Many people often ask me how I got the 300+ AQI number, especially when they check and see it as much lower.
This can be confusing, but let’s break it down to understand what AQI (Air Quality Index) is and why it fluctuates so much, both hour-to-hour and day-to-day.
What is AQI?
The AQI is a scale used to measure air pollution levels and its impact on health. It takes into account several pollutants, such as PM2.5 (fine particulate matter), PM10, nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), and carbon monoxide (CO).
The AQI in Yerevan is primarily measured using ground-based monitoring stations, many of which are provided by IQAir, an air quality technology company with German made monitors, founded in 1963 and headquartered in Switzerland.
These stations continuously record real-time air quality data, using the levels of the pollutants listed above. This live data is then used to calculate the AQI, which reflects the overall air quality at any given time.
Each of these pollutants can affect our health in different ways, and the AQI value gives us a quick indication of how safe or dangerous the air is to breathe:
🟢 0-50: Good
🟡 51-100: Moderate
🟠 101-150: Unhealthy for sensitive groups
🔴 151-200: Unhealthy
🟣 201-300: Very unhealthy
🔵 300+: Hazardous
So why does AQI vary so much?
1. Hour-to-Hour Variations:
Pollution levels can change due to traffic, weather conditions (strong winds, rain, snow, humidity), and temperature. During rush hours, for example, vehicle emissions can spike, causing a rise in AQI. Higher humidity can cause pollutants like particulate matter to clump together, making them heavier and allowing them to settle out of the air more quickly.
2. Day-to-Day Changes:
Daily factors such as industrial emissions, dust from construction, dust storms, or even use of burning fuels for heat can significantly alter the AQI.
3. Month-to-Month Shifts:
During colder months, Yerevan experiences a phenomenon known as the basin effect, where cold air gets trapped under a layer of warmer air. Additionally, the city often experiences a lack of strong winds during this time. This natural weather pattern prevents pollutants from dispersing and causes them to accumulate, leading to higher AQI levels.
In warmer months, less pollution is trapped, and will show lower AQI numbers (mostly yellow or even green). Ozone can still be a risk, as it thrives in heat and though it may not alter the AQI significantly, in localised traffic congested areas it can cause acute health effects.
Why Monthly and Yearly Averages Matter
When people see a “green” or “yellow” AQI, especially during summer, it might seem like there’s no pollution problem. But it’s essential to look at the average AQI over time, not just daily snapshots, to understand the long-term trends.
Armenia’s average yearly pollution has exceeded the WHO guideline from 5 to 9 times for the past few years (2020 was at the lower end at 5x the WHO guideline due to the lack of cars from the COVID lockdown).
On our homepage you can find PM2.5 levels for each month in 2023 (2024 data coming soon) which uses IQAir’s historic data.
Let’s continue working to raise awareness and make a difference in improving Yerevan’s air quality. Stay informed, and keep pushing for cleaner air for all of us!
