Does secondhand smoke affect asthma?

since smoking cause lung cancer, doctors wonder whether it also affects asthma.

the following scatter plot shows the number of smokers in each person’s household compared to the number of asthma attacks they have had:

does the graph have a linear or nonlinear association? is the correlation between the number or smokers and the number of asthma attacks positive, negative or no? what can you conclude from the data shown regarding secondhand smoke’s affect on asthma? explain how you know.