Various factors in the environment and outside of your home can be important triggers or causes for the symptoms of asthma and asthma attacks.
It is often assumed that it is better for people with asthma to live in a rural area rather than in an inner city.
However, research has shown that even in the least polluted parts of the UK, such as the Scottish Highlands, the proportion of people with asthma is about the same as that elsewhere.
There is no best place to live for everyone with asthma.
Living somewhere where a person comes into contact with fewer of their triggers is the best idea, and this is why it is doubly important to identify your triggers for asthma.
Some triggers can occur in any part of the country, such as viral infections or cigarette smoke, while others may vary locally, such as air quality or pollen.
In the UK, you can easily check the local levels of air pollution by contacting the Air Pollution Information Service, run by the Department of Environment, Food & Rural Affairs (DeFRA), or on Teletext page 156.
In the U.S and Canada, the Weather Network website has air quality reports for cities in every state and province.
Pollens can blow for many miles but for general details in the UK, contact the Pollen Research Unit. During the summer months, you can look out for regional pollen counts in local media, or on Teletext or television or radio weather forecasts.
For many people the location of their house may be a trigger factor. People whose triggers are linked to damp, such as mould spores or house-dust mite droppings should avoid housing with signs of damp or near overground or underground rivers or canals.
Some people worry that living close to an industrial or agricultural site such as a quarry, power station or chicken farm could be a trigger for their asthma, but published research on effects on local communities from local industry emissions is limited, making it difficult to obtain detailed information.
Most of us spend a large part of our lives in our homes, so the effects of the indoor environment on our health are much more important than the effects of outdoor air pollutants.