What is 'Unhealthy' according to the AQI?

The Air Quality Index (AQI) is a way to measure air pollutants regulated by the Clean Air Act, and it ranges from 0 to 500. The pollutants monitored are ozone, particulate matter, carbon monoxide and sulfur dioxide. If air levels are above 100, then the quality is said to be ‘unhealthy’ for sensitive groups.

What causes unhealthy air quality?

Pollution from sources such as industrial areas, combustion processes, and busy roadways, can impact the air quality around us. The weather is also a factor; higher temperatures and sunlight cause the chemicals in the air to stay lower to the ground, creating ozone pollution.

People with a history for respiratory sensitivity and children are usually more susceptible to showing signs of health effects. Time spent outside greatly increases the risk, especially if you are exercising during peak traffic periods.

Case in Point – Fire on the Houston Ship Channel and in Crosby

In March 2019, a fire spread onto several storage tanks located along the Houston Ship Channel, each containing 80,000 barrels of fuel. The fire generated a large, black plume which shadowed the area for 4 days. Several chemicals, including benzene, were detected in higher concentrations near the incident. As the fire continued, the AQI increased, resulting in unhealthy levels (AQI of 100, or greater) in the immediate area.

As the fire progressed, the City of Houston’s AQI also continued to increase. Although the air quality in the City had an average AQI of 93, it was recommended that residents remain indoors as much as possible.

In early April 2019, a fire at a chemical plant in Crosby, TX. A transfer line to a tank was ignited and a fire spread to a chemical storage warehouse causing a large plume of smoke. This fire was extinguished in about 6 hours. People with respiratory sensitivities would be most susceptible to this short-term irritation.

Going about your day

Checking the AQI before planning your day can influence a healthy routine. Exercising outside during less busy traffic times could also reduce health risks, especially for children or other sensitive groups.

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