Every breath you take

Air quality should be monitored to determine appropriate work sessions
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Sep 01, 2004

What is your number? We all have numbers that are important to us as individuals—our social security number, our telephone number, maybe even our bed's sleep number. But there should be another number that is important to you, too, and that is an AQI number. The Air Quality Index (AQI) is a means of reporting daily air quality, and it is a measure of how clean or polluted air in a specific location is. The AQI number directly relates to the possible health and environmental effects of air, as well as the calculated health risks within a few hours to days after breathing it.


Particulate matter can be large enough and dark enough to be seen, such as in dust, dirt, soot and smoke, or it can be so small that it can be detected only by electron microscope.
Equine veterinarians commonly are called upon to diagnose and treat horses with respiratory problems, and those concerns are frequent especially during the hazy, hot, humid months of summer. Studies done in 2000 actually show respiratory problems to be second only to lameness as a major cause of lost training time among horses used for racing or performance. Many respiratory problems in horses and humans are very closely linked to the quality of inhaled air and to the amount and types of allergens and pollutants in that air. Conditions such as chronic obstructive pulmonary disease (COPD), bronchitis, and other asthma-related problems that are air-quality sensitive also are rarely curable. Veterinarians stress management of these horses with their clients, and management usually involves both medical and environmental means. Horses suffering from heaves are commonly treated with anti-inflammatories, antihistamines, steroids, bronchodilators and various inhalant compounds. Owners of these horses are encouraged to rest them when the weather is bad, to wet their hay, to use fans and reduced-dust bedding and other measures designed to improve air quality. Often, however, the actual quality of that air and the nature of the impurities in it are unknown. So it is difficult for veterinarians to identify those horses that react with fungal spores from those that react to dust or ozone. DNA-based allergy testing can help in this identification process, but we still need to know what is in the air that we all breathe.

This is where AQI comes in and where veterinarians might be able to help their clients take a giant step toward successful management of horses with allergic inflammatory responses. AQI is calculated by the Environmental Protection Agency (EPA) focusing on the five major air pollutants regulated by the Clean Air Act. These pollutants are ground-level ozone, particulate matter, carbon monoxide, sulfur dioxide and nitrogen dioxide. Research has shown that these pollutants represent the greatest dangers to health, and the EPA has set national air-quality standards for them. The EPA makes measurements and calculations for all of these pollutants, and this information is then factored into an AQI number for a given location within the United States. A value of 100 is the national standard. Values below this number generally are thought to be satisfactory. Values of 0-50 are considered good, and values of 50-100 are moderate, meaning that only those animals and humans with pre-existing respiratory problems might experience health concerns. Values from 101 to 150 are considered unhealthy for sensitive individuals, and values from 150 to 200 are unhealthy for everyone. Levels beyond this are labeled very unhealthy and then hazardous and correspond to serious health concerns and emergency conditions.

The five major air pollutants merit a closer look because these different respiratory irritants are found in different locations across the country, and they seem to affect individuals differently. David Hurley, a Ph.D. microbiologist working at the University of Georgia College of Veterinary Medicine and exploring the interaction of various pollutant particles on respiratory health, points out that some horses, just like some humans, might have fungal trigger levels while others can have ozone trigger levels. These would be the levels of various irritants that initiate an inflammatory response in a specific individual.


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"Research in various human pediatric medical departments is currently aimed at identifying the particular levels of various irritants that cause these responses," Dr. Hurley says. "But equine medicine is not quite there yet."

Knowing more about the specific pollutants will help isolate and identify their effects.