The U.S. Government lists the poverty rate as $10,890 for individuals, and $22,350 for a family of four. Reports filed at the Centers for Disease Control (CDC) note a higher prevalence of asthma among the poor or near poor.
This is especially important because poverty seems to be rising in the U.S. The New York Times, "Soaring Poverty Casts Spotlight on 'Lost Decade," reported on the latest Census Bureau statistics that show that the number of Americans living under the poverty line is 46.2 million people, the highest rate in 52 years.
It's difficult to pinpoint any one cause, although experts have listed all of the following as possible reasons why poverty is linked to worse asthma control:
1. High cost of asthma medicine: The cost of my monthly supply of asthma medicine comes to over $100, and that's with health insurance. So I can easily understand why some asthmatics may have to forgo this cost, especially when their feeling good. This can lead to worse asthma control because studies show that most asthmatics who take their asthma controller medicines every day can live relatively normal lives. Not taking asthma controller meds daily can lead to poorly controlled asthma.
2. High copays: To offset the high cost of prescriptions, many insurance companies are shifting the burden to customers by making them pay higher copays. My personal copay for medicine like Albuterol is $10, but for medicines like Advair and Singulair it's a percentage of the cost of the medicine. For Advair I pay $40, and Singulair I pay $30. A study published in the American Journal of the American Medical Association revealed that medication use among children 5-18 years of age declined slightly among those who pay a high copay, yet among the same group asthmatics were significantly more likely to be hospitalized for asthma.
3. Lacking health insurance: While high copays discourage those with health insurance from buying asthma medications, many at or near the poverty line don't have health insurance and are forced to prioritize food and shelter over asthma medications.
4. High rate of smoking: A report by the Australian Institute of Health and Welfare showed that asthmatics of poor socioeconomic status were more likely to continue smoking despite education about the hazards of smoking. This same group is also more likely to smoke in front of children. I wrote about how smoking can make asthma worse here.
5. Poor housing: People who live in poverty are more likely to live in conditions that lend themselves to poor asthma outcomes. For example, cockroaches, poorly constructed buildings, mold, and dust mites are all things known to make asthma worse, and that most of us can get rid of, fix or avoid. Yet people of low socioeconomic status may be unable to remedy these problems. This results in daily exposure to asthma causes and triggers, and this easily results in poorly controlled asthma

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