You could buy an explosive gas detector: https://www.amazon.com/s?k=explosive+gas+detector https://www.amazon.com/s?k=explosive+gas+detector I am not sure how

You could buy an explosive gas detector: https://www.amazon.com/s?k=explosive+gas+detector https://www.amazon.com/s?k=explosive+gas+detector I am not sure how sensitive each model is.