A recent surge of evidence links micro particulate air pollution with an increased risk for cardiovascular events. This is alarming as both short- and long-term exposure is associated with an abnormally high incidence of heart attacks, strokes, cancers, respiratory diseases, auto immune diseases and dementia.
7 Tips to Help Patients Reduce Health Risks
During haze or bad pollution:
- Stay indoors when the PSI is >300
- Avoid strenuous activities or outdoor physical exertion
- Wear a mask (preferably the N95 mask)
- Avoid smoking areas, car parks or areas with high vehicular traffic
- Use portable/central air cleaning systems to reduce concentrations of indoor air pollutants
- Consult a GP immediately if breathlessness, chest pains or fever develops
- Ensure adequate hydration and rest
Of interest is the pathogenicity of micro particulate matter. These microscopic pollutants, also known as ‘fine soot’ are formed as a result of incomplete combustion of fossilised fuels — diesel, in particular. They are categorised according to diameter, with fine particles fixed at 2.5 μm (PM2.5). Their deadly effects depend on particulate size, with most PM10 particles seen to deposit in the upper airways. PM2.5 and PM0.1 particles can penetrate the lung alveoli into the systemic circulation. Smaller fine and ultrafine (<100 nm) PM, are associated with more serious adverse effects.
The World Health Organisation reported that air pollution was directly responsible for 3.7 million deaths. The data comes from western metropolitan areas with strict antipollution measures, e.g. Euro 6 emissions standards. Most Asian cities, which lag far behind Western standards of pollution control, see a much higher estimate of mortality figures.
Interestingly, acute exposure to PM2.5 results in a higher rate of death due to cardiovascular, than respiratory disease. The risk increases with every 10 μg/m3 increase of PM2.5, with no lower limit to its safety level. Acute exposure can push up the risk of heart attacks by five per cent within a day, with an alarming 69% increase in cardiovascular deaths after acute exposure in the short term. Worldwide, health organisations have recognised the association between PM2.5 and cardiovascular disease. Of note, developing nations have PM2.5 levels that are at least 10 times higher than seen in cities within the United States.
Singapore is no exception, with one of the highest automobile densities in the world, registering approximately 1 million passenger vehicles, and an estimated 200,000 goods & commercial vehicles (which use diesel engines of outdated Euro 4 and below standards) in a compact land area of approximately 600 square kilometres. Of interest to the topic, are four of the world’s biggest cities i.e. Paris, Madrid, Athens and Mexico City, which have taken action to ban diesel vehicles from their city centres in a few years’ time. Other major cities are expected to follow suit.
These actions reinforce the impact of PM2.5 pollution on public health, and is one of the most urgent health problems that need to be addressed worldwide.
By Dr Yong Quek Wei, Senior Consultant, Department of Cardiology, Tan Tock Seng Hospital