Air quality in Shillong

Is there badly polluted air in Shillong?

Shillong is a city located in the northeastern region of India, within the state of Meghalaya. Coming in as the 330^th most populous city within the country, Shillong also has its fair share of air pollution issues, coming from a multitude of sources. With a population size of some 143,000 people (as per a census conducted in 2011, and thus will likely have grown considerably since then, along with industry and infrastructure), there is bound to be higher levels of air pollution present, as is common throughout many growing cities in India, with the capital itself also being subject to some extreme levels of pollution.

In late August of 2021, Shillong presented with a US AQI reading of 53, placing it into the 'moderate' air pollution rating bracket. This is color-coded as yellow, for ease of reference and navigation when referring to the air quality maps, graphs and forecasts present on this page as well as throughout the IQAir website. This rating also requires a US AQI reading of anywhere between 51 to 100 to be classified as such and indicates a level of air quality that is not particularly bad by any means but may aggravate pre-existing conditions amongst vulnerable portions of the population, as well as causing mild irritation to exposed mucous membranes such as the eyes or nose of healthy individuals.

At the time in which this US AQI reading was taken, Shillong was also found to have a PM2.5 reading that was slightly over the World Health Organization's (WHO's) recommendation for a safe level of exposure. PM2.5 is one of the most hazardous pollutants that can be found in the air, both in Shillong and throughout the world, being any material that is 2.5 micrometers or less in diameter. PM2.5 is also counted amongst the pollutants that go into making up the US AQI calculation, along with its larger cousin, PM10, and a variety of other pollutants released from various combustion sources or industrial processes.

Other readings that were taken over the course of August and July of 2021 were ones that generally did not carry with them signs of heavy air pollution. Other figures include ones such as 33 and 37, along with lows of 10 and 9, indicating a very decent level of air cleanliness. These readings all fell within the 'good' air quality rating bracket, which requires a reading of anywhere between 0 to 50 to be classified as such, and is one of the most optimal US AQI rating brackets that can be reached. Whilst these months had far more optimal levels when looking at the US AQI readings, there were however many other months whereby the pollution levels increased significantly, with many months from years past also having far higher readings of pollution present. These will be discussed in further detail in the following questions at the end of the article.

What causes pollution and decreased air quality in Shillong?

Sources of air pollution present in Shillong are similar to many different cities throughout India. Industrial processes are responsible for releasing large amounts of smoke, haze and hazardous clouds of particulate matter, with industrial boilers often relying on fossil fuels such as coal, oil, natural gas and diesel to get their energy. Furthermore, certain areas of the city would see people still utilizing organic material such as wood, charcoal and animal dung for cooking and heating within homes, typically more present in lower-income areas due to the necessity of utilizing such materials instead of paying for electricity.

The combustion of such materials releases many pollutants into the air, in a similar effect to what a forest fire would do, although on a smaller scale. However, the combination of thousands of households simultaneously burning these materials can cause large amounts of soot, volatile organic compounds (VOCs) and other hazardous pollutants to be released into the air. Meteorological conditions can also cause the situation to become worse, with both hotter and colder months bringing with them their issues. Hotter months and higher concentrations cause larger amounts of ozone (O₃) to be formed, particularly on roads where there are many pollutants such as oxides of nitrogen (NOx) along with other gases and chemicals that can convert into ozone when subject to enough solar radiation.

Cooler months often bring with them larger consumption of electricity in homes and businesses, causing power plants to go through far more fuels and thus release greater quantities of pollution into the air. Furthermore, the aforementioned households that still use traditional methods of cooking or heating will often go through greater quantities of organic material, thus also causing larger amounts of pollution to be released. Other sources of pollution of note are fine particles that emanate from construction or demolition sites (particularly in poorly maintained construction sites), along with vehicle exhaust fumes and the burning of waste or refuse out in the open all contributing to heightened levels of air pollution.

What are the main health issues to deal with in Shillong?

Some health issues that one may experience when exposed to higher levels of air pollution in Shillong include coughs, irritation to the respiratory tract and chest pain or infections. Skin conditions and rashes may also present themselves or become worse due to pollution exposure, with acne, psoriasis and eczema being some of these conditions.

Other more serious health issues include ones such as ischemic heart disease, heart attacks, strokes, angina and arrhythmias, along with instances of premature death occurring as a direct result of excess pollution exposure.

When does Shillong have the worst level of air quality?

Observing the PM2.5 levels recorded over the course of 2020, it can be seen the city presented with its highest readings over January through to May, along with November and December also having further elevated figures. January through to May presented with PM2.5 readings of 31.3 μg/m³, 38.4 μg/m³, 34 μg/m³, 20.8 μg/m³ and 18 μg/m³ respectively, making February the most polluted month of the year by a significant amount, being the only PM2.5 reading to make its way into the 'unhealthy for sensitive groups' rating bracket, which requires a PM2.5 reading of anywhere between 35.5 to 55.4 μg/m³ to be classified as such.

Does Shillong have any months with cleaner air quality?

Despite many of the months coming in with ratings of 'moderate' air quality and higher, there were two months of the year in 2020 that stood out as having significantly better levels of air cleanliness present. These were July and August, which both presented with readings of 11.3 μg/m³ and 11.7 μg/m³, placing them within the 'good' air quality rating bracket, which requires a fine margin of entry at 10 to 12 μg/m³ for classification.