The similar issue with spirometry was that 70% (0.7) upwards was the acceptable value for which an employee tested could be told the result are within range after taking into account other characteristics. But now i was told that 80% (0.8) upwards was the acceptable value and i have to ask here others opinion on this.

As there  is a requirement for a physician to have an overview of the HS programme, I would ask you OH physician what they would like to have referred to them/ or for you to tell individuals.

Are you looking for early onset Occupational Asthma , or as a baseline for employment e,g police?Or COPD?

I don't think it is as simple as a value of FEV1%. This is the ratio of the FEV1 /FVC

Those with asthma  breathe out a similar volume but take longer to do so.. so the FEV1 is lower. If you get a person with big lungs and a big ribcage they might have an  an FVC of 120% an a  normal FEV1.

 The ratio will be low, but the person does not have respiratory obstruction. For asthma , i suggest there also needs to be a low FEV1. but discuss this with your physician.You also get some idea from the shape of the graph if there is obstruction...

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3019348/

The GOLD guidelines aim towards uniformity and simplicity in the area of COPD diagnosis and management. To achieve this end, and for greater use at primary and secondary levels of health care, developers of these guidelines have kept the diagnostic criteria for identifying airflow limitation very simple. In fact, they have gone back in history and have again proposed use of a fixed cut-off of 70% for FEV1/FVC for this purpose. Practically speaking, a person's FEV1/FVC ratio is an individual figure that depends, among other factors, on his/her race, ethnicity, body built and age. Because of this, it is almost impossible to accurately predict an individual's normal FEV1/FVC ratio. It is generally accepted that FEV 1/FVC ratio decreases with increasing height and advancing age. Logically, therefore, it is not possible to choose any single value that can reliably discriminate healthy from diseased individuals. For epidemiological and clinical purposes, we generally rely on figures derived from apparently healthy population. Statistically derived values that take into account a person's age, gender and built, and provide a lower estimate of range of normalcy, are clearly a better option., Thus the real point of concern is whether this simplicity of the GOLD philosophy is achieved at the cost of clinical and scientific validity?

http://journals.lww.com/joem/Fulltext/2011/05000/Spirometry_in_the_Occupational_Health_Setting_2011.16.aspx

 As pulmonary function declines with age, the fifth percentile LLN also declines, labeling only 5% of normal individuals in each age group as “abnormal.” In contrast, as age increases, increasing proportions of nonexposed healthy individuals fall below 80% of predicted or a measured FEV1/FVC ratio of 0.70, creating an increasing pool of false positives in an aging workforce.19,29,30 These fixed definitions of abnormality also yield some false negatives in young workers. As recommended by the ATS since 1991,5,19 using the fifth percentile LLN to define abnormality for the major spirometry measurements avoids these problems. As described later, the LLN is used to identify both obstructive and restrictive impairment patterns.