Air quality measures

In the heat of the summer, keep an eye on the air quality index.
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In the heat of the summer, keep an eye on the air quality index.

On the hot, hazy days of summer, you may hear references to the air quality index (AQI) in your local weather reports. AQI is a measure of how healthy it is to breathe the air on a given day. The index is calculated based on the levels of five major air pollutants---ozone, particulate matter, carbon monoxide, sulfur dioxide and nitrogen dioxide---and reported as a color code. The elderly, children and people with asthma and other health issues are most likely to be affected by poor air quality. But daily fluctuations in the AQI may also affect your horse’s respiratory health.Here is what the AQI color codes mean:


• “Green” indicates good air quality, with no adverse health effects expected. All horses should be able to exercise to their level of fitness without having trouble breathing.

• “Yellow” corresponds to moderate air quality, when unusually sensitive people may have trouble breathing after prolonged exertion. Horses with active heaves or those recovering from respiratory disorders are best kept to very light exercise on these days.

• “Orange” means that the air is unhealthy for sensitive individuals. On these days, avoid prolonged exertion if your horse has a history of heaves, even if he isn’t in the midst of a flare-up. The poor air quality could easily trigger one.

• “Red” indicates that the air is unhealthy even for those without respiratory problems. On these days, curtail outdoor activities, for horses and people alike. Spend your time walking slowly on the trails or stick with groundwork.

If your horse appears to be having trouble breathing on a day with a poor AQI, stop any work and bring him indoors, if possible, to a cool barn with good air circulation. A stall with a box fan is a good option, as long as the fan is actively bringing in fresh air, not just stirring up dust particles. If your horse does not appear more comfortable within a half-hour, or if his condition worsens in that time, call your veterinarian.

This article first appeared in EQUUS issue #443.