Dhaka's toxic air raises health risks in winter amid pandemic

Dhakaites breathed a bit easy after the nationwide coronavirus-induced lockdown dragged down the level of air pollution during the early months of last year, but concerns over the worsening air quality in the capital resurfaced with the onset of winter.

In the early days of the coronavirus infection in the country last year, all kinds of economic activities including vehicles and factories ground to a halt.

As the dry season wears on, with the economy restarting in full swing, experts believe the health risks posed by the poor air quality are as high as ever.

Its consequences, particularly in the midst of a pandemic, could be dire as exposure to air pollutants increases the risk of respiratory infections while weakening the immune system, they warned.

Data from the health directorate showed that between November and mid-January, around half a million people in Bangladesh have been afflicted with respiratory infections.

Research by the Environment and Social Development Organization (ESDO) found that air pollution not only poses a health risk but also has an adverse effect on the environment and the economy.

According to meteorological organisations, the toxicity levels in Dhaka's air are currently on the rise. Apart from Dhaka, the air quality in different parts of the country has been deteriorating and exceeding the danger limit in recent times.

The air quality rating is based on the amount of fine particulate matter (PM-10) and fine dust (PM2.5) that are in the atmosphere, which are measured in micrograms (parts per million-ppm) per cubic meter.

A layer of dust blankets a street at Postogola in Dhaka. Photo: Mahmud Zaman Ovi

In addition to PM2.5 and PM10, the level of air pollution caused by sulfur dioxide, carbon monoxide, nitrogen dioxide and ground-level ozone is also taken into account when determining the Air Quality Index (AQI) score. The AQI value is proportional to the amount of air pollution in a particular area.

For context, an Air Quality Index or AQI of 0-50 represents ‘good’ quality of air while 51-100 is considered ‘moderate’ and 101-150 is deemed ‘dangerous’. But the air quality is classified as ‘unhealthy’ when the PM reaches 150-200, ‘very unhealthy’ at 201-300 and ‘hazardous’ at 301-500.

When the AQI rating reaches hazardous levels, it could cause serious health problems for the entire population, leading to the issuance of health warnings.

According to a recent study by ESDO, Bangladesh was the second-most polluted country in the world in terms of air pollution in the 11-month air quality index last year while Dhaka was fourth among cities.

Dhaka regularly ranks highly on Swiss-based IQ AirVisual's list of the most polluted cities in the world.

The organisation's data showed the air in Dhaka was very unhealthy and dangerous on as many as 18 days this month. The highest level of air pollution was recorded on Jan 19, when the AQI was 363. The AQI in Dhaka soared up to 603 around 8 am that day.

According to the US Embassy, the AQI in Dhaka rose to 642 on the same day. The embassy's air monitoring data also showed that the pollution level was very unhealthy and dangerous on 26 days in December.

The toxicity of Dhaka's air is putting a severe strain on public health, said Dr Biswas Akhtar Hossain of Northern International Medical College.

A thick layer of dust covers the air of Road No. 27 in Dhaka’s Dhanmondi as sewerage repair work drags on. Photo: Mahmud Zaman Ovi

Most of the patients they receive in the winter suffer from asthma, COPD and lung infection, said the former professor of respiratory medicine in Dhaka Medical College. Children and elderly people are more vulnerable in the season.

“Environment turns hazardous when fog adds up to air pollution. Increase of diseases like asthma, bronchitis, or COPD may lead to secondary infection and end up in pneumonia.”

Dhaka air never remains breathable, says public health expert Lenin Chowdhury.

“When do we call the air pollution level hazardous? When we fall sick after breathing in that air, when it enhances the risks to life or becomes hazardous to human health. The air quality has been constantly low, at an unhealthy level after the winter set in. At times, it becomes hazardous. It means we are inhaling such polluted air in Dhaka that our lungs and respiratory system are affected,” he said.

The physician explained how air pollution is affecting the people in Dhaka.

“PM 2.5 enters the human blood and reaches the liver, kidney spleen and other organs while affecting the hormones. Therefore, it causes different diseases.”

“Polluted air increases respiratory diseases and on the other hand, it causes a rise in the number of diseases like tuberculosis. Those suffering from respiratory tract allergy get asthma, while those with sensitive respiratory systems develop respiratory distress.

"It causes more illnesses like pneumonia, tuberculosis, sore throat; in many cases it leads to headache or nausea. Sometimes people get faster heartbeats.”

People already suffer from severe cold in winter and the diseases add to their woes, he said. “We begin to receive patients with respiratory distress just from the next day air pollution increases,” he said.

According to the Directorate of Health Services, the number of asthma patients rose to 78,806 in 2019 from 3,326 in 2015. The death toll of asthma patients also had a rise to 588 from 56.

Air pollution causes infertility and other damages to both men and women's health, said Lenin Chowdhury.

“Air pollution has both immediate and long term effects (on people’s health). Respiratory distress, sneezing, cough begin immediately. Pneumonia also manifests in a few days. But diseases like lung cancer, kidney or spleen ailments take time to appear,” he said.

Not only humans, air pollution affects the entire ecosystem, believes Lenin, an environment activist.

“Air pollution leaves a layer of dust on the trees which prevents the photosynthesis and destroys the balance of oxygen and carbon dioxide. This becomes injurious to animal health. Polluted air gets infused in water and hampers the health of the living creatures there. We’ll become a sick nation if this goes on,” said Chowdhury, joint general secretary of Paribesh Bachao Andolon.

No regulation in the construction work, brickfields and,  lack of control over vehicles causing air pollution,  unplanned factories along with authorities not spraying water are the reasons behind the rise in air pollution, he said.

“Bangladesh Meteorological Department and Department of Environment should issue warnings for the people on the days the air quality is at an unhealthy or hazardous level. It will enable people to remain indoors and not head out unless it is much needed. They may wear a mask while going out. Issuing an air pollution index will  be helpful for people.”

People should be more aware to evade the ill effects of air pollution, said Biswas Akhter Hossain, vice president of Asthma Association of Bangladesh.

“People should wear warm clothes so that the chilled wind can’t enter through the nose or mouth. They should avoid going out in the fog. Consumption of nutritious food enriched with protein, vitamin, and minerals is a must. Wearing a mask is necessary too. Those who are aware (of the situation ) wear a mask. Many of my patients were able to prevent falling sick in the winter,” said Hossain, who is also a senior vice president of the Chest and Heart Association of Bangladesh.

Severe dust pollution adds to commuters' woes on the ruptured Mariner's Road in Chattogram's Firingi Bazar area. Dust pollution increases in winter. Photo: Suman Babu

Outside factors are far more responsible for the air pollution in Dhaka, believes Ziaul Haque, the director at Department of Environment, Dhaka Division.

“Polluted air from India enters Bangladesh through the north-western and western part. This is why we see a rise in air pollution,” he said.

“A cloud of pollution enters Bangladesh and proceeds to the Bay of Bengal through Dhaka and Chattogram. It’s a huge layer of pollution.”

Changing seasons and transborder movement of air are the primary reason for air pollution, according to a report of the Environment and Social Development Organization-ESDO.

The air from the transborder areas has the highest pollutant in it and it blows to the north due to the Indian belt reaching Dhaka, Cumilla and Mymensingh.

Air pollution rises from November to January as the airflow remains low, said Ziaul.

The authorities have focused on reducing the construction work in Dhaka, Haque said about the government’s initiatives to control the air pollution. “We’ll increase water spraying on the construction sites,” he said.

“We’re also conducting drives in the brickfields and have sealed around 50 brick kilns from December to January.”

Though they have not been successful in curbing the air pollution caused by transports, the authorities are consulting the BRTA on the issue, said Ziaul.