Karachi ranked among the world's most polluted cities

KARACHI: The metropolis ranked atop in pollution in Pakistan while at 5th on a global Air Quality Index (AQI) on Tuesday morning, placed among the world’s most polluted cities, ARY News reported.

According to recent reading of the Air Quality Index Karachi was ranked 5th with 209 particulate matter at noon.

AQI as high as 151-200 is considered unhealthy, while an AQI between 201 to 300 is more harmful and an AQI over 300 is dubbed extremely hazardous.

Pakistan Meteorological Department (PMD) had earlier said in the morning that dusty winds blowing in the city from the northeast and particulate matter in the air is above the hygienic level at 190.

Particulate matter in Lahore recorded 154, Peshawar 173, Indian capital New Delhi 175, Kolkata 174 and Dhaka 184.

According to experts, the air is heavier in the winter as compared to summer, causing poisonous particles in the atmosphere to move downwards and making the atmosphere polluted. As a result, a layer of polluted particles, including large amounts of carbon and smoke, covers the city.

The smoke produced by factories and by burning coal, garbage, oil or tyres enters the atmosphere and the effects of this appear at the onset of winter and remain till the season’s end, experts said.

Thus, air pollution reaches extremely dangerous levels, severely compromising the air quality.

Although southwestern winds blowing from the sea may work as a filter for the air in the city, these winds remain mostly suspended during winter, experts said.

They noted that winds blowing from the northeast increase the concentration of hidden polluted particles, and a healthy atmosphere in such a situation is subject to rainfall, which washes off all polluted particles.

The AQI is calculated based on five categories of pollution: ground-level ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide.