For persons in charge of church maintenance:

• Build new buildings with less toxic materials.
• Use electric utilities or radiant heat.
• Eliminate the use of air "freshener" sprays, incense, and fragrance-emitting devices.  At least one restroom (perhaps the family accessible restroom) should have no air fresheners of any kind. 
• Advise the congregation in advance and persons known to have MCS in particular about planned maintenance projects.  Then, carry out those projects so as to avoid or eliminate quickly the smells of paint, finishes, new carpets, and other chemicals. 
• Use least toxic, natural, and unscented cleaning and sanitizing products in restrooms, etc.  Do cleaning early in the week so rooms have time to air out. 
• Ventilate buildings with clean fresh air and/or use portable room air filters.
• Avoid pesticides.  Use least toxic integrated pest management.  If you need to use pesticides, once again advise the congregation in advance and persons known to have MCS in particular.
• Declare a scent free zone in a room with a window into the sanctuary and a door directly to the outside (but not right into the parking lot).  No one who sits in that section would wear fragrances or use scented detergents in hair or clothes.  Advertise to the community that this is available!  
• If a separate room isn't possible, try making a corner of the sanctuary scent free.
• Provide alternative seating for those sensitive to pew cushions and metal chairs.