Updated 15 August 2017

SA's old diesel vehicles continue to fuel allergies

Over the last decade, manufacturers of diesel engines have made giant steps forward in reducing emissions, but diesel fumes remain a major cause of allergies and other respiratory conditions.


According to one of SA’s leading pharmaceutical companies, specialising in treating allergies, nasal allergies already affects close to 20 million people in the country – a figure which is set to increase  as a result of airborne pollutants amongst others. 

Increasing the allergic immune response

Wilmi Hudsonberg, spokesperson for Pharma Dynamics says while the introduction of new diesel engines, which now come equipped with advanced filters and catalysts, are encouraging, SA’s car parc is relatively old.

“The average age of a light passenger vehicle in SA is around 11 years, while most taxis and buses that typically use diesel are 14 or older. The maturity of our car parc has a direct implication on the quality of our air and subsequently our health.

“Diesel pollutants can either exacerbate the symptoms of those already prone to allergies or trigger latent allergic reactions in those who were previously not allergic, causing the body to create more antibodies and thereby increasing the allergic immune response.

Read: Top 10 allergy triggers

“Diesel exhaust contains about 100 times more carbon particles than petrol and remain airborne for a long time. To make matters worse, when pollen particles bind to diesel particles, they go a lot deeper into the airways since diesel particles are much heavier and, in turn, a chemical reaction takes place when the two combine, which make it more allergenic,” she says.

Large number of older diesel vehicles

In South Africa, diesel car sales are rising and show no signs of slowing down. Since 2008 overall sales of diesel-powered vehicles have almost doubled with diesel cars making up about 22% of our country’s car parc, of which about 46% (1 042 510) are older, non-emission controlled diesels.

Hudsonberg says the large number of older diesel vehicles on our roads and their continued use poses a serious health risk.

Read: 5 things to know before taking an antihistamine

She cites figures from the most recent "State of SA’s Air" report released by the Department of Environmental Affairs, which highlights that the three biggest types of air pollution are sulphur dioxide, particulate matter 10 and particulate matter 2.5 – the latter emanating mainly from diesel tailpipe emissions.

“To control exhaust emissions in an environment such as South Africa, vehicle roadworthiness tests should be compulsory within four years of the first registration and every two years thereafter. In a recent test carried out by the National Vehicle Testing Association on more than 1 000 cars in SA, about 80% weren’t in a roadworthy condition, which is alarming.

Read: Semen and other bizarre allergies

“In addition, drivers of old diesels, especially those owning and managing fleets should consider fitting their vehicles with Diesel

Particulate Filters (DPF), which traps soot and harmful particulates in the exhaust, thereby significantly reducing tailpipe emissions,” she advises.

Rather close the windows

Hudsonberg adds that commuting can also add to allergy sufferers’ misery. “When traveling to work – whether in a bus, taxi or car, rather close the windows and turn the air conditioner on. The aircon should filter out all the diesel particles to lessen your exposure and alleviate symptoms.”

For more information about allergies and treatment options available to sufferers, visit 

Read more:

What are allergies?

Causes of allergies

Preventing allergic reactions

Pharma Dynamics is one of the leading generic pharmaceutical companies in South Africa


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Dr Morris is the Principal Allergist at the Cape Town and Johannesburg Allergy Clinics with postgraduate diplomas in Allergology, Dermatology, Paediatrics and Family Medicine dealing with both adult and childhood allergies.

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