Air Quality Suffering in China

Residents of Beijing and many other cities in China were warned to stay inside in mid-January 2013 as the nation faced one of the worst periods of air quality in recent history. The Chinese government ordered factories to scale back emissions, while hospitals saw spikes of more than 20 to 30 percent in patients complaining of respiratory issues, according to news reports.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired these natural-color images of northeastern China on January 14 (top) and January 3, 2013. The top image shows extensive haze, low clouds, and fog over the region. The brightest areas tend to be clouds or fog, which have a tinge of gray or yellow from the air pollution. Other cloud-free areas have a pall of gray and brown smog that mostly blots out the cities below. In areas where the ground is visible, some of the landscape is covered with lingering snow from storms in recent weeks. (Snow is more prominent in the January 3 image.)

At the time that the January 14 image was taken by satellite, ground-based sensors at the U.S. Embassy in Beijing reported PM_2.5 measurements of 291 micrograms per cubic meter of air. Fine, airborne particulate matter (PM) that is smaller than 2.5 microns (about one thirtieth the width of a human hair) is considered dangerous because it is small enough to enter the passages of the human lungs. Most PM_2.5 aerosol particles come from the burning of fossil fuels and biomass (wood fires and agricultural burning). The World Health Organization considers PM_2.5 to be safe when it is below 25.

Also at the time of the image, the air quality index (AQI) in Beijing was 341. An AQI above 300 is considered hazardous to all humans, not just those with heart or lung ailments. AQI below 50 is considered good. On January 12, the peak of the current air crisis, AQI was 775 the U.S Embassy Beijing Air Quality Monitor—off the U.S. Environmental Protection Agency scale—and PM_2.5 was 886 micrograms per cubic meter.

1. Resources

2. Air Pollution in China: Real-time Air Quality Index Visual Map. Accessed January 14, 2013.
3. China Air Daily. Accessed January 14, 2013.
4. U.S Embassy Beijing Air Quality Monitor. Accessed January 14, 2013.

1. References

2. Associated Press, via Yahoo News (2013, January 14) Beijing warns residents after off-the-charts smog . Accessed January 14, 2013.
3. NASA (2010, September 22) New Map Offers a Global View of Health-Sapping Air Pollution.Accessed January 14, 2013.
4. NASA Earth Observatory (2012, March 23) Satellites Map Fine Aerosol Pollution Over China.
5. The New York Times (2013, January 14) China allows media to report alarming air pollution crisis. Accessed January 14, 2013.
6. Yahoo News (2013, January 14) China's air pollution problem slideshow. Accessed January 14, 2013.

NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response. Caption by Mike Carlowicz.

Instrument: 

Terra - MODIS - NASA

A River of Haze

As is often the case in the winter, a thick river of haze hovered over the Indo-Gangetic Plain in January 2013, casting a gray pall over northern India and Bangladesh. On January 10, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this image of haze hugging the Himalayas and spilling out into the Ganges delta and Bengal Sea.

The haze likely resulted from a combination of urban and industrial pollution, agricultural fires, and a regional meteorological phenomenon known as a temperature inversion. Usually the air higher in the atmosphere is cooler than the air near the surface, a situation that allows warm air to rise and disperse pollutants. However, cold air often settles over northern India in the winter, trapping warmer air—and pollution—close to the surface, where it has the greatest impact on human health.

Air quality has emerged as a significant problem for India and Bangladesh in the past decade. A study conducted by Tel Aviv University researchers and published in the American Journal of Climate Change found that levels of air pollution in large Indian cities increased at some of the fastest rates in the world between 2002 and 2010—faster even than rapidly-growing Chinese cities.

Many Indian cities recorded double-digit increases in pollution over the study period. Calcutta, the third-most populous city in India, saw an 11.5 percent increase in pollution; Bangalore (not shown in the image) had the largest increase of any Indian city: 34 percent. The research was based on information collected by MODIS and by the Multi-angle Imaging SpectroRadiometer (MISR) on NASA’s Terra satellite.

• References

• Pinhas, A. (2012, Nov.) AOD Trends over Megacities Based on Space Monitoring Using MODIS and MISR (PDF). American Journal of Climate Change. Accessed Jan. 11, 2013.
• Hindustan Times (2012, Nov. 30) India Tops China in Air Pollution Level Increase. Accessed Jan. 11, 2013.
• Time (2013, Jan. 8) India’s Air Pollution: Is It Worse Than China’s? Accessed Jan. 11, 2013.

1. Further Reading

2. NASA (2010, Sept.15) NASA Data Track Seasonal Pollution Changes Over India. Accessed Jan. 11, 2013.
3. New York Times (2012, Feb. 1) India’s Air the World’s Unhealthiest, Study Says. Accessed Jan. 11, 2013.

NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response. Caption by Adam Voiland.

Instrument: 

Aqua - MODIS - NASA

Haze over Eastern China

Haze hovered over eastern China on December 11, 2012. The haze, likely a combination of dust and air pollution, stretched from northern China across much of the coastal plain. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired this natural-color image on December 11, 2012.

Throughout November and December, thick haze has often blanketed this part of China. One common cause of poor winter air quality is a temperature inversion, in which a layer of cold, dense air gets trapped beneath a more buoyant layer of warm air. As long as the temperature inversion persists, pollution builds in the trapped pocket of air near the ground.

Airborne particles are often measured in microns (also micrometers), or one-millionth of a meter. Particles with diameters of 2.5 microns or smaller—about one-thirtieth the width of a human hair—are believed to pose the greatest health risks because they can lodge deeply in the lungs, according to the U.S. Environmental Protection Agency.

The U.S. Embassy in Beijing measures fine particles, known as PM2.5, and reports the measurements though the BeijingAir Twitter feed. The embassy reported air quality ratings ranged from “unhealthy to “very unhealthy” on the day this image was acquired.

In addition to the U.S. Embassy in Beijing, another site, China Air Daily, provides satellite images, ground-based photos, PM2.5 readings, and other air quality readings for multiple cities. Developed in response to a growing desire for more information on air quality, China Air Daily is a project of the Center on U.S.-China Relations at Asia Society.

1. References

2. AirNow. (2011, December 9) Air Quality Index. Accessed December 12, 2012.
3. U.S. Embassy in Beijing. (2012, October 22) BeijingAir. Accessed December 12, 2012.
4. U.S. Environmental Protection Agency. (2012, July 19). Fine Particle Designations: Frequently Asked Questions. Accessed December 12, 2012.
5. Zhu, C. (2012, October 17) A visual guide to Chinese air pollution. The Atlantic. Accessed December 12, 2012.

1. Link

2. China Air Daily

NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response Team at NASA GSFC. Caption by Michon Scott and Adam Voiland.

Instrument: 

Terra - MODIS - NASA

Delhi’s Air Pollution Worse Than Ever

Associated Press - The Presidential Palace enveloped in a blanket of smog, New Delhi, Nov. 3.

For a few days now, New Delhi has been enveloped in a thick blanket of smog – a mix of fog, car exhaust and manufacturing soot. Add a fair amount of dust and smoke to that.

Air pollution skyrocketed to alarming levels in the city on Wednesday, with the air quality index for PM 10 measuring 1000 in some areas.

That’s bad – even for a city known for its poor air quality.

By U.S. standards, PM 10 measuring more than 201 is classified as “very unhealthy,” and levels higher than 301 are considered “hazardous” to health. Pollution levels exceeding this, “would trigger health warnings of emergency conditions” according to a U.S. government body, which warned that “everyone should avoid any outdoor exertion.”

PM 10 levels measure pollutants with a diameter of 10 microns or less. Air pollution can also be measured in PM 2.5, pollutants with a diameter of 2.5 microns or less.

Over the past week, the air quality index for PM 10 in Delhi ranged from 600 to 800, according to data collected by state-run Delhi Pollution Control Board.

New Delhi’s current pollution levels are higher than those recorded before 2001, when, in a bid to improve air quality, the local government made it mandatory for buses and auto rickshaws to run on compressed natural gas.

In 2000, when the World Health Organization said the Indian capital was world’s fourth most polluted city, its average air quality index for PM 10 was 191.

In 2010, PM 10 was 249, according to data from India’s environment ministry. This makes Delhi India’s most polluted city. In comparison, PM 10 in Ludhiana and Allahabad, estimated to be the second and third most polluted cities in India, were 229 and 218, respectively. That year, major cities like Mumbai and Kolkata had PM 10 averages of 94 and 98, respectively.

Experts note that pollutant levels tend to peak in winter, because it’s drier and less windy than in the summer. But levels touching 1,000 are “shocking,” says Vivek Chattopadhyay, an air pollution analyst at the New Delhi-based Centre for Science and Environment. Mr. Chattopadhyay says PM 10 levels touched 500 in New Delhi last year, but escalating as high as 1,000 “is unheard of,” even by experts, he notes.

How did this happen?

“So far, there is no scientific consensus on the matter,” says Mr. Chattopadhyay. He believes that the mounting vehicle population of the capital is largely to blame.

The are an estimated 7.2 million vehicles in New Delhi – reportedly more than the total number of vehicles in Mumbai, Chennai and Kolkata combined.

Reports suggest mass-burning of agricultural waste in the neighboring states of Punjab and Haryana have also contributed to rising pollution levels in the capital.

New Delhi’s poor air quality is already taking a toll on the city’s estimated 12 million people, particularly those susceptive to respiratory disorders. Major hospitals have reportedly recorded a substantial increase in number of patients reporting chronic bronchitis and asthma, among other respiratory ailments.

A state-appointed environment body is scheduled to chalk out measures to curb high rates of pollution in the capital on Saturday.

“There is no cause for alarm. We are looking into the matter,” said an official from India’s environment ministry, declining to comment further.

By Thursday evening, though the dense layer of smog had cleared in most parts of central Delhi, zones across north and east Delhi still recorded alarming levels of PM 10. At 5 p.m., PM 10 recorded near University of Delhi was 910, while the overall level in the capital was still deemed “very unhealthy” by the earth sciences ministry.

- The Wall Street Journal

Haze over Eastern China

Thick haze hovered over eastern China on October 20, 2012. The haze stretched from Beijing southward, covering much of the coastal plain bordering Bo Hai and the Yellow Sea. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired this natural-color image the same day.
In many places, the haze was thick enough to completely hide the land or water surface below. A wide band of haze extended eastward over Bo Hai. In the west, isolated mountain peaks poked above the haze, which clogged valleys between the peaks.
Airborne particles are often measured in microns (also micrometers): one-millionth of a meter. Particles with diameters of 2.5 microns or smaller are believed to pose the greatest health risks because they can lodge deeply in the lungs, according to the U.S. Environmental Protection Agency. The U.S. Embassy in Beijing measures particles down to a size of 2.5 microns, known as PM2.5, and reports the measurements though the BeijingAir Twitter feed. On October 20, the same day that MODIS took this picture, reported air quality ratings ranged from “Unhealthy for Sensitive Groups” to “Hazardous.”

1. References

2. AirNow. (2011, December 9) Air Quality Index. Accessed October 22, 2012.
3. U.S. Embassy in Beijing. (2012, October 22) BeijingAir. Accessed October 22, 2012.
4. U.S. Environmental Protection Agency. (2012, July 19). Fine Particle Designations: Frequently Asked Questions. Accessed October 22, 2012.

NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response Team at NASA GSFC. Caption by Michon Scott.

Instrument: 

Aqua - MODIS - NASA

Smoke over Davis Strait

Smoke hovered over the Davis Strait and Labrador Sea in mid-June 2012. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color image on June 14, 2012. It shows a mixture of smoke and clouds over the icy region between Canada and Greenland.
The smoke likely originated from fires in Labrador. CBC/Radio-Canada reported that smoke from wildfires in the region prompted authorities to consider evacuating nearby communities, and MODIS observed thick smoke plumes on June 13.
Backward trajectories of the smoke calculated through the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) indicate that smoke traveled northeastward over the Labrador Sea and Davis Strait. “There is strong evidence that Labrador smoke got into the upper troposphere,” said Mike Fromm of the U.S. Naval Research Laboratory, “where it can often last a long time and travel great distances.”
The sea ice along the left edge of this image is tinted blue, probably due to surface melt.

1. References

2. CBC News. (2012, June 14) Crews tackle central Labrador fires. Accessed June 21, 2012.

NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response. Caption by Michon Scott with information from Charles Ichoku, NASA Goddard Space Flight Center; and Mike Fromm, U.S. Naval Research Laboratory.

Instrument: 

Terra - MODIS - NASA

Smoke Plume from Baikal over Bering?

(Click on image for larger view.)

A plume of smoke stretched across the Bering Sea on May 11, 2012, as the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite passed overhead. This natural-color image shows part of the Bering Sea, just off of far eastern Russia. The smoke appears dull blue-gray and darker than the surrounding clouds.

The smoke may have arisen from wildfires in the region around Lake Baikal, where numerous wildfires burned in early May. A model from the NOAA Air Resources Laboratory suggests that smoke from the Lake Baikal region would take just a few days to reach the Bering Sea.

In a study published in 2004, scientists tracked the movement of smoke from Russian wildfires, finding that it typically travels in one of two directions: northwest towards Scandinavia or east toward the Okhotsk Sea. The smoke blowing east often crosses the Bering Sea towards Alaska and Canada.

Smoke from the Lake Baikal region also appeared to be hampering air quality over China, as shown in this image.

Reference:
Damoah, R., Spichtinger, N., Forster, C., James, P., Mattis, I., Wandinger, U., Beirle, S., Wagner, T., Stohl, A. (2004) Around the world in 17 days – hemispheric-scale transport of forest fire smoke from Russia in May 2003. Atmospheric Chemistry and Physics, 4, 1311–1321.
NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response. Caption by Michon Scott with information from Ralph Kahn, NASA Goddard Space Flight Center.

Instrument:
Terra - MODIS - NASA

Haze Over Northern China

(Click on images for larger view.)

A heavy layer of haze hung over northern China on May 10, 2012, when the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA’s Terra satellite captured this image. Haze is common in this region, where people rely on coal for electricity and heat, and dust often blows in from the east, as well.
Numerous fires burning west of Lake Baikal in recent weeks have likely exacerbated the poor air quality in China. MODIS observed plumes of smoke billowing into the air from wildfires on May 7 and May 8, 2012 (above). According to the Russian news agency ITAR-TASS, more than 72 fires were still burning roughly 23,000 hectares of forests in Siberia as of May 14.

References:
MODIS Image of the Day. (2012, May 14) Smoke and fires in Eastern Russia. Accessed May 14, 2012.
ITAR-TASS. (2012, May 14) About 23,500 ha of Forests Afire in Siberia.
Accessed May 14, 2012.
NASA image courtesy LANCE MODIS Rapid Response. Caption by Adam Voiland.

Instrument:
Terra - MODIS - NASA

Southeast Asia Shrouded by Smoke

(Click on images for larger view.)

In March 2012, a thick pall of smoke and haze stemming from widespread agricultural and forest fires blanketed northern Thailand and parts of Laos and Burma. The haze pushed concentrations of airborne particulate matter to levels considered unsafe, disrupted service at Lampang airport, and prompted calls for action from leading Thai politicians.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this (top) natural-color image on March 4, 2012. It shows smoke across much of northern Thailand and a large band of pollution across central Thailand. On the same day, another instrument with a narrower swath and a higher resolution—the Advanced Land Imager (ALI) on NASA's Earth Observing 1 (EO-1) satellite—captured a closer view (bottom) of one of the many fires burning in the region.

Late winter and early spring are the dry season in Southeast Asia, where the climate is typically dominated by rainy and dry phases of the monsoon. During the dry season, fires of many kinds are common, including intentional fires—to clear crop residues, stimulate new growth of pasture, or clear forests—and accidental (escaped) wildfires.

The Thai provinces of Chiang Rai, Chiang Mai, Lamphun, Lampang, Mae Hong Son, Nan, Phrae, Phayao, and Tak were some of the hardest hit in March, with many seeing particulate levels more than twice as high as the 120 micrograms per cubic meter standard that's considered safe. In mid-March, the situation improved somewhat due to a heavy rain storm on March 11th and 12th.

References:
Bangkok Post. (2012, March 3) Haze Problem Hits New High. Accessed March 14, 2012.
Bangkok Post. (2012, February 28) Premier Orders Urgent Action to Tackle Haze in North. Accessed March 14, 2012.
Asia One. (2012, March 12) Rain Clears All Areas But Upper North. Accessed March 14, 2012.
NASA Earth Observatory image created by Jesse Allen and Robert Simmon, using EO-1 ALI data provided courtesy of the NASA EO-1 team. Caption by Adam Voiland.

Instrument:
Terra - MODIS - NASA

Winter Haze Blankets China

(Click on images for larger view.)

Fog and haze blanketed the North China Plain on January 10, 2012, making travel difficult. The Beijing airport cancelled 43 flights and delayed 80 more in the morning hours, when visibility dropped to 200 meters, said state news reports. Provinces across the plain reported low visibility.

The haze decreased visibility in satellite images too. A gray pall entirely blocks the ground from view in the top image, taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite in the early afternoon. Patches of white fog or low cloud hang below the gray haze. Winds had already begun to push the haze out of Beijing in the north, but the rest of the North China Plain still suffered from poor air quality. By the next day, when Aqua MODIS acquired the lower image, skies were mostly clear across the region.

One major constituent of haze is particle pollution such as dust, liquid drops, and soot from burning fuel or coal. Particles smaller than 10 micrometers (called PM 10) are small enough to enter the lungs where they can cause health problems. The density of PM10 reached 560 micrograms per cubic meter of air on January 10, said the Beijing Environment Protection Bureau. By contrast, U.S. cities exceed air quality standards when PM10 concentrations reach 150 micrograms per cubic meter averaged over a 24-hour period.

But most of the pollution that makes up haze isn’t PM10, it’s finer particles, smaller than 2.5 micrometers in diameter (PM2.5). These particles can embed themselves deep in the lungs and occasionally enter the blood stream. The fine particles are highly reflective, sending sunlight back into space. The Chinese government does not currently measure PM2.5, but the U.S. Embassy in Beijing reports their measurements hourly in a Twitter feed. On the morning of January 10, PM2.5 measurements were off the scale, though by afternoon they had dropped to moderate levels. The Beijing Environmental Bureau will start releasing PM2.5 measurements sometime before January 23, Chinese New Year.

The Chinese government is implementing a plan to monitor PM2.5 across the nation by 2016. Even with improved monitoring, winter haze events may be difficult to control. One common cause of poor air quality in the winter is a temperature inversion in which a layer of cold, dense air gets trapped beneath a more buoyant layer of warm air for several days. As long as the temperature inversion persists, pollution builds in the trapped pocket of air near the ground. Such inversions often contribute to poor winter air quality in the Beijing region.

References:
Lina, Y. (2012, January 11). Beijing city to release real-time air-quality data for local residents. Xinhua. Accessed January 12, 2012.
Shasha, D. (2012, January 10). Heavy smog grounds flights in Beijing. Xinhua. Accessed January 12, 2012.
United States Environmental Protection Agency. (2011, July 6). National Ambient Air Quality Standards. Accessed January 12, 2012.
United States Environmental Protection Agency. (2011, July 6). Particulate matter. Accessed January 12, 2012.
Wheeler, C. (2012, January 3). Air pollution hazardous to China’s economic health. The Globe and Mail. Accessed January 12, 2012.
Xinhua. (2012, January 10). PM2.5: Easy to monitor but hard to control. Accessed January 12, 2012.
NASA images courtesy the LANCE/EOSDIS MODIS Rapid Response Team at NASA GSFC. Caption by Holli Riebeek.

Instrument:
Aqua - MODIS - NASA

Haze over the Arabian Sea

(Click on image for larger view.)

A river of haze flowed over western India and the Arabian Sea in early January 2012. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color image on January 2, 2012. The plume of translucent haze terminates over the ocean, just northeast of a cloudbank.
The haze probably results from pollution, perhaps a combination of industrial and auto pollution. In the winter months, temperature inversions often trap haze along the southern slopes of the Himalaya. In general, the higher air sits in Earth’s atmosphere, the cooler it is. As warm air rises, it expands, cools, and disperses its pollutants. During the winter, however, cold air often slides down the southern face of the Himalayan Range and is subsequently trapped under a layer of warmer air. As long as the cold air stays below the warm air, the inversion holds the pollutants in place.
On January 4, 2012, The New York Times reported high pollution levels in the Indian capital of Delhi, and attributed the pollution to a combination of automobile pollution and temperature inversions.

References:
National Weather Service. What are temperature inversions? U.S. National Atmospheric and Oceanic Administration. Accessed January 5, 2012.
Timmons, H. (2012, January 4). A conversation with air pollution expert Dr. Gunasekar. India Ink. The New York Times. Accessed January 5, 2012.
NASA image courtesy MODIS Rapid Response Team at NASA GSFC. Caption by Michon Scott.

Instrument:
Terra - MODIS - NASA

Haze over Eastern China

(Click on image for larger view.)

Haze filled the skies over eastern China in early January 2012, extending southward from Beijing over the coastal plain near the Yellow Sea. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this natural-color image on January 6, 2012. In some places, the gray-beige haze is thick enough to completely hide the land surface below.
On January 6, Reuters reported that the city government of Beijing planned to release the results of stricter air pollution standards. Airborne particles are generally measured in microns, or micrometers. A micron is one-millionth of a meter. Beijing’s air-monitoring center has historically tracked particles at 10 microns or larger. Particles with diameters of 2.5 microns or smaller, known as PM2.5, are believed to pose the greatest health risks because they can lodge deeply in the lungs, says the U.S. Environmental Protection Agency. Beijing’s new air-quality standards are expected to monitor PM2.5 particles.

References:
Reuters. (2012, January 6). China to release stricter Beijing pollution measure. Accessed January 6, 2012.
U.S. Environmental Protection Agency. (2010, August 6). Fine Particle Designations: Frequently Asked Questions. Accessed January 6, 2012.
NASA image courtesy LANCE/EOSDIS MODIS Rapid Response Team at NASA GSFC. Caption by Michon Scott.

Instrument:
Aqua - MODIS - NASA