The color purple on an air quality map is a serious warning sign. This color is part of the Air Quality Index (AQI), a standardized system used to communicate how clean or polluted the air is. A purple reading signifies that local air pollution levels pose a significant health concern. Understanding this index is the first step toward protecting yourself and your family from associated health risks.
How the Air Quality Index Works
The Air Quality Index (AQI) is a numerical and color-coded scale running from 0 to 500 that translates complex concentrations of various air pollutants into a single, easy-to-understand reading. This index helps communicate the health risks posed by common pollutants like ground-level ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide, and fine particulate matter (PM2.5). The higher the AQI number, the greater the level of pollution and the more serious the resulting health concerns become. An AQI value of 100 generally corresponds to the national air quality standard set to protect public health.
Air quality is categorized into six distinct levels, each assigned a specific color and health descriptor. The lowest levels, categorized as Green (Good) and Yellow (Moderate), indicate satisfactory air quality with little or no risk for the general population. As the air quality degrades, the colors progress to Orange (Unhealthy for Sensitive Groups) and Red (Unhealthy), signaling a growing risk.
The “Very Unhealthy” Purple Designation
The purple color on the Air Quality Index scale corresponds to the “Very Unhealthy” category, a critical designation that triggers a health alert. This level encompasses AQI values ranging from 201 to 300, a range where the air quality is extremely poor. At this level, the health warnings shift from concerning only sensitive individuals to affecting the entire population.
The primary pollutant driving the AQI into the purple range is often fine particulate matter, known as PM2.5. These microscopic particles are 2.5 micrometers in diameter or smaller, making them tiny enough to bypass the body’s natural defenses in the nose and throat. Once inhaled, PM2.5 particles travel deep into the lungs and can even cross into the bloodstream, where they can cause widespread inflammation. This level of air pollution indicates that the concentration of these harmful particles is now high enough to pose a serious and immediate threat to everyone.
Health Risks During Purple Air Quality
Breathing air in the Very Unhealthy range significantly increases the likelihood of experiencing noticeable physiological effects. Even healthy individuals may show strong symptoms and a reduced endurance for physical activities when the AQI is purple. Common short-term symptoms include coughing, wheezing, throat irritation, and a burning sensation in the chest due to irritation of the eyes and breathing passages.
For vulnerable populations, such as children, older adults, and people with heart or lung conditions, the risks are particularly elevated. Exposure can aggravate existing respiratory conditions like asthma and Chronic Obstructive Pulmonary Disease (COPD), leading to more frequent or severe attacks. Fine particulate matter can trigger serious cardiovascular events, including heart palpitations or an increased risk of heart attack. Exposure at the purple level can significantly reduce lung function and trigger other illnesses even in otherwise healthy people.
Essential Steps for Protection
When the air quality reaches the purple designation, the most effective protective measure is to minimize all outdoor exposure. Everyone should avoid all outdoor physical activity, and sensitive groups should remain indoors entirely.
To keep indoor air clean, windows and doors must remain closed. Using a high-efficiency air filtration system, such as a portable air cleaner with a HEPA filter, is recommended to continuously scrub the air inside your home. If outdoor exposure is unavoidable, wearing a properly fitted N95 or KN95 respirator mask can offer protection against the fine particulate matter; surgical or cloth masks are insufficient for filtering these tiny particles. Those with existing heart or lung conditions should keep rescue medications readily available and contact their healthcare provider if symptoms like shortness of breath or unusual fatigue develop.