Welcome  to  the  public  health  moment from  the  University  of  Minnesota. The  numbers  of  children  with  asthma  is  on  the  increase, but  health  professionals  cannot  say  for sure  why  Ian  Greaves, a  professor  of  Environmental  Health  Sciences  at the  University  of  Minnesota,  has  some  insights. Well,  there  are  a  number  of  theories, but  right  now  the  most  appealing  one seems  to  be  what's  called  a  hygiene  hypothesis. And  that  is  that  early  in childhood  when  we  have  our  respiratory  infections, that  seems  to  convey  some  degree  of  prevention  of  asthma. But  because  we've  immunized  children  so  much, they  no  longer  have  as  many  of  those  infections. And  as  they  get  older, they  seem  to  develop  allergies  at  a  higher  rate. Grief  says  that  there  is an  increasing  globalization  of  allergens, including  an  increase  in  indoor  air  pollution. What  can  parents  do  to  protect their  children  from  indoor  air  pollutants? To  the  extent  that  we  can  reduce house  dust  by  having  less  carpeting, more  wooden  floors,  vacuuming, while  the  susceptible  individual, the  child,  is  out  of  the  home. Air  filters  on  our  furnaces  and  air  conditioning  systems, all  of  these  are  ways  to  reduce  the  amount  of  dust, keeping  down  the  cock  roaches  in  the  home. And  also  choosing  products  that  have low  off  gassing  of  hazardous  materials  like  solvents. For  the  public  health  moment,  I'm  John  Finnegan.