Original links are included though some may have expired.

The Numbers:

Micrograms of "particulate matter" per cubic meter of air, 2002:
New Delhi: 177
Cairo: 159
Calcutta: 145
Tianjin: 139
Chongqing: 137
...
World urban average: 60
...
Los Angeles: 36
New York: 22
...
Melbourne: 13
Perth: 13
Paris: 12

What They Mean:

Wheezing residents of the cities of China and India inhale about five times as much smoke and dust as lucky New Yorkers and Angelenos. So says the World Bank, surveying air pollution rates in 110 cities around the world, with a total population of 530 million, as of 2002. Its "Little Green Data Book" suggests a world urban average of 60 micrograms of "particulate matter" -- soot, ash, dust, etc. -- per cubic meter of air; World Development Indicators 2006 tables find China and India home to 18of the world's 20 smokiest and dustiest towns.

Particulate matter levels top out at 177 micrograms per cubic meter of air in New Delhi. The rest of the top five include Cairo, Calcutta -- officially "Kolkata" since 1999 -- Tianjin and Chongqing, all with levels above 130 mikes per m³. Guiyang, Chongqing, Tehran, and Taiyuan lead in acid-rain precursor sulfur dioxide; for this pollutant, 14 of the 20 highest rates are in Chinese cities. Milan, a bit curiously, has the ignominious lead in nitrogen dioxide levels at 248 micrograms per cubic meter -- twice the rates of Beijing and Mexico City and five times that of Bucharest.

By comparison, the residents of New York and Los Angeles inhale 22 and 36 mikes of dust in each cubic meter of air. Parisians are healthier still; Paris' 12 micrograms per cubic meter is the lowest for the 110 cities in the Bank's survey. Perth, Melbourne, Stockholm, and Oslo are just a bit higher at 13 micrograms; the least-smoky developing-country city is Capetown, at 15 micrograms. (But Capetown has a high nitrogen dioxide count; the gas is pumped out by a power plant north of the city.)

The health consequences, according to the U.S. Environmental Protection Agency, are rather serious: "High particle levels, have been associated with problems such as reduced lung function and the development of chronic bronchitis and even premature death." But comparing the 2002 survey to one done in 1999 gives reason for cautious optimism. Seventy-three cities report lower levels of smoke and dust, and only 19 report higher levels. The sharpest improvements are Manila's 30 percent drop, from 60 to 42 micrograms per cubic meter, and the 20 percent drops in Paris and Mexico City. But Birmingham (in England, not Alabama) seems to have gotten smokier, reporting a jump from 17 to 26 micrograms per cubic meter. Accra likewise reports a 29 percent jump and Kuala Lumpur and Singapore 17 percent each.

Further Reading:

PPI's Energy and E nvironment project:
http://www.ppionline.org/ppi_ka.cfm?knlgAreaID=116

The World Bank's city-by-city data for 2002 seems unavailable on line, but is Table 3.13 in World Development Indicators 2006. The 1999 survey, though, is at:
http://devdata.worldbank.org/wdi2005/Table3_13.htm

And the "Little Green Book" is at:
http://web.worldbank.org/
WBSITE/EXTERNAL/TOPICS/ENVIRONMENT/EXTEEI/
0,,menuPK:408056~pagePK:149018~piPK:149093
~theSitePK:408050,00.html

In the United States: Environmental debates generally, and debates over climate change in particular, often pit jobs and growth against health and the quality of life. Why? Long-term American air-quality statistics show all major air pollutants down since the Clean Air Acts of 1970 and 1990. In the 35 years between 1970 and 2005, U.S. emissions of carbon monoxide fell from 197 to 89 million tons; of particulate matter from 12 to 2 million tons ^*; of sulfur dioxide from 31 to 15 million tons; of nitrogen dioxide from 27 to 19 million tons; and of airborne lead from 220,000 to 3,000 tons. Meanwhile American GDP tripled from $4.3 to $12.5 trillion (real 2005 dollars) and private-sector employment rose from 70.5 million to 134.5 million. See for yourself:

• U.S. air pollutant trends since 1970 from the EPA:
  http://www.epa.gov/airtrends/2006/econ-emissions.html


• Employment totals from the Bureau of Labor Statistics:
  http://data.bls.gov/PDQ/outside.jsp?survey=ce


• GDP data from the Bureau of Economic Analysis:
  http://www.bea.gov/bea/dn/home/gdp.htm

^* Data on small particles of 2.5 microns or less is not as encouraging; these are thought more threatening to health, and emission rates have not fallen rapidly.

South Africa's Capetown regional environmental program:
http://www.capeaction.org.za/

2008 -- Beijing ranks 97^th among the 110 cities for particulate matter emissions, 84^th out of 100 for sulfur dioxide, and 87^th out of 90 for nitrogen dioxide. In bidding for the 2008 Olympics, Beijing's city government pledged to meet World Health Organization standards for urban air quality before the Olympic torch arrives in the summer of 2008. Its plan involves reducing use of coal, improving the fuel-quality and emissions laws, and planting trees in rural lands and parks around the city to protect Beijing from silt blown into the city from the Gobi desert. Chinese lawmakers may also restrict private car use in the two months before the Olympics, aiming to cut the number of vehicles on the Beijing roads by half. The Shanghai Daily reports on progress, as of August 2006:
http://www.china.org.cn/english/environment/177419.htm

Beijing's city website is at:
http://www.ebeijing.gov.cn/
The English-language site does not seem to comment on the environment, but does solicit votes for a contest to name the "ten best classic love stories." The story must involve at least one Chinese person, and "must shock people but also be healthy."

And last -- the Patna Daily reviews the results of "Kolkata" after six years and offers helpful suggestions for spending millions on more name-changes, e.g. by spelling "Lucknow" backward, changing "Delhi" to "Dilli," etc.:
http://www.patnadaily.com/features/kolkata.html