From AQI To Particulate Matter: How Air Pollution Is Measured And Tracked

Pollution trackers, clubbed with air purifiers are the quintessential tools to healthy living in a modern Indian city. With pollution levels skyrocketing each year, trackers that assess the health of air quality in mega cities like Delhi and Mumbai are appearing more frequently.

Also Read: Delhi's AQI Turns Hazardous On The Morning After Diwali, Residents Gasp For Breath

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Most trackers work within the Air Quality Index (AQI), which is calculated by figuring out the average concentration of pollutants in air over a standard time interval - mostly 24 hours, but 8 hours for carbon monoxide and ozone.

The AQI takes into account PM 2.5 particles - that are 2.5 microns in width and about 30 times smaller than the diameter of a human hair, according to World Bank. It is also known as the "silent killer" as pollution takes hold in most major cities, killing about 1.66 million people in just 2019.

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While you read this article, the AQI in Delhi hit severe, mostly lingering above 400 - implying those healthy will be affected and ones with underlying health conditions may face extra discomfort. In India, the AQI was launched in 2015 to measure pollution levels. Think of a thermometer, but for the environment.

Evolution of pollution tracking technology

The technology to track hazardous pollutants was developed only recently, in the 1940s. The easiest way to measure pollution is to shine ultraviolet light through a tube containing outdoor air. Ozone absorbs UV light, which means that whatever amount passes through the tube reveals the concentration of pollutants at any given time.

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But now, satellites are used to measure the concentration of pollutants. For instance, in the US, NONOAA¡¯s GOES-R satellites track air pollution, with help from another satellite system called JPSS which can provide aerosol data of the entire planet once a day.

Also read: Save Your Breath & Ears: How Firecrackers Are Harmful For Your Health

Different methods are used to measure different kinds of pollutants in the air. According to Care4Air.org, the most common contemporary method is through a device called a diffusion tube. While most air pollutant devices suck in air, this tube doesn't employ the pump mechanism. Primarily used to absorb nitrogen dioxide, the method involves placing a plastic tube in the outdoors. The tube contains a metal gauze that absorbs the gas to measure its presence in the air.

To measure different concentrations of PM particles, the most common method is through a device called TEOM (Tapered Element Oscillating Microbalance) wherein a designated head (based on particles to be filtered) sucks in air. It can provide readings every 15 minutes. More on TEOM here.

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Also read: Explained: What Kind Of Firecrackers Are Banned In Indian Cities?

Delhi got its first giant smog tower in August 2021, which is equipped with 40 fans that use 5,000 filters to clean air. Touted as India's first large-scale air cleaning facility, the tower can clean 1,000 cubic metres of air each second and works for a kilometre of range.

What do you think about filtering measures currently in place? Is India doing doing enough to tackle air pollution? Let us know in the comments below. For more in the world of technology and science, keep reading Indiatimes.com.

Citation

World Bank Group. (2021, March 26). Understanding Air Pollution and the Way It Is Measured. World Bank.

Jeelani, G. (2021, November 3). Air pollution | How well do Delhi¡¯s giant smog towers combat bad air? Moneycontrol.

Statista. (2021b, October 4). Deaths due to air pollution in India 1990¨C2019.

Care4Air | Glossary. (n.d.). Care4Air.

Care4Air | Measuring Air Pollutants. (n.d.). Care4Air.