The Air Quality Index, or AQI, is a daily feature of city life in India, but what do the numbers and colours actually mean for our health? This guide breaks down each pollution level and identifies who is most at risk and when to take action.
First, Who Are the 'Sensitive Groups'?
Before diving
into the numbers, it's crucial to understand who falls into the 'sensitive' or 'vulnerable' categories. Health advisories frequently mention this group because they are the first and most severely affected by rising pollution. This includes children and teenagers, whose lungs are still developing; older adults, who may have decreased lung function; pregnant women; and anyone with pre-existing medical conditions. The most common conditions of concern are respiratory illnesses like asthma and chronic obstructive pulmonary disease (COPD), as well as cardiovascular diseases. People in these groups can experience symptoms at much lower AQI levels than the general population.
Good (0-50) & Satisfactory (51-100)
When the AQI is in the 'Good' (green) or 'Satisfactory' (yellow) range, air quality is considered acceptable and poses little to no risk for most people. You can generally enjoy outdoor activities without concern. However, even at the upper end of the 'Satisfactory' level, a very small number of people who are unusually sensitive to air pollution might experience minor breathing discomfort. For the vast majority of the population, these levels do not require special precautions.
Moderate (101-200)
This is the 'Orange' zone, where health concerns begin for vulnerable populations. While the air quality is still acceptable for the general public, it can cause breathing discomfort for people with lung disease, asthma, and heart conditions. Children and older adults may also begin to feel the effects. Symptoms at this stage can include coughing, wheezing, or tightness in the chest. The official advice for sensitive groups is to reduce prolonged or strenuous outdoor exertion. For instance, a long run might be ill-advised, but a short walk is likely fine. Healthy individuals are unlikely to be affected.
Poor (201-300)
Entering the 'Red' zone, the 'Poor' AQI level is where the general, healthy population may start to notice effects, especially during prolonged outdoor exposure. You might experience coughing, throat irritation, or shortness of breath. For sensitive groups, the risks become more serious, and even short exposure can cause significant breathing discomfort. At this stage, it is recommended that vulnerable individuals avoid all outdoor physical activities. Healthy adults should also consider reducing heavy outdoor exertion to minimise exposure.
Very Poor (301–400)
Classified as 'Purple', a 'Very Poor' AQI triggers a more serious health alert. Everyone may now experience more significant health effects. For the general population, prolonged exposure can lead to respiratory illness. For those with existing heart or lung conditions, the impacts can be pronounced and severe even after short exposure. At this level, the advice becomes stricter: sensitive groups should remain indoors and keep activity levels low. The general public should avoid all outdoor physical activity, especially during the morning and late evening hours when pollution can be more concentrated.
Severe (401–500+)
The 'Maroon' or 'Severe' category represents hazardous air quality and emergency conditions. At this point, the entire population is likely to be affected by serious health issues. Even healthy individuals can experience respiratory symptoms and other health problems with minimal exposure. For sensitive groups, the situation is dangerous. The official advisory is for everyone to avoid all outdoor exertion and remain indoors as much as possible. Exposure to such high levels of pollution can aggravate existing diseases and cause lasting damage.
