印度的空气质量

How bad is India’s air pollution?

In 2019, as part of a worldwide survey, it was discovered that 21 out of the 30 most polluted cities were in India. And this pushed India’s ranking as a country to 5th place, according to figures published by iqair.com. The US AQI number averaged out at 152 and the PM2.5 figure recorded was 58.08µg/m³. This concentration was 5 times higher than that recommended by the World Health Organisation (WHO). This is an overall improvement on the 2018 figure of 72.54µg/m³. This means serious health problems for most of the country.

Over 50 over cent of this pollution comes from industry, followed by 27 per cent from vehicles, 17 per cent from crop burning and 7 per cent by domestic cooking. Over 2 million Indians lose their life to causes attributed to air pollution.

In the urban areas, most of the pollution comes from industry and vehicles, whereas in the rural areas, most comes from the burning of organic material. This material is used as a fuel for the domestic stoves, and also in the heaters needed to keep the houses warm in the colder months. During autumn and winter, huge amounts of stubble are burnt in the fields as a way of preparing the ground for the next crop. This method is much cheaper than the alternative option of ploughing the residue back into the land. This can be particularly bad as garbage is often thrown into the fires by way of disposal.

This combines with other pollutants to rank India as the world’s third greatest producer of greenhouse gases, behind China and the USA. The Air (Prevention and Control of Pollution) Act was inaugurated in the early ‘80s but has failed to make an impact due to the poor enforcement of the rules.

Official attitudes to the poor air quality is changing, especially since schools in Delhi had to close for several days in December 2017 due to the dangerous levels of pollutants present in the air. As more people are aware of the consequences of breathing poor quality air, the pressure is mounting on the authorities to do something about it.

What are the sources of India’s polluted air?

Fuel used for domestic stoves is usually made from a wet mixture of pieces of wood, dried leaves, hay and dried animal dung. This is fashioned into discs and dried in the sunshine. When it is burned in the stoves or chullas, it produces smoke and other pollutants five times higher than if coal were burnt. It is thought that in excess of 100 million households use these stoves up to 3 times a day, 7 days a week. Electricity or other clean fuels are not available in many remote areas. Even in cities where electricity is available, it is traditional to use these types of stove and 24 percent of city pollutants are attributed to such habits.

Some Indian auto-rickshaws and taxis run on fuel that has been adulterated by other, cheaper ingredients. This is a common occurrence in all of South Asia. The taxation system in India exacerbates this situation because gasoline carries a much higher rate of tax than diesel. This, in turn, carries a higher level than kerosene because kerosene is intended to be used as a cooking fuel. Other volatile liquids such as lubricants and solvents carry little or no tax and therefore make ideal ingredients to mix with the higher-priced fuels. To a low wage earner, this adulteration can save as much as 30 per cent over the period of one month.

Traffic congestion is a huge problem in India’s large cities and towns due to the number of cars trying to use what roads are available. Other factors include a lack of intra-city divided highways and traffic accidents due to the chaotic conditions on India’s roads due to the lackadaisical enforcement of the laws. Because of the bottle-necks created by junctions, traffic remains at a standstill with the engines idling. Monitoring stations near some of the large intersections record noticeably higher figures than those recorded elsewhere.

Dust produced from the demolition and subsequent building of new properties contributes to the poor quality of air in the city. During the dry season, dust is blown in from the desert-dry countryside and deposited in the city when the wind pressure drops as it travels over the buildings.

The air quality in the capital of Delhi always drops to the “severe” category during the winter months. Primarily, this is due to the practice of burning the stubble after the harvest to prepare for the planting of next season’s crop. It is reported that this alone is responsible for 32 per cent of Delhi’s PM2.5 particulate matter. At 292micrograms per cubic metre, the figure is 5 times higher than the World Health Organisation’s recommended safe limit. Weather conditions play an important part in the dispersal of airborne particles through both wind and rain.

Another major contributor to the air pollution was the Badarpur Thermal Power Station. This was built in 1973 and produced a mere 8 per cent of Delhi’s electricity yet was accountable for 80-90 per cent of the particulate matter. In November 2017 during “The Great Smog of Delhi” it was temporarily shut down to alleviate the smog but restarted the following February. However, due to the amount of pollution it created, it was shut down permanently in late 2018.

What effects does this poor air quality have on health?

The levels of the pollutant PM 2.5 are often well above the World Health Organisation’s recommended level of exposure (often over 5 times higher) and this leads to serious respiratory problem for those exposed to it. This is from both outside and household air pollution. Records show that in 2019 over 1.6 million deaths were attributed to poor air quality. The cause of death ranged from strokes, diabetes, lung cancer and myocardial infarctions. Also in this year, the State of Global Air 2020 noted that air pollution is now the largest risk factor for death amongst all other forms.

Household and outdoor particulate matter pollution was the main cause of death for more than 100,000 infants during the first month of their lives. A large percentage of these deaths were linked to the use of solid fuel biomass (charcoal, wood and dried dung cakes) used for cooking and heating homes.

In comparison to other countries, Indians are exposed to an average of 83.2 μg/cubic metre of PM2.5 pollutants compared to cleaner countries which record a relatively tiny figure of just 8μg / cubic metre.

Poor air quality has a drastic effect on the human respiratory system because the small PM 2.5 particulates travel deep into the lung tissue as far as the alveoli. From here they can pass through body tissue and can even enter the heart. Reduced lung capacity, sore throats, coughs, fatigue, lung cancer and headaches are all typical symptoms of exposure to polluted air.

A doctor from Delhi’s Sir Ganga Ram Hospital remarked that when he first started practising some 30 years ago, most of his patients suffering from lung cancer were male smokers in their 60s. But recently the doctor has reported that his patients now are usually non-smokers, and some 40 per cent are female. He also noticed that the patients are now a lot younger with around 10 per cent being in their 30s and 40s. Even in the lungs of teenage patients, black deposits can be found which would have been unthinkable 30 years ago. COPD or chronic obstructive pulmonary disease is now the second-largest cause of death behind heart disease.

It has been noted that the levels of PM2.5 particles are affected by the population density

Can India’s air quality be improved?

At the beginning of 2019 the Indian government inaugurated the National Clean Air Program (NCAP) to address the situation. It is their aim to reduce levels of air pollution by 20-30 per cent by 2024 in over 122 of the worst affected cities. Actions being taken in New Delhi, Ahmedabad and Pune include the implementation of health risk communications plans, the increase in the number of monitoring stations and better control of industrial emissions.

NCAP routinely monitors the four air pollutants of sulphur dioxide (SO2), oxides of nitrogen (both NO2 and NO), PM10 particulates and suspended particulate matter (SMP). These are to be monitored at 308 stations in 115 towns and cities over 25 states and 4 territories. Meteorological readings are also recorded such as wind speed and direction, relative humidity and temperature. Readings are taken on a regular basis for both particulate matter and for gaseous pollutants. These readings are taken twice a week and will generate 104 observations over a period of 1 year.

Several cities, including Solapur and Ahmedabad have seen a reduction in PM10 particulates over the last few years. This is thought to be due to the measures taken to reduce sulphur from diesel fuel and stronger enforcement by the local authorities.

Sulphur Dioxide levels are decreasing in residential areas of Delhi. Mumbai, Lucknow and Bophal in recent years. This has been attributed to the introduction of cleaner fuels and the increased availability and usage of Liquid Natural Gas (LNG). The latter being encouraged for use as an alternative to biomass in household cooking stoves and in auto-rickshaws.

The government in New Delhi introduced the “odd/even” rule in late 2017. This simply means that cars with a registration plate ending in an even number are excluded from the city centre on certain days of the week. The same rule applies to the odd numbers for different days.

India’s goals over the next few years to reduce air pollution include the introduction of over 1,000 electrically powered buses and the upgrading of engines using fossil fuels to meet the stringent BS6 standards. It is hoped that by 2023 25 per cent of all privately owned vehicles on Indian roads will be Electric Vehicles (EVs), and all power plants will be using renewable energy too. Any vehicle older than 15 years or that fall below the BS6 emission standards will be banned from city roads.

In rural areas, farmers are being encouraged to hire a machine which converts organic waste to fertilizer thus eliminating the need to burn the straw at the end of each harvest.

With the advent of new technology, it will be easier to send information to the public to warn them about certain changes in the air quality.

The reduction of carbon emissions is hoped to reduce CO2 gases by 20 per cent by 2030 and to reach zero by 2075.

One of the initiatives being considered is the creation of a 1,600 kilometre long and 5 metre wide “green” corridor from Gujarat to Delhi with the planting of 1.35 billion native trees over the next ten years in order to naturally clean the air.

Delhi is almost free from the use of kerosene as a fuel and almost 90 per cent of the residents now use LPG (NPG) for cooking. The remaining 10 per cent still rely on the traditional fuels of wood, coal and dried animal dung.

By 2021, it is expected that the centre of Delhi will be solely powered by clean, sustainable energy

Where is the cleanest air in India?

The cleanest city in India is Satna in the state of Madhya Pradash with a 2019 PM2.5 reading of 15.5µg/m³ and a US AQI figure of 58. The next cleanest city was Kumbhori in the state of Maharashtra with a figure of 20.3µg/m³. Compare these figures with the dirtiest air which is found in Ghaziabad in Uttar Pradesh with a reading of 115µg/m³ and a US AQI figure of 179 and the second dirtiest city of Delhi with a recorded figure of 100µg/m³.

In certain areas of India, air quality has been getting better since 2018, albeit very slightly. The number of days when the pollutants were above recommended levels for PM2.5 fell in 2019 by comparison.

The geography of Northern India and its proximity to the Himalayas means that it is very difficult for polluted air to escape. During the winter months when the strength of the wind is greatly reduced, the area can be thought of as a bowl with nowhere for the pollutants to escape.