Air pollution

Published:  03:15 AM, 22 November 2020

A new worry for COVID patients

Mishuk Raihan, a resident of Dhaka's Shantinagar, had recovered from the COVID-19 illness about two months ago. He still has a cough as his lungs are yet to regain their full capacity. Doctors advised him to be on guard against the cold in winter and stay away from dust.Raihan and many others, who have recovered from COVID-19, or have underlying respiratory complications will have to be extra-cautious in winter as experts worry that air pollution in Dhaka will be a major setback to combating the novel coronavirus in cold and dry weather. Unhygienic conditions in the city are likely to complicate respiratory issues further.

The experts say breathing unhealthy air damages the lungs and contracting COVID-19 under such conditions could raise the odds of dying from coronavirus infections. Proper coronavirus testing during winter is crucial for treatment, as COVID-19 symptoms are similar to those caused by cold weather, reports

A suspension of the public transport system and a lockdown that slowed construction work lowered dust levels in the city's air for months. The lifting of the curbs, however, led to a gradual rise of the harmful elements in the air again. With the advent of winter, air pollution coupled with low humidity has now reached worrying levels. The air quality of Dhaka and the rest of the country has been declining over the last two weeks, reaching hazardous degrees in some regions.

The quality of air depends on the amount of small floating dust particles (particulate matter or PM 10) and fine particles (PM 2.5) in it, measured in micrograms per cubic metre and parts per million or ppm units.The Air Quality Index is measured on particulate matter (PM2.5 and PM10), Ozone (O3), Nitrogen Dioxide (NO2), Sulfur Dioxide (SO2) and Carbon Monoxide (CO) emissions. The higher the AQI value becomes, the riskier the air quality gets.

AQI ranging between 0 and 50 means good air quality while 51-100 means moderate air quality. AQI 101-150 is unhealthy for sensitive groups, such as children, elderly and asthma patients, while 151-200 is unhealthy for all. When the AQI is between 201 and 300, it is considered very unhealthy and beyond 300 is a hazardous level.

Dhaka averaged 284 on the AQI on Nov 18, peaking to 294, according to data from the Department of Environment. Narayanganj, located beside Dhaka, recorded a hazardous level of 353 on the AQI the same day.According to Swiss air quality technology company IQAir, Dhaka recorded satisfactory levels, or below 100, in six of the last 11 days of October. But dust particles began rising in November, registering more than 150 on the AQI in the first 10 days of the month and peaking to 225 on Nov 4.

The air quality is at its worst from evening to morning in cities. In Dhaka, the fluctuations can see air quality dropping from unhealthy to hazardous levels in the period.There is little change to air quality at this time, which often puts Dhaka at the top of the list of cities with most polluted air in the world.The Department of Environment has warned that the situation would get worse in the days to come.

"In November, the AQI averaged between 180 and 200, but the situation would get even worse in the weeks to follow. Usually, the air quality is at its worst in November and December," said Ziaul Haque, the director of the department's Air Quality Management Division.He said the sources of air pollution get more active during winter. Due to a low wind speed, the layer of polluted air takes time to move away, and the air never clears out until rain arrives. That is what worries the experts.

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