The national capital New Delhi is once again choking under toxic winter smog. This is a regular winter feature as thick layers of toxic smog engulf Delhi. Several factors contribute to its poor air quality, including burning of crop residues in the neighbouring Punjab, Haryana and Uttar Pradesh, bursting of firecrackers during Diwali and overwhelming emissions from vehicles, among others.
To provide temporary relief after Diwali, the State government collaborated with IIT-Kanpur to conduct cloud seeding trials on October 28. They were vain efforts as they did not result in any significant rainfall.
Ironically, in 1998, Beijing was considered one of the most polluted cities in the world. Over a continuous period of 20 years (1998-2017), Beijing successfully reduced its pollution levels through a series of long-term air quality control programmes. The experience shows that similar long-term strategies can help New Delhi and other Indian cities achieve lasting improvements in air quality.
In the absence of a comprehensive, city-wide air-quality monitoring system, the precise annual AQI averages are not available as regards Beijing in 1998. However, the measurements that do exist from that period show annual averages of SO₂ at 90-120 µg/m³, NO₂ at 70-74 µg/m³, and PM10 exceeding 150-200 µg/m³ -- all of which represent seriously unhealthy levels. During winter, coal-based heating pushed pollution even higher, with many studies estimating that peak daily AQI values frequently surpassed 300-500(Hazardous) on the most polluted days.
In response to the alarming deterioration of air quality, Beijing launched a comprehensive pollution control programme in 1998. Large-scale clean-air measures were undertaken in preparation for the 2008 Olympic Games. The "Beijing Clean Air Action Plan," initiated in 2013, marked a turning point. Between 2013 and 2017, Beijing made remarkable progress, and its annual average AQI decreased from 140-150 (Poor) in 2013 to 80-90 (Moderate) by 2017.
Between 1998 and 2017, the annual average concentrations of SO₂, NO₂ and PM10 in Beijing fell by 93.3 per cent, 37.8 per cent and 55.3 per cent, respectively, thanks to a relentless war "on pollution control".
Air quality can be classified according to IQAir standards: They include AQI Range: 0-50 good, 51-100 moderate, 101-150 unhealthy for sensitive groups, 151-200 unhealthy, 201-300 very unhealthy and 301-500+ hazardous.
If these values are low, the air quality has improved.
Lessons from Beijing-1. Strengthening policies continuously:
From 1998 to 2017, Beijing responded proactively to increasing urban size, population, energy consumption and vehicle usage by adopting legal, administrative, economic and technological measures to control pollution.
2. Building an effective air-quality management system: Over two decades, Beijing developed a comprehensive management framework supported by national and municipal laws, regulations and a strong monitoring structure, involving city and district governments.
3. Strong local emission and fuel standards: It introduced stricter local emission norms and improved fuel-quality standards specifically tailored for the city's requirements.
4. Advanced monitoring systems: The city developed an integrated air-quality monitoring network combining satellite data, remote sensing and ground stations apart from tracking major pollution sources.
5. Public awareness and participation: Public access to real-time air quality data and pollution-control updates encouraged citizen involvement.
6. Transition to cleaner energy: Coal-fired energy use in urban and suburban regions was gradually replaced with gas and other clean energy sources. These areas were transformed into "coal-free zones" by 2017.
7. Vehicle-emission control systems: By studying global best practices and adapting them locally, Beijing developed its own advanced vehicle-emission control system.
8. Economic growth alongside pollution reduction:
Despite rapid economic growth -- maintaining an annual GDP growth rate of over 6.5 per cent -- Beijing achieved significant air-quality improvements, thanks to a gradual decline in carbon dioxide emissions, sustainable development and creation of green jobs.
Strong political will, clear goals, well-designed environmental laws, long-term plans, and people's participation enabled Beijing to succeed in controlling air pollution.
According to the World Health Organisation (WHO), 99 per cent of the world's population breathes polluted air, and air pollution causes seven million premature deaths every year. PM2.5 -- particulate matter with a diameter of 2.5 micrometres or less -- poses the greatest health risk. This can increase the risk of stroke, heart disease, lung disorders and cancer.
Air pollutants arise from both human-made and natural sources, including burning fossil fuels, dust storms, wildfires and volcanic eruptions. With long-term planning, cleaner energy adoption and collective public participation, air pollution can be significantly reduced.
(The writer is Professor of Chemistry and Environmental Sciences in Hyderabad)