Can Air Quality be Good and Bad at the same time? Let's look at Bogor
Sensors located close together normally display the same Air quality pattern, however, the data acquired by Nafas shows that the Bogor region is separated into two groups. On the same day and at the same hour, the Bogor Timur Area has a healthier AQI than the Bogor Barat Area, as seen in the AQI chart below.
How is this possible? How can two locations that aren’t too far from each other, display a stark difference in air quality?
From our year-to-date observation of Bogor Timur and Bogor Barat, the graph shows that overall air quality in Bogor Timur is roughly 22% better than Bogor Barat. The significant gap concludes that the condition in both areas is not affected by seasonal changes but rather is affected by four possible reasons:
- The healthier side (Bogor Timur) is located near the mountainous area while the unhealthy side (Bogor Barat) is located in the city area. The city area has more traffic and more human activities, which might cause high levels of pollution in that area.
- Since the unhealthy side (Bogor Barat) has a lower elevation compared to the healthier side (Bogor Timur) and the unhealthy side is surrounded by a mountainous area, they tend to hold pollutants like a basin holding water. Although, the wind sometimes helps to push the pollution away. Due to the city’s topography and population density, it supports the creation of a temperature inversion layer* in Bogor Barat. This traps the pollutants near the ground and results in high pollution concentrations from night until morning.
*Do you remember seeing smog/fog during the morning? That is the result of temperature inversion.
Picture 1. Illustration of atmosphere conditions around Bogor during night time.
- The mountainous area is vast and less populated by buildings, cars, and people compared to the city area. Buildings might block or change the direction of the wind, which can cause the wind speed to be lower in the city area compared to the mountainous area. Having a more open area means it will result in the wind being able to carry the pollution better compared to high-density areas.
- Bogor Barat's high proportion of industrial areas has an influence on the air quality in the area. The air quality will worsen as the number of industries increases and vice versa. As a result, Bogor Barat has a higher average air quality than Bogor Timur.
So, what does this air quality disparity teach us? Mainly, that air quality is extremely hyperlocal. This is why Nafas has almost 170 sensors across six cities and we are planning to expand our network even further. Hyperlocality and density of air quality sensors mean more accurate data to help you stay healthy amid a polluted environment.