Recent smoky wildfires are just part of a much larger, slow-burning global air pollution crisis.
By Sumi Mehta, Tom Matte, and Russell Dowling from the Vital Strategies Environmental Health Division.
Dramatic fire-related air pollution episodes have been prominently featured in the news over the past several months. For example, in the western United States, as the Thomas fire — California’s largest wildfire on record — burned, Santa Barbara County experienced the highest levels of health-damaging air pollution, measured using fine particles (PM2.5), recorded since measurements began in 1999.
While climate change has increased the severity and length of the fire season in recent years, wildfires naturally occur in many western US forests. But whether or not they are naturally occurring; wildfires, like fuel combustion in power plants and vehicles, cause air pollution that can result in serious illness and death.
A recent study in the United States estimated that fire-related increases in PM2.5 levels resulted in 1500–2500 deaths, and thousands of respiratory and cardiovascular hospital admissions, each year from 2008–2012.
The 2017 wildfire season was an especially severe one, amidst a trend of longer and more severe smoke events from fires that have been particularly jarring and newsworthy in western US cities, where decades of progress in air quality management has resulted in baseline air quality that is relatively good by global standards.
But these short-lived wildfire events are a small part of a much more serious, persistent, global air pollution problem. “Haze”, or visible air pollution, creates a shroud over Southeast Asia each year, that has been exacerbated in some seasons even in areas where there are no forests being burned.
Delhi earned the dubious distinction of being called the most polluted city on earth, with off-the chart peak air quality indices reported, and pollution measuring 10 times more than notoriously polluted Beijing on the same day and more than 20 times the level for which an air quality health advisory would be issued in the US. The Indian Medical Association declared a public health emergency, with prominent Delhi chest physicians and independent research groups noting that breathing the smoky air could be equated to smoking up to 50 cigarettes a day.
From the west coast of the United States, to Southeast Asia, to India, these ‘episodes’ have several things in common: they are not one-off incidents, but particularly troubling peaks within a series of annually recurring seasonal events. The fires represent recurring — and largely intentional — biomass burning whether for households cooking or heating or clearing of agricultural waste or forests. And in all cases, pollution from biomass fires is responsible for a staggering amount of illness and death each year.
Some of this burden comes from episodic, short-term increases in exposure to PM2.5 which are associated with increased risk of emergency room visits, hospitalizations, and premature death. In 2015, over 100,000 premature deaths were associated with fire-related haze over a 3-month period in Indonesia, Singapore, and Malaysia. Much of this global health burden, though, is caused by chronic, ongoing exposure, especially in regions where biomass fires are commonly used to meet household energy needs.
Household Biomass Fuel Burning and India’s Outdoor Air Pollution Crisis
Delhi’s pollution has become notorious, with the public outcry not surprisingly focused on the most visible source of pollution within the city: traffic. And yet, motor vehicles only account for a fraction of the pollution in the city.
In Delhi, and in India as a whole, the fires underlying the major source of pollution continue to burn in the kitchens of rural and peri-urban households across the country. 87% of rural households still rely on solid fuels, including wood, animal dung, and agricultural residues, as their main source of cooking. According to a recently published report, 24% of India’s outdoor air pollution can be attributed to household solid fuel emissions. In the densely populated states of Uttar Pradesh and Bihar, the household contribution to outdoor air pollution is even higher, at 30–50%.
As a result, of the 1.1M deaths from particulate matter air pollution in 2015 (over 10% of the total number of deaths in India), 75% of the air pollution-related deaths in India occur in rural areas. If you add these deaths to the number of deaths occurring in Indian households who still use wood, dung, agricultural residues, and coal as their main source of cooking and heating fuel, over 1.2 million deaths in India could be linked to household air pollution in 2015.
The Indian government’s Pradhan Mantri Ujjwala Yojana (PMUY) program is already demonstrating an active commitment to increasing access to one household energy solution, namely clean burning liquefied petroleum gas (LPG). PMUY has committed to providing LPG access to 80 million households by 2020. Beyond access, however, households will need to transition away from using traditional stoves and unprocessed fuels to using primarily clean fuels, including LPG, but also electric appliances and other clean technologies in order to achieve intended health benefits. Until this happens, rural India will continue to bear a disproportionate share of India’s air pollution exposure and its health effects.
Household Air Pollution: A Public Health Imperative
The household air pollution problem is not unique to India – 3 billion people around the world are exposed to household air pollution every day, resulting in 2.6 million deaths each year. Household air pollution is among the top global health risk factors. And yet, to date, the public health community has devoted inadequate attention and resources to the issue. In part because of this, global investments in expanding access to clean household energy lag far behind the need. The time has come to bring a public health approach to addressing the linked challenges of household and ambient air pollution.
We can’t clear the air without a targeted approach to accelerating the uptake and sustained use of clean household energy for the roughly 3 billion people living in households that continue to use solid fuels for cooking, heating, and lighting. Beyond theses households, we must work to put out all the fires causing smoke in our communities. Some of these may be within our households, others may be in our forests, and others may be further away (pollution doesn’t respect administrative boundaries). Comprehensive strategies to prevent air pollution related deaths will have to address all the leading sources of smoke in the community.