Figure 1. A portable particulate matter monitor hangs from Ritu’s pants pocket while she answers a text on the street near her work. She is engaged in her daily activities while the monitor collects regular measurements from the ambient air. (Photo: ICIMOD/Perrin Krisko)

Every day, Ritu Nath rides her bicycle 1.5 km from her apartment, which she rents with her three sisters, to her workplace, closer to the town centre in Dhangadhi. Every day, she glances at the rapidly rising alien structures in the fast-developing sub-metropolitan city home to 205,000 denizens. She cycles past the increasingly unfamiliar-looking central marketplace, with its bustle and stifling pollution. She cycles through the smoke billowing from the swarm of vehicles and the dust rising from the construction of the gargantuan road expansion project supported by the Asian Development Bank.

Amid Dhangadi’s scramble to develop into a modern city, Ritu is concerned about the environmental costs at which this may be achieved. Ritu wants Dhangadhi to move forward – but with caution.

She has flung herself at this thought. Ritu is part of a programme funded by the US Department of State and organised by Clean Energy Nepal which engages youth across the country on air pollution issues. Her project involves sewing reusable shopping bags and teaching schoolchildren about plastic upcycling. She also works with a number of community-based organisations to promote environmental stewardship.

Her daily bicycle ride ends at the city’s American Corner, part of a US initiative to cultivate spaces for learning and exposure to American culture, history, and current events. Ritu works as this American Corner’s Deputy Programme Coordinator, in charge of organising different engagement programmes. Here, she is also one of three volunteer citizen scientists working closely with me, monitoring air quality in Dhangadhi.

Air quality monitoring in Dhangadhi: The need for citizen science

Dhangadhi is the capital of Kailali District in far-western Nepal – a 670-km drive from Kathmandu. This hot and humid, fertile lowland lies atop the northern belt of India’s Uttar Pradesh. Rapid urbanisation and industrialisation, mass crop burning, and pollutants transported from across the border result in air pollution in the district. The flat terrain and proximity to the Himalayan range can also create a geographical condition where air pollution can get trapped.

Dhangadhi does not have publicly accessible air quality monitoring information. While a reference-grade air quality monitor exists, the resources required to maintain and share data from this device are unavailable. The nearest air quality monitor data comes from Mahendranagar, an approximately 60-km drive from Dhangadhi.

Air quality monitors offer some of the most reliable data about air quality on the ground. This data can inform daily decision-making, policy, and science. But air pollution is not stagnant – it evolves across time and space. That is why citizen scientists like Ritu are crucial in helping collect air quality data using low-cost, portable air monitors within their communities.

I thought air pollution wasn’t a huge problem here [Dhangadhi] … I thought air pollution was just in very urban places like Kathmandu. But these numbers show that we need precaution outside of Kathmandu too.
– Ritu Nath

Ritu’s daily air quality monitoring routine

Each morning at 7:30 AM, Ritu hooks one of the portable air monitors onto the pocket of her pants. The monitor weighs about 200 grams (around the same as a mid-sized apple) and hangs discreetly at her hip. While Ritu prepares breakfast using her liquefied petroleum gas (LPG) stove, the monitor collects 10-second measurements for PM1, PM2.5, PM10^[1], temperature, and relative humidity. The monitor uses an internal fan to draw ambient air into the device. A laser reflects light across the particles as they are sucked into the device, effectively detecting the quantity of particulate matter.

On this particular day, Ritu leaves her home around 8:00 AM. The monitor observes elevated levels of pollution in the morning before 10 AM. On her way to work, Ritu passes many diesel-powered vehicles, a scattering of small piles of burning waste on the side of the road, and clouds of suspended dust that hang in the air before the monsoon rains saturate the city’s streets. The weather is a sweltering 37 °C in April. Ritu escapes to her slightly cooler, fanned office, where she spends the majority of her time working.

Temperature and humidity affect air monitor readings. That is why Ritu’s monitor was collocated for 12 days with a reference-grade monitor before being launched into the field. Collocation allows the data analyst to derive a correction formula that can be applied to the air quality measurements Ritu collects around Dhangadhi.

When Ritu works inside, her monitor indicates that particulate matter levels taper off. In Ritu’s office building, airflow from outside is minimal, and insulation is optimal. She makes sure the monitor is not covered at any point. Ritu double-checks that her monitor is collecting measurements a couple of times throughout the day. She observes a small light that periodically flickers near its charging port. The monitor has a battery life of around 14 hours. She charges it every night, but sometimes the electricity fails, and she needs to plug it into a power bank during the day. That is not the case today – the monitor shows no signs of interruption.

At 1:30 PM, Ritu is ready for a snack. She walks a few blocks towards the tempting scent of samosas being cooked over an LPG stove – her monitor spikes to an unreadable level. Ritu can check her monitor’s uncorrected air quality readings every minute by opening an app on her smartphone, which connects to the monitor via Bluetooth. Sometimes, if she places her phone down in an out-of-range location with Bluetooth capability, the monitor saves 10-second measurements to its internal memory card instead. If that happens, Ritu must wait until the end of the day when she transfers her data from the monitoring device to her phone app to view the uncorrected data.

After 4:00 PM, the monitor’s readings do not subside. She hypothesises that at this time, people commute to their homes and start cooking. Ritu herself goes home to rest and cook with her sisters. She allows her monitor to run until 7:30 PM to complete 12 hours of data collection. She stops the monitor now by switching the ‘off’ button. It takes about 10 minutes for the more than 43,000 data points to be successfully transferred to the mobile app.

Now, Ritu scrolls on her app to visualise today’s data collection session and shares it via e-mail with me to correct and analyse. Based on a preliminary look, air quality did not meet World Health Organization (WHO)-recommended levels at any point during the day.

Ritu texts me: ‘I thought air pollution wasn’t a huge problem here … I thought air pollution was just in very urban places like Kathmandu. But these numbers show that we need precaution outside of Kathmandu too.’

I use the information that Ritu and other citizen scientists have collected to educate school administrators and other stakeholders in Dhangadhi about what sources of particulate matter individuals are exposed to and what can be done to reduce the health risks from air pollution.

About the author

Perrin Krisko, visiting scholar at ICIMOD and Fulbright researcher, uses low-cost air quality technologies to estimate hyperlocal particulate matter (PM2.5) and identify air pollution sources within Kailali District. Perrin teaches educators, like Ritu, in Kailali District how to track air quality throughout their daily routines using portable air monitors.

^[1] PM1 are ultrafine particulates with a diameter of fewer than 1 microns. PM2.5 have a diameter of less than 2.5 microns. PM10 means the particles have a diameter less than 10 microns, or 100 times smaller than a millimetre.

Perrin Krisko

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