Rather than logos, have participants use a famous tag line or marketing slogan. Break the group into small teams of four to six members. Have the team choose a logo that best represents them. Alternatively, choose a logo that best represents the project or the whole work group they belong to.
Your body makes vitamin D when your skin is exposed to the ultraviolet B (UVB) rays in sunlight. About 5 to 30 minutes of exposure to the skin on your face, arms, back or legs (without sunscreen) two times every week is enough. But, too much exposure to sunlight is a risk for skin cancer, so you should use sunscreen after a few minutes in the sun, even on hazy or cloudy days.
A typical human needs about 50 liters of oxygen per hour. That translates to 10,000 houseplant leaves, or maybe 500 to 1000 houseplants to support one human. Maybe 100 houseplants would make a noticeable difference. All of these figures are in the right order of magnitude, but not exact.