Sandy McFadden

This is a very simple plugin which requires almost no configuration.
All you need to do is go to the Appearence then Widgets area in the Admin Dashboard. 
Once you are there drag the BMI Calculator widget onto the widget area you would like it added to.
The only two settings are the title and the color. The color is the hex color you would like the results background to be.
A lot of the code was adapted from 
<a href="http://codereview.stackexchange.com/questions/21581/calculating-body-mass-index-bmi" title="Inspiration Code" rel="nofollow ugc">Stack Exchange Thread</a>

Healthy BMI Calculator

Adds a shortcode and widget that will display a simple BMI Calculator on your site. Works with both metric and US style measurements.

patrol220

Air Quality Plugin shows air quality data from closest detector of localization which you will give in settings of plugin. In plugin settings localization must be provided to determine which detector will be chosen. You can set Google Maps API key in settings to make that thing easier. After giving Google Maps Api key you will get new input field where you can specify your localization. It can be name of the city, but in your city there can be multiple air quality detectors so for more accurate results you should put name of the street. 
Plugin is using waqi.info JSON API to get data about air quality.
In settings administrator have option to let every user to set localization from Settings -> AQP Settings what they want.
Plugin additionaly displays some info about weather from detector if there is any given. You can disable it from administrator options.

Air Quality Plugin

This plugin was made mainly to display air quality from closest air pollution detector

Healthy BMI Calculator vs Air Quality Plugin