Worst Air in the World?

We hear in the news about horrible air quality in the developing world.  Stories about Chinese air quality are everywhere.

Here in the Central Valley it is conceded that we have the worst air in the nation but surely it is far better than  places like China.  So, let’s make the comparison.

Who had the worst air over the holiday season, Beijing, China or the Central Valley of California?

The chart below gives the 24 hour PM 2.5 values from the US Embassy monitor in China and the same values for monitors in the southern half of the San Joaquin Valley between Fresno and Bakersfield.

The time period is three weeks surrounding the holiday season in the US from December 16, 2013 to January 5, 2014.

Using the 100 micrograms per cubic meter mark to separate really bad air from absolutely killer air, there were seven days when you would not want to go outside without a good mask over your face in China.  The Central Valley only had 2 such days when virtually no one should be outside.

Out of the 21 days, the Central Valley had no days below the World Health Organization recommended safe level for 24 hours of 25 micrograms per cubic meter.  China had 3 such days.

In total over the 21 days, the Central Valley had worse air on 13 of them.  In other words, there was worse air in the Central Valley than in China about 2/3 of the time over this past holiday season.

If we average the 21 days, the air in China was about 15% worse than in the Central Valley.

If we eliminate the extremes, or the best 4 days and the worst 4 days in each place, then the Central Valley had the worst average by about 4%.

Conclusion:  Both places had horrible air and the Central Valley is clearly in the category of the “developing world” in terms of air pollution.