Showing posts with label hazardous. Show all posts
Showing posts with label hazardous. Show all posts

Sunday, January 12, 2020

Smoke in Sydney crosses 11 times the “hazardous” level


Australia's deadly wildfires are showing no signs of stopping
Earlier in December, the smoke was so bad in Sydney that air quality measured 11 times the “hazardous” level.

Dre K K Aggarwal
President CMAAO, HCFI and Past National President IMA

Australia is facing the worst wildfires of the decade with large swathes of the country devastated since the fire season began in late July.

A total of 27 deaths and in the state of New South Wales alone, more than 2,000 homes have been destroyed or damaged.

State and federal authorities are struggling to contain the massive blazes.

Persistent heat and drought, and climate change is making natural disasters go from bad to worse.

There have been fires in every Australian state, but New South Wales has been hardest hit.

Blazes have torn through bushland, wooded areas, and national parks like the Blue Mountains. Some of Australia's largest cities have also been affected, including Melbourne and Sydney.

In Australian summer, with hot, dry weather makes it easy for blazes to start and spread. Natural causes are to blame most of the time, like lightning strikes in drought-affected forests. Dry lightning was responsible for starting a number of fires in Victoria's East Gippsland region in late December, which then traveled more than 20 kilometers in just five hours.

About half a billion animals have been affected by the fires across NSW, with millions likely dead -- and that's a conservative estimate. That number of total animals affected could be as high as one billion nationwide.

The figures for NSW include birds, reptiles, and mammals, except bats. It also excludes insects and frogs. [Excerpts from CNN News]


Friday, December 28, 2018

Winter pollution



Air pollution is here to stay ….it’s not just limited to a particular time of the year, but persists all through the year now. According to the WHO, in 2016, India had 14 out of world's 20 most polluted cities in terms of PM2.5 levels; Kanpur topping the list and New Delhi taking the sixth place.

Air quality particularly deteriorates during the winter season and drops to the “severe” or “hazardous” categories.

Pollution levels are increased during winters due to a combination of atmospheric (metereological) conditions and local pollution (emissions of air pollutants).

Generally, air is warmer near the earth surface and gets colder higher up as the altitude increases. During winters, this state is reversed i.e. the temperature is colder near the surface and the air is warmer higher in the atmosphere. 

This phenomenon is called “winter inversion” and is the reason why pollution levels increase during winters, especially in areas like Delhi where air pollutant levels are already higher. This warm air above the cold air acts like a lid and traps the pollutants and does not let them escape into the atmosphere. 

The effects of inversion are stronger at night, which is why air quality worsens overnight. This is also why people are asked to avoid morning walks especially during winters due to exposure to higher concentrations of pollutants at that time.

In summers, the air in the lower part of the atmosphere is warmer and lighter; so, it can rise up and carry pollutants away from the ground and mixes them with cleaner air in the upper layers of the atmosphere (”vertical mixing”).  

Another reason for high pollution levels during winters is a decrease in wind speed, which further slows down the dispersal of pollutants. The pollutants therefore remain close to the surface and worsen the air quality. The ‘trough like topography’ in North India, due to hills and mountain ranges coupled with stagnant air during winters also traps the toxic air over a large part of the country.



Dr KK Aggarwal
Padma Shri Awardee
President Elect Confederation of Medical Associations in Asia and Oceania   (CMAAO)
Group Editor-in-Chief IJCP Publications
President Heart Care Foundation of India
Immediate Past National President IMA