The problem lies also with infrastructural difficulties. If formaldehyde is used it will mean that bigger air evacuation systems must be implemented and a much longer air evacuation time needs to take place before people can enter the fumigation rooms. In practice this turns out to be an almost impossible nut to crack. Two hours after air evacuation and fumigation of only 5g/m³ of paraformaldehyde, the MEL of 0.3 ppm still is exceeded by 14 times. Therefore using less formaldehyde doesn’t really makes it any easier to stay working within the allowed exposure limits, it also of course raises questions on its bactericidal efficacy.