Air pollution: This May worst in eight years

Dhaka’s air pollution in May of the current year has surpassed air pollution in May of the past seven years. The average pollution level this May has increased by 23 per cent compared to previous years.

And compared to last year (2022), it has risen by more than four per cent. The number of days city residents have spent in this unhealthy air last May is higher than that of the last seven years.

Stamford University’s Centre for Atmospheric Pollution Studies (CAPS) has presented these figures after analysing air pollution of the last eight years. CAPS researchers have analysed Air Quality Index (AQI) from 2016 to 2023, received from the US Embassy in Bangladesh.

AQI score of 0 to 50 is ‘good’ quality air. When it goes from 51 to 100 it’s considered ‘moderate’ or ‘acceptable’ level of air. The score from 101 to 150 is considered ‘unhealthy for sensitive groups’ and if the score is between 151 and 200, it is considered ‘unhealthy’.

When the score goes from 201 to 300 it is called ‘very unhealthy’ while, the score beyond 301 is dubbed ‘hazardous’.

According to CAPS research, average air quality in May of the last seven years was 122.29. Dhaka’s average AQI in May of 2016 was 123. The average quality kept fluctuating in the following years. It was 114 in 2021.

Then in 2022, the air quality index rose to 144 compared to past. And in May of the current year, 2023, the air quality index has increased even more taking it to 150.36.

CAPS chairman professor Ahmad Kamruzzaman Majumder told Prothom Alo, “Not just in May, we have found that air pollution was way higher this April as well compared to the last seven years."

"Apart from the dry months, pollution in other months is also on the rise now. It’s not pleasant for the city dwellers or the public health," he added.

The air in Dhaka was unhealthy for 16 days in May this year. This was 13 days in May 2022, while in the May before that (2021) it was just five days.

The air was unhealthy for 46 days in May of the last eight years. Of them, 16 days were in this may alone. And the air quality has been good for only one day this month.

Regarding the data provided by CAPS, deputy director of the department of environment Mohammad Abdul Motalib said that the sub-continental air flow has a contribution to Bangladesh’s air pollution.

There was such an air flow just in this April. Do those issues come up in CAPS’s research? Without taking these issues into consideration, talking about pollution alone isn’t scientific.

The air flow, Abdul Motalib talked about has also been mentioned in World Bank’s research to have an impact on Dhaka’s air pollution. That report titled ‘Striving for Clean Air: Air Pollution and Public Health in South Asia’ was published in March this year.

It had been stated there that the same clouds pass above four South Asian countries including Bangladesh. Polluted air is also accumulating inside these clouds, which is later spreading across these countries.

Nine of the top ten countries around the world with the worst polluted air are located in South Asia. And, Dhaka is notable among them.

As much as 30 per cent of Dhaka’s polluted air actually comes from India. However, 40 per cent of the polluted air enters Dhaka from other cities of the country.

Concerning the research CAPS chairman Ahmad Kamruzzaman Majumder told Prothom Alo that the intrusion of sub-continental polluted air is of course a considerable issue.

But, the effects of that are basically existent during the dry season or towards December till March.

Then there’s not much pollution in April and May. So, in case of Dhaka it’s the local sources of pollution that work as major factors. These includes fume of old vehicles, dust from construction work as well as the smoke from brick kiln and factories.

According to the records of air quality research laboratory at the chemistry department of Dhaka University, dust and smoke have a 50 per cent contribution to the air pollution in Dhaka.

Construction work amid mismanagement and polluted fume of old vehicles are two major source of this dust. Meanwhile, 40 per cent of the pollution is caused from smoke from organic items such as straw, wood and husks alongside fine particles.

Professor of the chemistry department at Dhaka University Abdus Salam told Prothom Alo, “The impact of sub-continental air flow on Dhaka’s pollution has to be taken into consideration. There has been less rain in April and May this year.”

“So, that air flow continued in these two months as well. However, the local sources do play a major role here. These must be controlled, but no such effort can be noticed,” he added.