Dhaka, Bangladesh – Dhaka, the bustling and densely populated capital of Bangladesh, found itself among the world’s most polluted urban centers on Thursday morning, registering a concerning Air Quality Index (AQI) of 162. This reading, recorded at 10:55 am, placed the city in the ‘unhealthy’ category, signaling a significant threat to public health.
The latest AQI report paints a grim picture of the air quality in Dhaka, categorizing it as detrimental to the general population. This situation is not unique to Dhaka, as several other major Asian cities also featured prominently on the same list. Beijing, China, led the rankings with an AQI of 236, followed by Delhi, India, at 198, and Chiang Mai, Thailand, at 181.
Understanding the AQI scale is crucial for residents to gauge the severity of air pollution and its potential impact on their well-being. The scale categorizes air quality as follows:
- 0-50: Good – Air quality is considered satisfactory, and air pollution poses little or no risk.
- 51-100: Moderate – Air quality is generally acceptable. However, there may be a moderate health risk for a very small number of people who are unusually sensitive to air pollution.
- 101-150: Unhealthy for Sensitive Groups – Members of sensitive groups may experience health effects. The general public is less likely to be affected.
- 151-200: Unhealthy – Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects.
- 201-300: Very Unhealthy – Health alert: everyone may experience more serious health effects.
- 301+: Hazardous – Health warnings of emergency conditions. The entire population is more likely to be affected.
The AQI serves as a vital daily public health advisory, providing residents with clear information about the current state of their air and potential health consequences. In Bangladesh, the calculation of the AQI is a comprehensive process that takes into account five key atmospheric pollutants:
- Particulate Matter (PM): This includes both PM10 (particles with a diameter of 10 micrometers or less) and PM2.5 (particles with a diameter of 2.5 micrometers or less). These fine particles are particularly dangerous as they can penetrate deep into the lungs.
- Nitrogen Dioxide (NO2): A gas primarily produced from the burning of fuel.
- Carbon Monoxide (CO): A colorless, odorless gas produced by incomplete combustion of carbon-containing fuels.
- Sulfur Dioxide (SO2): A gas produced by burning fossil fuels, particularly coal and oil.
- Ozone (O3): Ground-level ozone is a major component of smog.
Dhaka has a long-standing and well-documented struggle with persistent air pollution. The city’s air quality typically experiences a significant deterioration during the cooler, drier winter months. Conversely, the arrival of the monsoon season, with its regular rainfall, usually brings a welcome improvement to the air quality, washing away pollutants from the atmosphere.
The global implications of air pollution are stark. The World Health Organization (WHO) estimates that air pollution is responsible for an alarming number of deaths worldwide each year, with approximately seven million premature deaths attributed to its effects. The primary health conditions linked to air pollution exposure include stroke, heart disease, chronic obstructive pulmonary disease (COPD), lung cancer, and acute respiratory infections, highlighting the urgent need for global action and localized mitigation strategies.
