How do you test your carbon monoxide alarms are detecting CO?

[Bettyhatesavocados]

The guide says to test the sensor when first setting up to ensure the carbon monoxide alarm is indeed detecting carbon monoxide. It suggest incense sticks or CO spray to test. The only CO spray online seems to have very mixed reviews.
Thanks!

I’ve never heard of testing by subjecting the meter to actual carbon monoxide, not by the householder anyway. I just test to make sure it’s still in working condition by pushing the on button and see if it makes the screeching sound. Apart from that, I buy Which? Best Buy detectors and trust they work. I’m a landlord and fit them in my rentals.

I just press the test button same as I do for the smoke alarms. I don't test the smoke alarm with actual smoke.

I buy a branded product, sharpie the date I bought it on and only keep it for the length of time suggested by the product. I have had mild carbon monoxide poisoning (dodgy student flat) and don't feel like I need to more than the above.

I test them by pressing the button same as the smoke/ heat alarms.

Pressing the button on the alarm is a good start, but that is only testing that it has power and can alert you if the sensor picks anything up. It sounds as if you want to check the actual sensor is working and the other respondees are correct in only buying from reputable companies and suppliers, ensuring they comply with EN50291 standard and are within their expiry date. The short answer is there is no real way to check without exposing yourself to CO, which is what the sprays sold online do. If you are asking because you suspect you are being exposed to CO then please look at www.co-gassafety.co.uk and contact them for advice. Make sure your property is well ventilated until you know you are safe.