Stock and flow model is a practical method to predict and calculate chemical or substance concentration in a building with a simple model. However, more sophisticate approach has to be done to measure chemical concentration in human tissue, how it move and concentrated in the living thing organs, the body. Therefore physiologically based pharmacokinetic may be applied for this case. Read the rest of this entry »

We have practiced about reducing radon at controlable level with exchanging air within the building. The exercise about stock flow model in previous post can be applied to calculate the concentration on radon in our own house, of course if you have radon dosemeter. This post will drill you to understand more about stock model flow. Read the rest of this entry »

We have learned simple example to measure radon concentration in indoor building with several information known such as average annual indoor radon concentration and air change per hour. I suggest to review again the stock flow model and example part 1. Now we will practice to measure and calculate the flow rate of radon into a house that has average annual radon concentration of 20 pCi/L. How much additional airflow would be necessary to reduce the concentration in the house to become 2 pCi/L? Read the rest of this entry »

Now you have learned about a very simple example of stock model example which in the prevous post, it gave TCA example. The more advance example now is talking about radon. More information about radon can be read at Radon: risk around us. Read the rest of this entry »

Many models in our daily life can be categorized as a stock flow model. And unfortunately, they contribute hazardous effect to our health. And to some extend, we do not even consider it that those things are dangerous to our health. Read the rest of this entry »

Statistics is fundamental for risk analysis especially to quantify the risk, thus it is important subject to be taked by any of risk analysts. The process of constructing and solving problems for risk assessment can be viewed as two broad types of activity, building a useful mental picture, or model, of the system and getting reasonable and objective values into the model. Read the rest of this entry »

When the relationship on a problem between exposed population and cancer risk had a linear curve, sometimes the shape of the curve implies something abut either the data used to find it or a belief in the underlying mechanism causing it. It may the case that the realtionship between radon exposure and lung cancer risk is linear, but then again it may not. Other some possible mechanisms that might cause certain curve shapes, as well as some techniques for simply fitting a curve to data, regardless of possible mecahnisms. Either modeling or simple curve fitting can be used to extrapolate to exposures beuond the data range. Read the rest of this entry »

Physiologically based pharmacokinetic (PBPK) models are stock and flow models used to think about how chemicals move and concentrate within the body. While many dose-response experiments look only at the dose applied to the animal (food, air or skin), understanding what goes on inside the body can provide much better information on why a given response occurs. Read the rest of this entry »

This post will briefly describe about radon and why it is worthy for attention. Radon is present around us, with or without we realize it. Though, radon poses risk to our health, thus it is necessary to reduce its concentration to a certain level believed to be safe for our health. Read the rest of this entry »