苏拉特的空气质量

Is Surat polluted?

Surat is the eighth largest city in India and is situated in the state of Gujarat on the Tapti River, close to the Arabian Sea and was once a busy seaport. It is considered to be a busy trade centre with an extensive rail connection network. In 2011 the population was over 6 million but that will increase rapidly as it is predicted that Surat will be the world’s fastest growing city from 2019 to 2035. It has been selected to be developed as a “smart” city along with twenty others. It currently holds the title of India’s second cleanest city, in August 2020.

Meteorological conditions greatly affect the state of pollution. During conditions of very high wind speeds or heavy rainfall, emission produced by the city are soon carried away and, as such, do not have a real impact on the air pollution in Surat. Conversely, during the winter months when inversion rates and temperatures are low, there is a greater level of air pollution. Lower temperatures mean that homes need to be heated which adds to the city’s emissions.

What is the air quality index of Surat?

The AQI (Air Quality Index) recorded levels of air quality which are classed as “Unhealthy” and “Unhealthy for Sensitive groups” according to the recommended levels from the World Health Organisation (WHO). The main pollutant being PM2.5 with readings of 54.2 µg/m³. There are surprisingly no ground monitoring stations in Surat so these figures are based on satellite readings. However, emission inventory does take place. A “grid” is created over the city area and divided into areas of one square kilometre. These air pollutants in these segments are then measured and the results correlated centrally. The main pollutants measured are PM2.5, PM10, sulphur dioxide (SO₂), nitrogen oxides (NOx), carbon monoxide (CO) and volatile organic compounds (VOC)s.

With figures such as these, Surat’s residents run the risk of serious health problems related to the body’s respiratory system. This is mainly due to the high levels of PM2.5 and PM10 produced by industrial emissions are vehicular exhaust fumes.

What are the main sources of pollution in Surat?

An inventory of emissions was carried out in 2015 for the following pollutants: sulphur dioxide (SO₂), nitrogen oxides (NO_x), carbon dioxide (CO₂) and non-methane volatile organic compounds (NMVOCs). Particulate matter (PM) was classified into four types PM2.5, PM10, black carbon (BC) and organic carbon (OC). 2015 was classed as the “base “year and projections up to 2030 based on the readings were made. They were however revised in 2018.

These pollutants are caused through transportation, residential emissions such as cooking and heating, industrial emissions from small, medium and heavy industries, including the generation of power, dust created by the construction industry, the burning of agricultural organic waste, emission from diesel generators and emissions produced from the manufacture of bricks.

Textile mills in the Pandesara region produce Particulate Matter measuring, on average 184 µg/m³. The national average is 100 µg/m³. Sachin is another area where a concentration of textile mills can be found, here the PM reading is 188 µg/m³, Garden Silk Mills follow closely with readings of 184 µg/m³ and Delhi Gate with 164 µg/m³.

Can the quality of Surat’s air be improved?

Gujarat Pollution Control Board’s (GPCB) announced that their 2017-2018 figures for PM10 data show that levels of this pollutant were 10 times higher than acceptable levels. To combat this, they have made it mandatory for all textile producers to monitor and record their emissions. These figures are shared with the Gujarat Pollution Control Board who issue warnings against the offending mills. If the offences continue, the mills are asked to relocate to areas outside the city limits.

Many residents who live near the textile producers complain of suffering from breathing problems such as shortage of breath, an increase in acute asthma attacks and lung diseases which are a direct result of breathing in polluted air.

What are the health implications through Surat’s polluted air?

The worst type of pollutant, which is most hazardous to health, is the microscopic particles known as PM2.5. This notation indicates that the size of the particulate is less than 2.5 microns in diameter or 30 times smaller than the width of a strand of human hair. At such a small size, they have the ability to bypass the body’s defence mechanism and become deeply lodged at the base of the bronchial tubes, in the alveoli. There are approximately 480 million of these tiny air sacs that expand to take in the oxygen when the body breathes in and contract to expel the carbon dioxide when the body breathes out, known as ventilation. This exchange of oxygen and carbon dioxide is known as diffusion. As blood moves through the capillaries or blood vessels in the alveoli walls, oxygen is collected and carbon dioxide is deposited. This process is known as perfusion. If these cells become contaminated by PM2.5 particulates their efficiency will be compromised. As blood passes through their walls, it is possible for the contaminants to pass through to the blood. Here they are carried around the body and can eventually end up in the heart.

Lung diseases can take many forms such as chronic obstructive pulmonary disease (COPD) which is the obstruction of the airways caused by damaged alveoli walls. Damage to their walls causes them to break down thus reducing their capacity to exchange oxygen for carbon dioxide.

Idiopathic pulmonary fibrosis is caused by the alveoli walls becoming thickened and scarred due to the presence of pollutants. Cancers can grow inside the damaged cells which can also fill up with fluids and cause pneumonia.

Extra care must be taken by the groups of people who are more susceptible to polluted air. These include people with known existing medical conditions, pregnant women, senior citizens, children under the age of 14 years, outdoor workers and athletes who partake in vigorous outdoor exercise.

People from these vulnerable groups are advised to stay inside when the air quality is particularly bad. If going outside is unavoidable, the advice is to wear a good quality mask and to limit the time spent outside to as short as possible.