Hassan city is among three Indian cities with minimum air pollution, according to the latest World Health Organisation (WHO) study on ambient air quality. The study spanned over 1,600 cities in 91 countries.
Of the 123 Indian cities that were covered by the study, Hassan ranked third in terms of least concentration of dust particles in air. The other two cities are Kollam and Pathanamthitta in Kerala.
The WHO conducted the study and prepared a database of ambient air quality, considering the concentration of particulate matter in air. Particulate matter with a diameter of 10 micron (PM10) and 2.5 micron (PM2.5) were considered for the study. The collected daily measurements or data were aggregated into annual mean for the database.
As per the database, in Hassan, the annual mean of PM10 was recorded at 44 μg/m3 (micrograms per cubic metre of air) and PM2.5 at 19 μg/m3.
In Kollam, it was 39 μg/m3 and 17 μg/m3 respectively and in Pathanamthitta, it was 23 μg/m3 and 10 μg/m3 respectively.
The concentration of particulate matter recorded in Pathanamthitta is closer to the recommended level.
Other cities in StateBangalore and Gulbarga were the two other cities in Karnataka that were considered for the study.
Bangalore recorded 103 μg/m3 of PM10 and 45 μg/m3 of PM2.5, while Gulbarga recorded 64 μg/m3 and 28 μg/m3 respectively.
High levels of pollutionNew Delhi with 286 μg/m3 of PM10 and 153 μg/m3 of PM2.5, Gwalior (329 and 144) and Raipur (305 and 134) are among the cities with high levels of pollution owing to high concentration of dust particles.
As per the WHO guidelines, the recommended annual limit of PM10 is 20 μg/m3 (micrograms per cubic metre of air) and for PM2.5 it is 10 μg/m3.
However, none of the Indian cities considered for the database reported concentration of particulate matter within the recommended limit. The organisation collected data of particulate matter because “it is an important indicator of long-term air quality and health risks”. The data was collected “from official national and sub-national reports or institutes or websites reporting measurements of PM10 and PM2.5”, according to the report released by WHO.
The objective of the database, according to the WHO, is to raise awareness and facilitate adequate responses to protect health from the adverse impact of outdoor air pollution. “The aim of this database is not to rank cities or countries”, it said.
Based on the data collected, the WHO concluded that about half of the urban population in the world live in cities that exceed the recommended levels of particulate matter by 2.5 times.
