:focal(800x602:801x603)/https://tf-cmsv2-smithsonianmag-media.s3.amazonaws.com/filer_public/1b/81/1b812dc0-f7a5-481f-8b41-30537983b09c/main_web.jpg)
In November 2016 the “Great Smog of Delhi” engulfed India’s capital and marked the city’s worst air quality event in 17 years. Fine particulate matter air pollution, or tiny particles measuring less than 2.5 micrometers in diameter—30 times thinner than a human hair—reached levels over 16 times the safe limit. The particles are small enough to be breathed deeply into lungs but not exhaled, so they can instead deposit and accumulate inside the body. Heavy smog was visible throughout the city, and hospital admissions of people with respiratory diseases spiked. Schools were closed, traffic was restricted, and construction and agricultural burning were halted.
About a month later, a team of environmental scientists and an artist arrived in Delhi to collaborate on an air pollution monitoring project. At that time the city was still experiencing an extremely poor air quality event—experts said just walking around the city at that time was equivalent to smoking over two packs of cigarettes a day—yet the smog was no longer as visible. Although the city was still deep in an air quality event, it had disappeared from the news cycle, says artist Robin Price, who was in Delhi at the time.
The collaboration between Price and environmental scientist Francis Pope of the University of Birmingham in England aimed to make the invisible threat of air pollution visible. They used digital “light painting,” a photography technique that captures moving light sources as “brushstrokes,” to illustrate where air pollutants were most concentrated. The project focused on three places that face different air pollution challenges: India, Ethiopia and the United Kingdom.
To create a light painting, Price set up a camera to capture a long-exposure photograph of an area, and then walked in front of the camera holding a low-cost air pollution sensor with LED lights. The sensor detected fine particulate matter air pollution, also known as PM2.5, and the LED lights flashed more where concentrations of PM2.5 were higher. The camera captured the light flashes as dots of light painting. The higher the PM2.5 concentration in an area, the more dots of light appear in the photograph. The project, called “Air of the Anthropocene,” has held photo exhibitions in Los Angeles; Belfast, Northern Ireland; and Birmingham, England, and has sparked global discussions about air pollution.
Pope and Price chose the locations for the photographs to represent day-to-day life: in playgrounds, kitchens and city streets. Air quality tends to be measured on a broad regional level and based on monitors at tops of buildings, but data at the local and street level can be useful, too, says Patrick Kinney, an environmental health researcher at Boston University. Local data about where pollution is coming from can help people avoid exposure to it, or it can lead them to avoid being a source themselves, says Kinney.
“Low-cost sensors, which have been a relatively recent technology that became available for air pollution use, have been particularly transformational,” says Pallavi Pant, head of global health at the nonprofit Health Effects Institute (HEI). Individuals can own these sensors, and so too can cities that can’t afford larger air pollution monitoring networks. The municipalities can use the data they gather to enact air pollution policies and monitor progress.
And in regions where literacy might not be widespread, images like the photos from this project can convey air pollution data in a more accessible way, says Price.
/https://tf-cmsv2-smithsonianmag-media.s3.amazonaws.com/filer_public/a3/2b/a32bbb0e-483e-4d62-8f7d-a6722080b383/1_playground-at-the-institute-of-himalayan-biotechnology-palampur-india-pm25-30-40-micrograms-per-cubic-metre.jpg)
“I can sit here and talk about numbers and data every day, I will lose people very quickly,” says Pant. “Something more interactive, more visual, but still bringing data and science at its core, is a very useful and interesting approach.”
The photos illustrate diverse air pollution issues among the three countries. In Wales, pollutant concentrations are high near the Port Talbot steelworks, which is the city’s main employer but also a major health hazard. Two playgrounds in India, one in urban Delhi and one in rural Palampur, show vastly different PM2.5 concentrations: The Delhi playground has about 12 times more PM2.5 pollution than the Palampur playground. Inside a kitchen with a wood stove in Ethiopia, PM2.5 concentrations are about 20 times greater than outside the home.
/https://tf-cmsv2-smithsonianmag-media.s3.amazonaws.com/filer_public/61/39/6139e8d3-2371-443c-bd27-97536f0cc073/2_web.jpg)
Air pollution is one of the world’s leading threats to human health, with polluted air causing about seven million premature deaths worldwide every year. New research from the HEI finds air pollution-related health problems have become the second leading risk factor for death worldwide, ranking below high blood pressure but now ranking above tobacco and poor diet.
Children under five years old are especially vulnerable to developing asthma and lung diseases due to poor air quality, according to the new HEI report. In 2021, air pollution exposure was linked to over 700,000 deaths of children under 5, the second-biggest risk factor for death worldwide for this age group after malnutrition. An estimated 500,000 of these deaths were linked to indoor air pollution from cooking with polluting fuels.
PM2.5 is the air pollutant most responsible for health issues. The tiny particles come from natural and anthropogenic sources, but the primary source of harmful levels of PM2.5 pollution is burning fossil fuels and biomass: for transportation, industry and in homes.
/https://tf-cmsv2-smithsonianmag-media.s3.amazonaws.com/filer_public/73/0d/730d5827-cfab-43d6-a5cc-1d27c6ad147a/3_web.jpg)
Over 90 percent of global air pollution deaths reported in the new HEI study are linked to PM2.5 air pollution. The particles are small enough to enter the lungs and bloodstream, increasing the risk of heart disease, stroke, diabetes, lung cancer and chronic obstructive pulmonary disease.
“[PM2.5] can be used as a very accurate predictor,” says Pant. “If you’re exposed to PM2.5, you’re going to experience health effects.”
Most countries focus on fighting air pollution by reducing emissions at the source, through vehicle or industrial regulation, for example, and through transitioning away from more polluting technologies. In India and Latin America, a major cause of PM2.5 pollution has been burning agricultural residue for cooking. So policy makers are focusing on creating alternatives: promoting agricultural waste recycling programs, for example, or promoting cooking with less polluting fuels.
Pant says we are seeing progress. Regions that face the highest levels of air pollution like Africa and Asia are now monitoring air quality more closely and implementing stricter air pollution policies. Since 2000, the air pollution-related death rate of children under 5 has dropped 53 percent, which the HEI report attributes mostly to improved access to clean fuel for cooking, improvements to health care and nutrition, and better awareness of the harmful effects of indoor air pollution.
Pope and Price are now trying to design their air pollution light-painting technique to be even more accessible, making the process open source to share with citizen scientists around the world who can create air quality light paintings themselves. Pope and Price are also working on an augmented reality approach to light painting using a phone app.
“With the availability of local information and local data, there has been greater public conversation around air pollution,” says Pant.
Pant also says understanding local-level air pollution is a powerful tool to change people’s attitudes, and to “create the environment where air pollution action and mitigation efforts are demanded, and well-received when they are implemented.”