table of contents seasonality our business experiences seasonality that varies by product line .
because more construction and do-it-yourself projects occur during the second and third calendar quarters of each year in the northern hemisphere , our security product sales , typically , are higher in those quarters than in the first and fourth calendar quarters .
however , our interflex business typically experiences higher sales in the fourth calendar quarter due to project timing .
revenue by quarter for the years ended december 31 , 2015 , 2014 and 2013 are as follows: .

first quarter
second quarter
third quarter
fourth quarter
2015
22% ( 22 % )
25% ( 25 % )
26% ( 26 % )
27% ( 27 % )
2014
22% ( 22 % )
25% ( 25 % )
26% ( 26 % )
27% ( 27 % )
2013
23% ( 23 % )
26% ( 26 % )
26% ( 26 % )
25% ( 25 % )

2015 fourth quarter revenue includes the full-quarter impact of the acquisitions of simonsvoss , axa and milre .
employees as of december 31 , 2015 , we had more than 9400 employees , approximately 26% ( 26 % ) of whom have the terms of their employment covered under collective bargaining agreements .
this includes non-management european employees who are represented by national and local works councils .
environmental regulation we have a dedicated environmental program that is designed to reduce the utilization and generation of hazardous materials during the manufacturing process as well as to remediate identified environmental concerns .
as to the latter , we are currently engaged in site investigations and remediation activities to address environmental cleanup from past operations at current and former manufacturing facilities .
we are sometimes a party to environmental lawsuits and claims and have received notices of potential violations of environmental laws and regulations from the u.s .
environmental protection agency ( the "epa" ) and similar state authorities .
we have also been identified as a potentially responsible party ( "prp" ) for cleanup costs associated with off-site waste disposal at federal superfund and state remediation sites .
for all such sites , there are other prps and , in most instances , our involvement is minimal .
in estimating our liability , we have assumed that we will not bear the entire cost of remediation of any site to the exclusion of other prps who may be jointly and severally liable .
the ability of other prps to participate has been taken into account , based on our understanding of the parties 2019 financial condition and probable contributions on a per site basis .
additional lawsuits and claims involving environmental matters are likely to arise from time to time in the future .
we incurred $ 4.4 million , $ 2.9 million , and $ 2.1 million of expenses during the years ended december 31 , 2015 , 2014 , and 2013 , respectively , for environmental remediation at sites presently or formerly owned or leased by us .
as of december 31 , 2015 and 2014 , we have recorded reserves for environmental matters of $ 15.2 million and $ 8.8 million .
of these amounts $ 2.8 million and $ 2.4 million , respectively , relate to remediation of sites previously disposed by us .
given the evolving nature of environmental laws , regulations and technology , the ultimate cost of future compliance is uncertain .
available information we are required to file annual , quarterly , and current reports , proxy statements , and other documents with the u.s .
securities and exchange commission ( "sec" ) .
the public may read and copy any materials filed with the sec at the sec 2019s public reference room at 100 f street , n.e. , washington , d.c .
20549 .
the public may obtain information on the operation of the public reference room by calling the sec at 1-800-sec-0330 .
also , the sec maintains an internet website that contains reports , proxy and information statements , and other information regarding issuers that file electronically with the sec .
the public can obtain any documents that are filed by us at http://www.sec.gov .
in addition , this annual report on form 10-k , as well as future quarterly reports on form 10-q , current reports on form 8-k and any amendments to all of the foregoing reports , are made available free of charge on our internet website ( http://www.allegion.com ) as soon as reasonably practicable after such reports are electronically filed with or furnished to the sec .
the contents of our website are not incorporated by reference in this report. .

Question: considering the year 2014 , what are the variation between the expenses for environmental remediation at sites and the reserves environmental matters , in millions?
Answer: 5.9
Explanation: it is the difference between the expenses' value and the value of the reserve in that year .
Calculation: subtract(8.8, 2.9)