Arthritis is made worse in damp and cold environments. A dehumidifier produces a much healthier environment for suffers of Arthritis.
Our bodies can be affected by the weather. Joints in our bodies contain sensory nerves called baroreceptors, they respond to changes in the weather. High humidity causes low air pressure and your body responds to changes in the air pressure. For example, when your surroundings are damp, the barometric pressure drops, causing our tendons, ligaments, and muscles to expand. The baroreceptors in our body respond, helping the central nervous system to regulate the resistance of blood vessels and the heart's contractions. For those who already have muscle or joint pain (especially arthritis), muscle, tendon and ligaments expansion can irritate the already-sensitive areas.
So by balancing out your humidity levels this helps keep air pressure stable therefore relieving some pain from those who have arthritis or muscle and joint pain.