Diesel Air Pollution Linked To Heart Attack And Stroke In Healthy Men

Featured Article
Main Category: Cardiovascular / Cardiology
Also Included In: Water - Air Quality / Agriculture;  Blood / Hematology;  Men's health
Article Date: 09 Nov 2007 - 10:00 PST

email to a friend   printer friendly   opinions  

UK and Swedish researchers found that diesel fumes from road vehicles increased blood clots and platelets in healthy volunteers. These are symptoms closely linked to increased risk of heart attack and stroke.

The researchers reported the results of a small study to a meeting of the American Heart Association's Scientific Sessions 2007 held in Orlando, Florida, earlier this week.

Previous observational and epidemiological studies have also shown a close link between exposure to traffic pollution and heart attack, said study lead author Dr Andrew Lucking, who is a cardiology fellow at the University of Edinburgh in Scotland, UK.

"This study shows that when a person is exposed to relatively high levels of diesel exhaust for a short time, the blood is more likely to clot. This could lead to a blocked vessel resulting in heart attack or stroke," said Lucking.

Lucking and colleague carried out a double blind, randomized cross-over study on 20 healthy male participatns aged from 21 to 44. Using a specially designed exposure chamber, the men were separately exposed to filtered air (this was the control) and then to 300 mg per cubic metre (mcg/m3) of diesel exhaust fumes, which is roughly the concentration you breathe in while standing by a busy street.

The researchers measured clot formation, blood coagulation, platelet activity and markers of inflammation by attaching each participant to a perfusion chamber and allowing a small amount of blood to pass through it. This was done 2 hours after exposure and then again 6 hours after exposure.

Clot formation was assessed by passing the blood through a special shear chamber that simulates the types of pressure the blood would be under in blood vessels. The researchers tested the blood at high shear and low shear.

Platelet activation was assessed by measuring the number of platelets associated with white blood cells. When platelets are activated they stick to white blood cells like neutrophils and monocytes and form clumps, thereby playing a key role in the formation of blood clots.

The results showed that:

• Breathing diesel fumes increased clot formation in the low shear chamber by 24.2 per cent compared to breathing filtered air.


• In the high shear chamber the increase in clot formation from diesel fumes was 19.1 per cent.


• These effects were observed at both 2 and 6 hours after exposure to diesel fumes.


• Breathing diesel fumes increased platelet-neutrophil aggregates from 6.5 to 9.2 per cent 2 hours after exposure.


• It also increased platelet-monocyte aggregates from 21 per cent to 25 per cent 2 hours after exposure.


• But at 6 hours after exposure the platelet activation increases due to diesel fumes were not statistically significant.

Lucking said: "High levels of traffic pollution are known to increase the risk of heart attack in the immediate hours or days after exposure."

He said this study showed a "potential mechanism that could link exposure to traffic-derived air pollution with acute heart attack."

Although these results apply to diesel engine fumes, it's not clear whether gasoline powered engines would have the same effect, said the researchers. Diesel fumes contain a much higher concentration of very fine particles, they said.

Diesel engines are on the rise because they offer superior fuel economy, but, as Lucking explained:

"While diesel engines burn more efficiently, they also put more fine particulate matter into the air."

The researchers said while exercise was good for people with cardiovascular disease, they would not recommend they exercise near traffic congestion.

The UK and Swedish team will be working together on the next step, which is to test the effectiveness of the particle traps fitted to diesel engines to reduce exhaust particles.

"Exposure to air pollution clearly is detrimental and we must look at ways to reduce pollution in the environment," said Lucking.

An earlier study published in the 13th September issue of the NEJM , also by UK and Swedish researchers, showed that men with coronary heart disease who inhaled diesel fumes experienced a three fold increase in stress on the heart.

Click here for the American Heart Association.

Click here for our report of the September NEJM article on the effect of diesel fumes on men with coronary heart disease.

Written by: Catharine Paddock
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

• Additional
• References
• Citations