I wasn't sure about this question, so I asked a friend of mine who is studying to be a doctor. She told me that you are right, the difference could be either you or the type of cigarette. You could eventually find out what types of cigarettes are more likely to bring on an attack and avoid them and the people who smoke them.

Just a guess, but different manufactures put different chemicals into cigarettes.You could very easily be sensitive to one of the chemicals that they use...or gets changed after burning. You should watch what brand effects you. You may never know which chemical it is, since the chemical make-up of the cigarettes is considered propitiatory information (ie. they won't release it--company secret), but this may change since a lot of lawsuits are being filed against the Cigarette industry. Keep your eyes open and maybe somebody will publish.

Good question! You noticed a pattern and came up with 2 hypotheses to explain it. Let's start with what causes asthma. Asthma can have different causes, such as allergies, infection, or an irritant like smog or cigarette smoke. What happens is that the bronchioles (the tubes that carry air to the deepest part of the lungs) get smaller. This is probably a way for the lungs to protect themselves from whatever nasty things are around. Whether you have an asthma attack at a particular time may depend on what's going on in your body. All cigarette smoke is bad in the same way. It contains "tar" and nicotine along with other chemicals caused by burning the tobacco, paper, glue, and the pesticides and fertilizers that were sprayed on the tobacco as it grew.

Given that smoking has been proven to be so bad, why do you think people still smoke?

This site has more information on the link between smoking and asthma:
http://asthma.miningco.com/library/weekly/aa110998.htm

This site is pretty technical, but with your teacher's help, you should be able to understand it all:
http://www.health.gov.au/nhmrc/advice/nhmrc/chap3/sec2.htm#asthma

In addition to the fact that different cigarettes have different chemicals in them that you may be more sensitive to, you could have a changing sensitivity to all cigarettes in general. For example, some days your asthma may be more easily triggered in general, not just by cigarettes and other days your asthma is not so easily triggered. This could be due to fluctuations in hormones that your body produces naturally or environmental factors that you are unaware of. Environmental factors may include things you are allergic to, pollens, dust, molds, etc. these allergens will commonly cause/aggravate asthma.