Experts say people should eat no more than 70g a day of red and processed meat for good health with processed meat possibly making asthma symptoms worse.
meat
A study carried out in France ‘journal Thorax’ believe the preservative nitrite used in sausages, ham and salami may make these symptoms worse. The survey looked specifically at asthma symptoms – breathlessness, wheeze, chest tightness – and intake of cured meat: a single portion was two slices of ham, one sausage or two slices of salami.

“People who said they consumed more than four portions a week – eight slices of ham or four sausages, for example – had the biggest deterioration of their asthma by the end of the study.”

 
The experts stress that their work cannot prove diet is definitely to blame. There are lots of factors in a person’s life that can make their asthma worse.
references: bbcnews.co.uk