You also have procedure/methodology... 90db at what distance? open or closed hood? If I put a install a genset, the housing has a db rating for 23ft, and my calculations at the property line may seem straight forward, but... summer to winter air density, surrounding vegetation and structure reflection etc, affects things. prolonged exposure at 85db can cause hearing damage. If you have a production facility, you have to enforce hearing safety. All of which makes me think Ineos is just making this shit up and pulling a number out of their ass they know you wont top. 90db WHERE??