Hazards of air pollution

Shahiduzzaman Khan   | Published: May 11, 2019 22:13:40

Bangladesh's capital ranks fourth worst in the Air Quality Index (AQI), according to a report published in the media late last week. Dhaka had a score of 165 at 10:44am, indicating harmful air quality.

India's Delhi, Pakistan's Lahore and Nepal's Kathmundu occupied the top three spots respectively. The AQI, an index for reporting daily air quality, tells people how clean or polluted the air of a certain city is, and what associated health effects might cause them.

A numerical value between 151 and 200 indicates that everyone may begin to experience health effects. Members of sensitive groups may experience more serious health effects.

There is no denying that air pollution has reached menacing proportions in the city. Urban air in the city is thick with fumes; water either in the rivers, ponds or tube-wells is polluted. Unchecked dumping of waste, a lot of it toxic, and noxious emissions from vehicles and pesticides used in farmlands are the main causes.

Although the city fared well in terms of reducing pollution, the situation is still alarming, posing serious health hazards for city dwellers. Things get worse in dry season as air, thick with particulates, becomes a prevalent cause of chest and respiratory diseases.

According to the Department of Environment (DoE), the density of airborne particulate matter (PM) has reached 247 micrograms per cubic metre (mcm) in Dhaka which is nearly five times the acceptable level of 50 PM per mcm set by the National Ambient Air Quality Standard (NAAQS) of Bangladesh.

Airborne particulates are considered more harmful when they are 10 micrometres or smaller in diameter and in Dhaka the density of PM which is 2.5 micrometers or smaller has been found to be 9.0 times higher than the NAAQS' recommendation. Ambient air in the city becomes extremely polluted between October and March every year when rain is scarce and when thousands of brick kilns become operational, burning used automobile and rickshaw tyres, low grade coal and in many cases fuel-wood.

World Health Organisation's (WHO) air quality guidelines, however, recommend a maximum acceptable PM level of 20mcm compared to Bangladesh's standard of 50. Cities with 70mcm are considered highly polluted. Airborne lead is the worst of the harmful PMs.

Although there is no definite study, doctors suggest exposure to such a volume of air pollution may cause premature deaths and also various diseases including pulmonary, respiratory and neurological illnesses. Air pollution has also an adverse effect on all other life forms including plants.

Cost of maintaining building structures in the urban areas also rises significantly due to such air pollution. The number of patients with chest and respiratory diseases in the hospitals and clinics is on the rise.

If this trend of air pollution continues, those living in Dhaka city will become exposed to ailments stated above and also other complications. The mental faculty of children will be adversely affected by lead pollution, which can also affect the central nervous system and cause renal damage and hypertension.

In addition to brick kilns, old buses, fleets of trucks and thousands of other poorly serviced vehicles contribute highly to the pollution. Moreover, dust from roads and construction sites and toxic fumes from industrial sites turn the air quality scenario even worse.

Industrial wastes are responsible for 60 per cent of the surface water pollution in and around Dhaka city while domestic wastes account for rest of the pollution.

More than 0.35 million motor vehicles ply the roads in Dhaka. Diesel-run vehicles account for more than 80 per cent of the air pollution as most of them fail to comply with the emission standard. According to WHO guidelines, lead level in blood above 10 microgram per decilitre is considered lead poisoning.

A recent survey found lead concentration in urban children to be 5.8 to 21.6 microgram per decilitre and urban slum children's lead level ranged from 9.6 to 38.9 microgram per decilitre, three times the acceptable level.

Sadly enough, laws exist to book a polluter, but law enforcers shy away from using the laws in most cases because of unholy nexus with the vehicle drivers. In most cases, polluting vehicles drive away emitting noxious fumes in the presence of the law enforcement personnel without being held up or booked. Old and dilapidated vehicles disappear from the roads during special drives by the law enforcers only to return after the drive comes to an end.

It may be mentioned here that New Delhi in an attempt to reduce air pollution prohibited initially 20 year old vehicles from plying the city streets in late 1990s. They started phasing out 17 year old vehicles from the end of 1998. It was followed by elimination of 15 year old vehicles in 1999.

In the past, attempts to prohibit plying of old vehicles in Dhaka city streets failed either for political reasons or in the face of resistance by transport owners and their employees. But if the neighbouring countries can improve air quality of their cities by banning use of old vehicles and also relocating some of their polluting industries, authorities in Bangladesh can also do the same.

It is thus time to phase out old and black smoke emitting vehicles from city roads as our right to live in a healthy environment largely depends on it. Good governance helped curb air pollution in cities like Bangkok, Kolkata, Kathmandu and Lahore while weak administration caused the increase of air pollution in Dhaka and Karachi.

Indeed, Bangladesh is one of the few countries that face extreme hazards due to environmental degradation and resource depletion. The degradation of the environment has been highlighted in various forums because of its universal potential for chaos and disorder. Environmental problems faced by Bangladesh are far too many though largely caused by factors, which are teleological because of its geographical position.

The ecological hazards of pollution and resource depletion pose a potentially catastrophic threat to Bangladesh. The problem should be high on the agenda of the government as well as political parties. One hopes that the issue will get the priority it deserves.

The government should, in the circumstances, take the environmental threats seriously, and create public awareness and undertake action-oriented programmes.        


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