<img srcset="https://ichef.bbci.co.uk/ace/ws/240/cpsprodpb/bc80/live/05b6d210-a1d8-11ef-bb35-5d21e680a10f.jpg.webp 240w, https://ichef.bbci.co.uk/ace/ws/320/cpsprodpb/bc80/live/05b6d210-a1d8-11ef-bb35-5d21e680a10f.jpg.webp 320w, https://ichef.bbci.co.uk/ace/ws/480/cpsprodpb/bc80/live/05b6d210-a1d8-11ef-bb35-5d21e680a10f.jpg.webp 480w, https://ichef.bbci.co.uk/ace/ws/624/cpsprodpb/bc80/live/05b6d210-a1d8-11ef-bb35-5d21e680a10f.jpg.webp 624w, https://ichef.bbci.co.uk/ace/ws/800/cpsprodpb/bc80/live/05b6d210-a1d8-11ef-bb35-5d21e680a10f.jpg.webp 800w" sizes="(min-width: 1008px) 760px, 100vw" alt="The silhouettes of two people stand behind a bridge in New Delhi, against a backdrop of smoke and fog.” width=”1024″ height=”576″ src=”https://www.bbc.com/korean/articles/aspect-ratio:1024 / 576″ class=”bbc-139onq”/>photo captionNew Delhi, India, was ranked the most polluted capital city in the world, according to a global report last yearArticle related information
- Reporter, Luis Barruzzo
- Reporter, BBC World Service
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3 hours ago
India’s capital, New Delhi, and nearby cities have been experiencing toxic substances floating in the air and limited visibility for the past few weeks. Air pollution reached 30 to 35 times the safety standard recommended by the World Health Organization (WHO).
NASA satellite images capture thick smog over northern India and Pakistan. Smog has been causing flight delays and cancellations in the region for weeks.
According to iQair, a Switzerland-based Air Quality Index (AQI) measurement company, New Delhi had the most air pollution among capital cities around the world in 2023. By country, India was rated as the third most polluted country after Bangladesh and Pakistan.
In India, air pollution surges every year from October to January, the winter season. These are caused by low temperatures, smoke, dust, slow winds, vehicle exhaust, and burning crop stubble.
It is true that the current situation in India is serious, but air pollution is not just India’s problem. According to WHO data, 99% of the world’s population is breathing low-quality air. Low- and middle-income countries are particularly exposed to polluted air.
The UN estimates that 7 million people die prematurely every year due to air pollution.
So how do we measure air pollution? And to what extent is it a threat to our health?
How do you measure it?
Air pollutants come from human activities that use fossil fuels, such as vehicles and cooking, and natural activities, such as dust storms, forest fires, and volcanoes.
According to the United Nations Environment Program (UNEP), air quality monitoring equipment detects specific pollutants through sensors. Depending on the equipment, some measure fine dust density with a laser, while others evaluate the energy reflected or emitted by the Earth using satellite images.
Air pollutants that affect the human body and the environment include PM2.5 (ultra-fine dust), PM10 (fine dust), ground-level ozone, nitrogen dioxide, and sulfur dioxide.
Among them, PM2.5 refers to particles less than 2.5 micrometers in size, and if these particles enter the bloodstream, they can cause various diseases.
The concentration of these five major air pollutants is expressed as the Air Quality Index (AQI).
The indications are numerical values ranging from 0 (perfect air) to 500 (immediate risk to public health).
The purpose of AQI is to tell how clean or polluted the air is. It also warns of potential health effects that may occur within hours or days of exposure to polluted air.
According to UNEP, the AQI is created by combining data from government agencies, crowdsourcing, and measurements obtained using satellites.
In 2021, UNEP and partner IQ Air created the first real-time air pollution exposure calculator using verified measurements from 6,475 observation devices in 117 countries.
This calculator first measures PM2.5 levels, the most dangerous air pollutant, and uses AI to calculate the number of people exposed to air pollution on an hourly basis.
The Air Quality Index (AQI) indicator measures the concentration of five major pollutants in the air.
The AQI scale, which ranges from 0 (perfect air) to 500 (immediate risk to public health), indicates how clean or polluted the air is and describes potential health effects that may be felt within hours or days of exposure.
“AQI is a communication tool that protects public health by condensing complex air quality data into actionable information,” IQ Air spokesperson Armen Araradian told the BBC.
According to the United Nations Environment Program (UNEP), the Air Quality Database accurately combines data collected from government, public sources and satellite monitors to provide AQI figures. Data is weighted based on ‘reliability and type of pollution measured,’ the UN agency explained.
In 2021, UNEP and IQair launched the first real-time air pollution exposure calculator combining verified data from 6,475 monitors in 117 countries. This database first measures levels of PM2.5, the most dangerous air pollutant, and uses artificial intelligence (AI) to calculate population exposure to air pollution every hour.
“Globally, PM2.5 is often the primary pollutant driving the AQI, but this is not always the case,” said IQ Air’s Araradian. “As PM2.5 levels increase, vulnerable populations such as the elderly, children, and those with respiratory and cardiovascular diseases “This will be affected first,” he said.
“If levels continue to rise, the wider population is at risk of health impacts and the risk of more serious health outcomes increases in vulnerable groups.”
Araradian added that AQI levels in a particular city are not necessarily representative of the air quality in the region as a whole.
“Because the air quality index is based on data measured at specific monitoring stations, it may not capture significant local differences in air quality, particularly along busy roads or industrial areas,” he explained.
He added that establishing a “robust monitoring network” would be “most effective” to accurately determine air pollution levels in various areas across the city.
What levels of air pollution are harmful to humans?
Photo caption, Some trains were delayed or canceled due to thick smog at a train station in Amritsar, India on the 16th.
According to WHO guidelines, drinking air with an AQI below 100 does not cause any major problems. On the other hand, air in the 400 to 500 range is considered “severely” polluted.
IQ Air said that the AQI reached 500 in various parts of New Delhi on Wednesday morning. Satellite cities such as Noida and Gurgaon also recorded figures close to 500.
UNEP said in its 2021 report that 37% of countries around the world do not have legal requirements for air quality observations. Accordingly, experts are concerned that air quality observations are not conducted rigorously in many countries.
UNEP said, “Governments should legislate legal requirements for air quality observations and invest in infrastructure to improve the accuracy of data.”
What diseases are caused by air pollution?
image copyrightAFP
Photo caption: People commuting to work in thick smog in New Delhi, India
According to WHO, fine dust and other pollutants in the air can cause inflammation in the airways and lungs, damage the immune system, and reduce the blood’s oxygen-carrying capacity.
Exposure to these pollutants can cause respiratory infections, heart disease, stroke and lung cancer, especially in vulnerable populations such as children, the elderly and low-income people.
Among pollutants, ozone worsens asthma. Nitrogen dioxide and sulfur dioxide cause asthma and bronchial symptoms, lung inflammation, and decreased lung function.
WHO says poor air quality increases the risk of stillbirth, miscarriage, cognitive impairment and neurological diseases such as dementia.
Currently, the annual number of deaths worldwide due to air pollution is estimated to be 7 million. Of these, 4.2 million people died from outdoor pollution, and 3.8 million people died from indoor pollution, such as burning wood or charcoal.
According to WHO, about 85% of these deaths are linked to non-communicable diseases (NCDs), including heart disease, stroke, lung cancer, asthma, chronic obstructive pulmonary disease and diabetes. This is why air pollution is considered the second leading cause of NCDs worldwide, following tobacco.
The UN also notes that 90% of deaths due to outdoor air pollution occur in low- and middle-income countries.
According to a survey conducted in New Delhi and nearby cities by the online community platform ‘Local Circle’, in 81% of responding households, at least one member of the family experienced health problems due to pollution in the past three weeks.
Due to this situation, New Delhi authorities also created a ‘Response Action Plan’ banning all activities using coal and firewood and the use of diesel generators for non-emergency services. However, even this did not prevent the city’s air from being polluted to the extent that it was harmful to health.
Currently, city authorities are urging residents to avoid going outdoors as much as possible and to reduce exhaust gases by using public transportation when moving.
Where is air pollution the worst and where is the air quality the best?
According to IQ Air, as of 2023, Bangladesh, Pakistan, India, Tajikistan, Burkina Faso, Iraq, United Arab Emirates, Nepal, Egypt, and Democratic Republic of Congo were countries with severe air pollution.
On the other hand, the countries with clean air were French Polynesia, Mauritius, Iceland, Grenada, Bermuda, New Zealand, Australia, Estonia, Finland, and Sweden.
This ranking was based on the average annual PM2.5 concentration (μg/m³).
