How to choose an ergonomic chair.

To help you to choose an ergonomic chair you can complete the Ergonomic Seating Evaluation Form,. You should also check whether the chair will meet at least the following criteria:

* Does the seat pan feel comfortable and fit your shape?
When you sit in the chair the seat pan should be at least one inch wider than your hips and thighs on either side. The seat pan should not be too long for your legs otherwise it will either catch you behind the knees or it will prevent you from leaning fully back against the lumbar support. Most ergonomic chairs have a seat pan with a waterfall front that prevents the seat from catching you behind the knees. The seat pan should also be contoured to allow even weight distribution and it should be comfortable to sit on.
* Is the seat chair height adjustable?
For preference the chair should be pneumatically adjustable so that you can adjust seat pan height while you are sitting on the chair. Some chairs have a mechanical height adjustment (spinning) mechanism that is also acceptable.
* Is the range of height adjustment of the chair sufficient to meet the needs of all users?
You should be able to adjust the height of the seat pan so that the front of your knees is level or slightly below level and your feet are firmly on the ground. In most cases there should be no need for you to use a footrest. The mechanism to adjust seat height should be easy to reach and operate when you are seated.
* Does the chair have a comfortable lumbar (lower back) back rest?
Many chairs have cushioned lumbar supports that can be adjusted up and down and forwards and backwards to best fit your shape. If the chair will be used by multiple users then this level of adjustment may be required. If the chair has a fixed height lumbar support and it feels comfortable when you sit back against this, and you will be the primary user of the chair then a fixed lumbar support may be acceptable.
* Is the chair back rest large enough to provide good back support?
Many chairs have back supports that are large enough to provide mid-back and upper-back support, in addition to good lumbar support.
* When you sit back against the lumbar support is there ample space for hip room?
Insufficient hip room can make you sit too far forwards on the seat pan so that you will not have enough thigh support.
* Does the seat pan still feel comfortable after you've been sitting in it for 60 - 120 minutes?
If the seat pan is made from low-density foam then continuous use can cause it to become permanently deformed and then it will not provide adequate cushioned support. Insufficient cushioning and inappropriate contouring can cause discomfort, imbalance and hip and back fatigue.
* Does the chair backrest recline and support your back in different positions?
Movement of the back while you are sitting helps to maintain a healthy spine. Look for chairs that allow you to easily recline, that provide you with good back support in different recline postures, and that have a back that tracks where your back is. Locking the chair backrest in one position generally isn't recommended or beneficial to users.
* Does the chair have a 5 pedestal base?
If chair mobility is important to help you to do your work then the chair should have at least a 5 pedestal base with casters that glide freely over the floor surface. You may also want to choose a chair that swivels easily.
* Do you need armrests on your chair?
If so, are the armrests broad, contoured, cushioned and comfortable? While sitting can you easily adjust the height of the armrests and can you move the armrests closer together or further apart? Can you easily move the arms out of the way if you need to do this?

Other considerations:

* Do you need a footrest?
In the vast majority of situations you should not need a foot support to be able to sit comfortably on your chair? However, if you do need a foot support then choose a free-standing floor-mounted support that allow you to rest your feet out in front of you in a comfortable manner.
* What chair covering is best?
Chairs can be covered in a variety of upholstery materials, each of which has benefits and concerns. Vinyl and vinyl-like coverings are easy to clean and spill resistant, but they don't breath and if the chair begins to heat up under the thighs uncomfortable amounts of moisture can accumulate. Cloth upholstery is the most common covering, but this is less resistant to spills and more difficult to clean. A cloth covered seat pan can also become warm and moisture laden, and cloth covered foam seat pans can be a significant source of dust mite allergen. When selecting your chair covering think about cleaning and maintenance issues and plan appropriately.
* Do you need an adjustable tilt seat pan ?
In most situations this is not an essential feature. In some situations it can be helpful to change the tilt of the seat pan to help to maintain a balanced seated posture.

source: www.ergonomic-resources.com