Clearly, annoyance is part of the impact. Annoyance is the most studied impact of environmental noise internationally. It's been studied for many years in Europe and now to some extent in North America. It's most common. For example, the studies we've done in Montreal show that about 20% of people say they're highly annoyed by at least one source of environmental noise.
Annoyance is common; it's present and it does have an impact on the quality of life and health. I think what's important from a public health perspective is to make sure we don't see it as just an annoyance problem. Annoyance is real, and it's problematic, but sleep disturbance is quite separate from annoyance, and I'll explain why.
From a health perspective, the problem with sleep disturbance is not so much annoyance or waking up and realizing an airplane went overhead and it's annoying to wake up; the body's response to noise at night is physiological. We know from many laboratory studies, calibrated studies of sleep disturbance, that you don't need to be waking up to have that impact on long-term cardiovascular health and obesity.
Annoyance is an issue, but sleep disturbance is a separate issue. It's much more tied to the long-term effects of heart health. We need to make sure that we have both of those together. From a regulatory and public health perspective, the strategies for dealing with annoyance are not necessarily the same as those dealing with sleep disturbance, because sleep disturbance is really a nighttime issue for the majority of the population. I think it's important to have both.