This report is an update and extension of our original October 2011 research and report about air quality and hospital admissions for asthma in Los Angeles. Our data now cover the period 2010-2011.
Soot and smog were not correlated with emergency admissions for asthma at a large Los Angeles hospital during 2010-2011.
The U.S. Environmental Protection Agency asserts that ambient ozone (smog or O3) and fine particulate matter (soot or PM2.5) exposures increase hospital emergency admissions for asthma.
The EPA claims, for example, that reducing the 8-hour ozone standard from the current 75 parts per billion (ppb) to 65 ppb would reduce the number of asthma exacerbations by 38,000 and related hospitalizations by 11,000 annually.
The EPA claims that its Cross-State Air Pollution Rule, which is intended to reduce O3 and PM2.5 levels in 30 states will prevent 400,000 cases of aggravated asthma and 19,000 hospital and emergency department visits.
So we undertook to compare ozone and PM2.5 levels with hospital admissions for asthma in Los Angeles, which has some of the “worst” air quality in the U.S.
Through the Freedom of Information Act, we obtained the daily tally of hospital admissions for asthma from the Veterans Administration West Los Angeles Medical Center for the period January 1 2010 to December 31, 2011.
We correlated these tallies with daily O3 and PM2.5 maximums as collected by the California Air Resources Board for the South Coast Air Basin, the air quality management district that includes the Los Angeles area.
We correlated the air quality and hospital admissions data on a same day, 1-day lag, 2-day lag and 3-day lag bases.
The Pearson correlations and 95% confidence intervals between o3 and PM2.5 levels in the Los Angeles’ area and hospital admissions are presented in the table below. A Pearson’s correlation of 1.0 indicates perfect correlation, a −1.0 indicates perfect inverse correlation and 0 indicates no correlation. All the correlations presented below are essentially zero.
|Pollutant||Pearson’s correlation||95% Confidence Interval|
|O3 (No lag)||-0.061||(-0.132, 0.011)|
|O3 (1-day lag)||-0.033||(-0.105, 0.039)|
|O3 (2-day lag)||-0.058||(-0.13, 0.014)|
|O3 (3-day lag)||-0.084||(-0.155, −0.012)|
|PM2.5 (No lag)||0.011||(-0.061, 0.083)|
|PM2.5 (1-day lag)||0.090||(0.018, 0.161)|
|PM2.5 (2-day lag)||-0.025||(-0.097, 0.047)|
|PM2.5 (3-day lag)||0.014||(-0.059, 0.086)|
These results indicate that maximum ozone and fine particulate matter levels in the Los Angeles area were not correlated with admissions for asthma at the VA West Los Angeles Medical Center for the period January 1, 2010 to December 31, 2011.
If ambient O3 and PM2.5 were associated with hospital admissions for asthma, one could reasonably expect to find a correlation in these data. But we did not.