This is the second in a series of posts comparing Beijing's air quality to that of other Olympic host cities. Here, I explore the air quality of Los Angeles during the 1984 Games.
Summary: Lack of available data makes directly comparing the air quality during the Los Angeles Olympics to that of Beijing challenging. The only air quality data I could find for Los Angeles in 1984 are concentrations of ozone and Total Suspended Particles (TSP). Unfortunately, PM10 measurements did not begin in Los Angeles until 1988, and no ozone concentration data is available for Beijing.
Still, some rough comparisons may be made by examining LA's TSP data as well as PM10 data from 1988 on. Here, I conclude the following:
1) Beijing's 2007 annual average PM10 concentration (148 ug/m^3) was approximately twice as high as that in LA in 2007 (76 ug/m^3), and about 1.4 times higher than that in LA in 1988 (104 ug/m^3)
2) Since the car ban went into effect in Beijing on 7/20, the average PM10 concentration has been 111 ug/m^3, 7% higher than LA's 1988 average.
3) Using a rough estimate that PM10 in LA is about 55% of TSP, I estimate the average PM10 concentration in LA during the 1984 Olympics to be around 68 ug/m^3 (corresponding to a Chinese API of 59), more than double the concentration during the Atlanta Games.
Analysis: Again, let's start by examining data sources. The best data source I found was Air Quality Data Statistics from the California Air Resources Board. For an overview, I chose Air Quality Trend Summaries and queried PM10 for the South Coast Air Basin. Unfortunately, the earliest data available in this query is from 1988. Prior to 1988, it seems that the EPA only required the measurement of Total Suspended Particles (TSP), not PM10. The difference between TSP and PM10 is that TSP includes all particles of all sizes, whereas PM10 only includes particles smaller than 10 microns in size. The smaller particles are more damaging to human health because they penetrate deeper into the lungs.
Below is a graph of the available annual PM10 average data for the South Coast Air Basin and Beijing:
It is clear from this graph that Beijing's annual PM10 concentration is still significantly higher than that in Los Angeles, even looking all the way back to 1988.
But, as mentioned in my post on Atlanta, during the Olympics we care less about yearly averages and more about daily averages. And, indeed, the air quality in Beijing recently has been considerably better than the 2007 average. Specifically, the average PM10 concentration in Beijing since 7/20 has been 111 ug/m^3, just 7% higher than LA's 1988 average (104 ug/m^3).
Though PM10 data is not available for LA during the Olympics, it may be worth taking a look at the TSP data to see what we can learn. Summary data for the area is not available prior to 1988, but we can query individual monitoring stations going back to 1983. I chose to query a 10-week period in 1984 starting with July 1. Though there are 12 monitoring sites in Los Angeles, daily data only exists for two stations: Los Angeles - North Main St. and Azusa. This data is shown in the graph below:
During the Olympic period (7/28/84 - 8/12/84), the average TSP concentration at LA - North Main St. was 113 ug/m^3, while the average at Azusa was 136 ug/m^3. I will take an average of these two readings, 124 ug/m^3, as a rough estimate of the TSP concentration in LA during the 1984 Olympics.
Of course, the most obvious question then is: what percentage of the TSP is PM10? I'm not sure the best way to answer this, but I suppose it's reasonable to make a rough approximation by comparing TSP and PM10 data for a time period in which both are available. Towards this goal, I queried TSP and PM10 for the first available year - 1988 - for the Los Angeles - North Main St. station, and compared the TSP to PM10 results for all common data points throughout the year. The result is that on average, the PM10 concentration was 55% of the TSP concentration.
Applying this 55% factor to the Olympic TSP data described above yields an estimated PM10 concentration during the Los Angeles Olympics of around 68 ug/m^3, corresponding to a Chinese API of 59. This result is significantly lower than even the 1988 average, but is consistent with descriptions of considerably improved air quality in LA during the 1984 Games.
Conclusion: Though it is impossible to compare directly the air in Beijing with the air in Los Angeles during the 1984 Olympics, it is clear that, from the perspective of PM10, Beijing's average air is considerably more polluted than that in Los Angeles even in the late 1980's. During the 2008 Olympics, for Beijing's air to be considered equal quality to Los Angeles during the 1984 Olympics, Beijing's API during the Games should average 59 or below.