Michael Brauer, Professor of Public Health at the University of British Columbia and renowned expert on the impact of air pollution on health, speaks to delhiair.org about the effects of both short-term and long-term exposure to air pollution on our bodies.
Ambient Air Pollution and Health
How does air pollution affect my health?
There are two main ways that air pollution affects health. First, over a short time period (several hours) exposure to high levels of air pollution can cause immediate symptoms that range from difficulty breathing, coughing and chest tightness to severe worsening of asthma or chronic lung disease or even triggering a heart attack or a stroke. The more severe affects are typically only felt by people with some pre-existing heart or lung disease. Second, long term (months to years) exposure to air pollution contributes to the development of many of the common chronic diseases such as heart disease, bronchitis and emphysema and lung cancer. We also know that air pollution can lead to a worsening of respiratory infections such as pneumonia or even ear infections. Air pollution makes it harder for the body to fight these infections. Recent research also shows that exposure to air pollution during pregnancy leads to lower birthweight babies and a greater likelihood of a premature birth.
What kinds of symptoms might I feel from being exposed to air pollution on a hazardous air day?
People who are in good overall health generally will not feel any symptoms at all or perhaps mild symptoms such as a cough or a feeling of tightness in the chest. We are most concerned with people who already have heart or lung disease or infants – especially those who might already have a respiratory infection. People who are on medication for heart or lung disease should be sure to use their regular medication and may need to increase the amount of “reliever” medication on days when air pollution is most severe.
Does air pollution affect everyone the same way? (What about babies, kids and older people? People with compromised immune systems?)
Most of the severe immediate effects of air pollution are experienced by people who have heart or lung disease and the air pollution will tend to make their disease worse. Those who have diabetes are also more likely to be impacted. In general the very old and very young will also experience more effects. People with a respiratory infection – especially infants – are also more likely to be affected. We also are concerned about pregnant women – while they may not experience immediate impacts, exposure to air pollution can negatively affect the developing fetus. One way that people can protect against the harmful effects of air pollution is to maintain their overall level of health through diet, exercise, avoiding smoking, reducing stress and moderating alcohol consumption.
Can a person’s body become accustomed to air pollution so that it doesn’t affect their health?
There is some evidence that people who are regularly exposed to air pollution may experience fewer of the immediate symptoms, but the story is not all positive as this lack of an immediate response seems to mean that the more chronic affects of air pollution have started to kick in. In some ways what happens after repeated exposure is that the body has given up and does not try to protect itself against the pollution – but since the pollution is still present it begins to have more long term impacts.
If I don’t feel any symptoms, is air pollution still bad for me?
Unfortunately air pollution can still be bad for your health even if you don’t feel symptoms. We are most concerned with the role that air pollution plays in the slow development of the chronic diseases of aging that are common – heart disease, lung disease and also lung cancer.
I have heard that breathing air pollution on a hazardous day is like smoking cigarettes for your health. Is that true?
The effects of air pollution and smoking are remarkably similar – the main difference is that we cannot choose to avoid air pollution whereas we can choose to smoke. For those who smoke the effects tend to be more severe than the effects of air pollution, but the difference is not all that large.
Can my body recover from the affects of bad air once I am in a clean-air environment?
Certainly the symptoms that arise from short-term exposure are reversible and we tend to recover from these immediate effects quite quickly, especially for those who are otherwise in good health. For people with pre-existing heart or lung disease the recovery may take longer or may not occur at all.
If so, how long would / could that take once I am in clean air?
For healthy individuals recovery from symptoms within several hours to a day can be expected.
What can I do to protect myself and my family from the harmful health affects of air pollution?
Of course the most effective approach is to reduce or eliminate air pollution in the first place, so it is important to raise concerns and advocate for change to governments and with the health care community. We know that when air pollution is reduced that there are measurable improvements in the health of populations and there are many good example from around the world. In the mean time, maintaining a good level of overall health is probably the single most important thing that people can do to reduce the impacts of air pollution. We also see that for those who can afford them (costs are ~$100-200 U.S.) room air cleaners – those with a HEPA filter – are very effective. Operating one in the bedroom at night and in the main room of a home can be helpful. There is also some evidence that diets high in antioxidants and omega-3-fatty acids (i.e. from fish) can provide some protection (but we generally do not advise that people take supplements). Finally, for people with heart or lung disease it is important to consult with a physician and maintain the use of prescribed medications as these have also been found to blunt the effects of air pollution.
Can I exercise outside in hazardous air? Does it really make a difference?
We know that exercising is very good for health and that in general the benefits of exercise outweigh the harmful effects of exposure to air pollution while exercising. However, it is best to avoid exercising outdoors during periods of especially poor air quality or in locations where air quality is poor and to try and select locations and periods with better air quality.
As we head out of the particulate-matter season (winter) and into the heavy ground-level ozone period of Spring and Summer, how bad is ozone for our health? And what can we do?
Unlike particulate matter which seems to lead to effects on many organ systems the effects of ozone appear to be mainly limited to the lungs. Still, it is a very powerful pollutant that can especially affect asthmatics or people with chronic lung disease. The good news is that ozone has a distinct daily pattern and the highest levels peak in the mid to late afternoon, with levels generally dropping substantially in the evening and night so one can try to remain indoors during the mid to late afternoon period. Also, ozone levels indoors are usually very low so remaining indoors offers protection – again somewhat different than particulate matter where indoor levels are approximately 70% of outdoor levels (air conditioning may lead to somewhat lower levels.
What else should we know about health and air pollution?
The more we study the effects of air pollution the more we find that it affects many types of diseases – this is because the initial impact of air pollution on the lungs leads the body to respond. This response is inflammation and when inflammation continues (because the air pollution is still present or because the body’s response cannot neutralize the air pollution) the bloodstream becomes filled with inflammatory cells and molecules – these can then act of many different parts of the body – including the heart and the brain. We now see evidence that air pollution may even affect mental health and cognition.
On a more positive note, for most people the effects of air pollution are relatively small…what makes it important from a public health perspective is that we are all exposes so in aggregate this becomes important for the health of the population as a whole. Most importantly, unlike many other health concerns we don’t need to search for a cure or solution – we already know how to manage and reduce air pollution and we know that doing so is a very cost effective way to improve health.