-type watersheds  in these industrial premises. Also city plans must be done based on an air shed approach with clear understanding of the topography and meteorology that impact level of pollutant concentrations, not simply cut-and-paste report by consultants based on spurious primary and secondary data. (To be contd)