UN Secretary - General Kofi Annan told the assembly that in less than 50 years, the number of people who are over 60 years of age will grow from 600 million to almost 2 billion, outnumbering those under 15 years of age.
इससे फेफड़ों के ऊतक में परिवर्तन आता है जिससे द्रव्य अंदर आने लगता है ।