Dhaka is one of the most polluted cities in the world, and it is where I live. This Data Studio (formerly Looker Studio) dashboard was made for awareness: it charts Dhaka's air quality from AirNow data for January 1, 2023 to January 31, 2024. It shows a peak AQI of 598 on February 18, 2023, counts of days in each AQI category (133 Unhealthy, 101 Very Unhealthy, 14 Hazardous), and breakdowns by hour of day, month and season.
US AQI and raw PM2.5 concentration, per the dashboard's intro text
Peak and low
Highest AQI 598 on February 18, 2023 at 2:00 AM; lowest 18 on November 16, 2023 at 7:00 PM
Granularity
Hourly readings from every Dhaka location on AirNow, averaged into daily values
Stack
Google Sheets for the calculations, Data Studio for the dashboard
Data
The source is AirNow.gov, the US government's air quality index site, which publishes readings for Dhaka including the US Embassy monitor. Hourly readings from all Dhaka locations available on AirNow for the window were downloaded into Google Sheets.
The US AQI categories, as defined by AirNow: Good 0 to 50, Moderate 51 to 100, Unhealthy for Sensitive Groups 101 to 150, Unhealthy 151 to 200, Very Unhealthy 201 to 300, and Hazardous 301 and higher.
Approach
Daily values. Each day's AQI is the average of its hourly readings.
Calculations in Google Sheets. Days per AQI category, the peak and lowest readings, and the averages by hour of day, month and season are computed in the sheet.
Dashboard. The sheet connects directly to Data Studio as the data source, so the charts read the calculated tables as they are.
What the dashboard shows
Peak and low. The highest AQI recorded in the window is 598, on February 18, 2023 at 2:00 AM, which is in the Hazardous category. The lowest is 18, on November 16, 2023 at 7:00 PM. A line chart plots average, maximum and minimum AQI across the window, with the highest spikes in January to April 2023, the lowest stretch mid-year and a rise again toward December and January.
Days per category. The treemap counts 133 Unhealthy days, 101 Very Unhealthy days, 50 Moderate days and 14 Hazardous days. Those four tiles cover 298 of the 396 days, and no Good tile appears.
By hour. Average AQI is highest at midnight and 1 AM (195) and lowest at 4 PM (147). It falls through the morning, bottoms out in the late afternoon and climbs through the evening.
By month. Average AQI peaks in January (269) and bottoms out in July (94). December (227) and February (225) are next highest after January. The monthly bars aggregate the whole window, so January blends 2023 and 2024.
Seasons. The dashboard describes a winter spike from December to January, relief during the monsoon from June to August, and a rise again from September to November. The month values above follow that pattern.
World comparison. A world map colors countries by AQI on a scale from 4.3 to 229.2.
The dashboard also gives reasons for the night-time peak (temperature inversions and reduced vertical mixing, continuous emissions, flat terrain, calm winds and high humidity) and for the seasonal pattern (rain washing out pollutants in the monsoon, construction and festive activity in autumn). These are explanatory notes on the dashboard, not measurements from the data.
Questions
What was the highest AQI recorded in Dhaka in 2023?
In the AirNow data behind this dashboard, the highest reading is an AQI of 598 on February 18, 2023 at 2:00 AM. Any reading above 300 is in the Hazardous category.
Which month has the worst air quality in Dhaka?
January has the highest average AQI in the dashboard window at 269, followed by December and February. July is the lowest at 94. The window runs from January 2023 to January 2024, so the January figure combines two Januaries.
What time of day is Dhaka's air most polluted?
Averaged over the window, AQI is highest around midnight and 1 AM at 195 and lowest at 4 PM at 147. The dashboard attributes the night-time peak to temperature inversions and continuous emissions.
