Unfortunately, a very difficult question to answer and sometimes it may be impossible to know for certain what the impact to a particular sample is.
Temperatures above 10 degrees may mean that target parameters are lost due to volatilization or microbial activity, therefore potentially a biased low result.
However, some parameters are recalcitrant or are otherwise not impacted by microbial activity or changes in temperatures above 10C (like metals and a variety of inorganics).
This situation is best resolved within the context of the specific project and submission, and the following should be considered when assessing the impact.
- Were the samples submitted on the same day as they were collected? (in which case, temperatures above 10C are typically not a concern).
- Are the reported results for the sample(s) exceeding the standard? (in which case temperatures above 10C would not have had a meaningful impact to the results).
- What analyses are being requested on the sample(s)? (organic parameters may be more prone to impact than inorganics).
Since any effect of temperature on data is impossible to quantify (because the starting point is unknown, to measure the significance of any change), the data should be validated within the context of the project.