Despite the rain, Jakarta's air quality remains poor.

Finally, several areas in Jakarta experienced rain on Tuesday night (October 24, 2023). This rainfall was widely welcomed by netizens on social media.

The Meteorology, Climatology, and Geophysics Agency (BMKG) had actually predicted that the Jabodetabek area would experience continuous rain from 10:45 PM WIB on October 24, 2023, to 3:00 AM WIB on October 25, 2023.

"There is a potential for moderate to heavy rain accompanied by lightning or thunder and strong winds," said BMKG via its Twitter account, as quoted by Okezone.com on Tuesday night (October 24, 2023).

On Wednesday afternoon (October 25, 2023), several areas in Jakarta were also observed to be experiencing rain. However, the rainfall did not improve Jakarta's air quality.

Data from the air quality monitoring platform IQAir shows that the daily average air quality, measured using the Air Quality Index (AQI US), reached 156 points on Tuesday (October 24, 2023).

Now, in the latest data on Wednesday (October 25, 2023) at 1:45 PM WIB, Jakarta's air quality has reached 164 points.

For the past two days, Jakarta's air quality has been categorized as unhealthy. The main pollutant is PM2.5, with a concentration of 66.5 µg/m³ (micrograms per cubic meter). This value is 13.3 times higher than the World Health Organization (WHO)'s annual air quality guideline.

The WHO's ideal air quality standard for PM2.5 concentration is between 0 and 5 micrograms per cubic meter.

Even in the monthly trend, Jakarta's air quality is still dominated by the red category, meaning unhealthy. The "best" air quality occurred on October 19, 2023, with a value of 108. However, this value is still considered unhealthy for sensitive groups.

Quoting CNN Indonesia, Poorna Khanna, a researcher in AQI Environmental Management, explained that rain should reduce the most common air pollutants, such as particulate matter, and drastically improve air quality.

She referred to this phenomenon as wet deposition, also known as rainout, wet removal, or washout.

"[This phenomenon] is a natural process that removes matter through atmospheric hydrometeors, such as rain, hail, and snow. It sends and deposits pollutants to the ground," said Poorna, as quoted by CNN Indonesia from the AQI website.

Here is the IQAir index score reference:

* 0-50 points: Good air quality
* 51-100 points: Moderate air quality
* 101-150 points: Unhealthy air quality for sensitive groups
* 151-200 points: Unhealthy air quality
* 201-300 points: Very unhealthy air quality
* >301: Hazardous air quality.

(Also read: [Understanding the Forms of PM2.5 and PM10, the Causes of Air Pollution in Jakarta])