Getting rid of strong odours

I have been driving a Renault Kwid 800cc since December 2016 and I recently put custom-made fabric covers on the seats. But now there is a strong plastic odour that refuses to go away, even though I have also been using an Aquaguard air purifier. I believe this odour is a health hazard. How do I get rid of it?
Antony D’souza, via email

AAA Indeed, any prolonged unnatural smell can be hazardous. So, firstly, it is important to understand where the odour is originating from. Have you retained any plastic covers in the car, like on the seats and sun visors? These covers are made of poor-quality recycled plastic that heats up quickly and releases a foul odour which is toxic.

The first thing to do is to get rid of all plastics immediately.

Next, do a complete check of the cabin – look in the pockets, under the seats, floor mats and even in the glove compartment for any litter. Baby bottles in the back seat, mouldy fruit in forgotten bags or unidentified blobs that may have been dragged in from someone’s shoe could also be the cause. Hence, thoroughly remove any junk from the cabin and open the doors for a while to let any lingering odour dissipate.Use a mild shampoo to clean specific areas and use a wet vacuum cleaner (or a hair dryer) to remove all moisture.