Southern Asia Pollution
Cold winter weather and burgeoning industrial economies have made for difficult breathing in Asia and the Middle East this January 2013. Pollution is epidemic. News reports from Ankara, Tehran, Beijing, and other cities have described hazy skies with very low visibility; restrictions on driving, factory operations, and outdoor activity; and hospitals full of people with lung ailments. The map with this story shows the concentration of nitrogen dioxide (NO2 or NOx) in the atmosphere above southwestern Asia from January 1—8, 2013. Shades of orange reflect the relative abundance of NO2, while grays show areas without usable data (cloud cover, for instance). The data were acquired by the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite. OMI measures the visible and ultraviolet light scattered and absorbed by Earth’s atmosphere and surface. The presence of NO2 causes certain wavelengths of light to be absorbed.
The "hot spots" are Tehran in Iran, Northern India (indeed all India is sprinkled with NO2), the Persian Gulf, Istanbul Turkey, and the eastern Mediterranean coast.
NOx reacts with ammonia, moisture, and other compounds to form nitric acid vapor and related particles. Small particles can penetrate deeply into sensitive lung tissue and damage it, causing premature death in extreme cases. Inhalation of such particles may cause or worsen respiratory diseases, such as emphysema or bronchitis, or may also aggravate existing heart disease.
Reports from Tehran and other cities note that the air is also full of particulate matter, which is easier to spot from the ground but harder to measure from space. Desert landscapes, snow cover, and clouds all make airborne particles difficult to measure with nearly all current satellite instruments. Given that aerosols and NO2 usually arise from the same fuel-burning emissions, the presence of one usually indicates the presence of the other.
The large increase in natural gas prices and the distribution of free coal by municipalities prior to local elections has led to an enormous jump in pollution levels in Ankara, reaching as high as 9,350 micrograms of particulate per cubic meter. The US EPA air quality standard for a 24 hour exposure is only 150. According to the World Health Organization, 1,000 micrograms of pollution is an alarming level and 2,000 micrograms might cause death.
In winter, several trends can combine to significantly increase harm to air quality. When the weather is cold, people burn more fuel to keep warm. In many developing economies, the most widely available fuel is coal, which can produce more particulates and smog-producing compounds than other forms of energy.
At the same time, the weather is conspiring to keep these emissions close to the ground. In most times of year, the air higher in the atmosphere is cooler than the air near the ground, allowing warm air to rise and carry pollution up and away from its source. But in the winter, temperature inversions can form, where the air near the ground is cooler than the air at higher altitudes. Polluted surface air rises a bit, but then runs into warmer air masses above and stays trapped near the surface.
Winter also can bring strong high pressure systems, which generate less wind and more stable atmospheric conditions that also hold surface air in place. Even geography can concentrate the air pollution. If a city is surrounded by mountains (such as Tehran), cold air may continually sink down into the basin and the hills may temper or redirect the winds that can clear the air.
For further information see Asia Pollution.
Map image via NASA.