Breathless? Blame it on temperature, trapped pollutants
Neha Madaan,TNN | Dec 12, 2013, 03.56 AM IST PUNE: People living in Hadapsar, Katraj, Bhosariand Shivajinagar may be more susceptible to respiratory infections such as asthma and chronic bronchitis because the chill the city is currently experiencing has pushed air pollution levels to a new high in these places.
The city continued to shiver with the minimum temperature at 7.4 degrees celsius on Tuesday. The levels of particulate matter less than or equal to 10 micrometer (PM10) has crossed the maximum permissible limits by more than 100% in Hadapsar, Katraj, Bhosari, Shivajinagar.
Data from the Indian Institute of Tropical Meteorology (IITM) shows that on December 10, air quality of Pune had reached 'very low' levels, with some stations recording PM10 levels beyond 200 ug/m3. The maximum permissible limit is 100 ug/m3. There was a marked difference in the air quality which remained good to moderate on November 30 and on December 10. The minimum temperature on November 30 was close to 22 degrees Celsius and only Shivajinagar, Alandi and Hadapsar recorded PM10 levels a little above the permissible limits.
On December 10, all locations--Pashan, Shivajinagar, airport area, Hadapsar, Alandi, Katraj, Bhosari, Nigdi and Manjari had PM10 levels hitting the roof, ranging from 103 ug/m3 to 221 ug/m3.
The minimum temperature on December 10 was considerably lower, with the city experiencing around 9 degrees celsius as per IITM data. "Hence, the increase in pollution levels," said Gufran Beig, IITM chief scientist and project director of System of Air Quality Forecasting and Research (SAFAR).
As the temperature drops, the boundary layer or the cape of the surface or the upper boundary of the local environment reduces in height. "It is this boundary layer which traps the pollutants emitted from the surface and near the surface, preventing them from mixing upward and diluting into the atmosphere. On November 30, the boundary layer was 1.5 km. However, within 10 days, from November 30 to December 10, the minimum temperature has gone down to around 9 degrees celsius and the boundary layer has reduced to around 700 meters," said Beig.
Though the same amount of man-made pollutants are being emitted in Pune in winter, weather conditions and cooling have brought the boundary layer down, confining the pollutants to this limited envelope. Air pollution levels have thus been ranging from moderate to very poor in Pune, Beig added. On December 7, the minimum temperature was between 12 to 13 degrees celsius and PM 10 levels crossed the 100 ug/m3 mark in all areas, shooting to 156 ug/m3 in Shivajinagar, and 168 ug/m3 in Hadapsar.
When the minimum temperature in the city was around 10 degrees celsius on December 8, PM10 levels in Shivajinagar were close to 160 ug/m3, while PM 2.5 here was around 90 ug/m3, which means 'poor' air quality, said Beig. The maximum permissible limit for PM 2.5 is 60 ug/m3.
On December 9, with Pune's temperature falling to around 9 degrees celsius, most polluted areas were Katraj (with PM10 levels close to 163 ug/m3, and PM 2.5 levels around 96 ug/m3), Hadapsar (with PM10 levels close to 220 ug/m3, and PM2.5 levels around 98 ug/m3) and Bhosari (with PM10 levels close to 161 ug/m3).
Forecast of pollution levels by IITM scientists, using the SAFAR model, revealed that the current levels of PM10 and PM2.5 are likely to remain almost at the same level for the next two-three days with temperature dropping further.
The term Particulate Matter (PM) includes both solid particles and liquid droplets found in air. Many man-made and natural sources emit PM emissions directly or emit other pollutants that react in the atmosphere to form PM. These solid and liquid particles come in a wide range of sizes.
PM has two sets of cautionary statements, which correspond to the two sizes of PM that are measured:
Particles up to 2.5 micrometers in diameter (PM 2.5)
Particles up to 10 micrometers in diameter (PM 10) Health Effects:
Health effects have been associated with exposures to PM over both short (such as a day) and longer periods (a year or more).
When exposed to even small levels of PM, people with existing heart or lung diseases-such as asthma, chronic obstructive pulmonary disease, congestive heart disease, or ischemic heart disease-are at increased risk of premature death and or admission to hospitals or emergency rooms.
The elderly are very sensitive to PM exposure. They are at increased risk of admission to hospitals or emergency rooms and premature death from heart or lung diseases.
Children and people with existing lung disease may not be able to breathe as deeply or vigorously as they normally would, and they may experience symptoms such as coughing and shortness of breath when exposed to levels of PM.
PM can increase the susceptibility to respiratory infections and can aggravate existing respiratory diseases, such as asthma and chronic bronchitis, causing more use of medication and more doctor visits.