进行了一些更改，首先是为了确保XML文件有效，其次是为了从正确的位置提取正确的数据

// Loop through each CSV file
foreach ($csvFiles as $csvFile) {
    $csvFilePath = __DIR__ . '/' . $csvFile;
    
    // Open the CSV file
    if (($handle = fopen($csvFilePath, 'r')) !== false) {
        // Create an XMLWriter instance

        /* You cant write the Station element until you have read the csv file
            as it needs data for its properties from there
            So moved inside the while loop
        */

        $xmlWriter = new XMLWriter();
        $xmlWriter->openURI(csvFileToXmlFile($csvFile));
        $xmlWriter->startDocument('1.0', 'UTF-8');

        $flagFirstLineWritten = false;      // control writing on Station element only once
        
        while (($data = fgetcsv($handle,10000,';')) !== false) {
            // Skip empty lines
            if (count($data) === 0) {
                continue;
            }
            /*
                output the Station element with its properties only once
            */
            if ( ! $flagFirstLineWritten ) {
                $xmlWriter->startElement('Station');
                $xmlWriter->writeAttribute('id',        $data[4]);
                $xmlWriter->writeAttribute('name',      $data[17]);
                $xmlWriter->writeAttribute('geocode',   $data[18]);
                $xmlWriter->endAttribute();
                $flagFirstLineWritten = true;
            }
            
            // Ensure the array has the necessary indexes
            if (count($data) >= 4) {
                // Extract the necessary data
                /*
                    convert the DATE to a timestamp
                */
                $ts = (new DateTime())->createFromFormat( DateTimeInterface::ISO8601, $data[0]);
                                
                // Check if the attribute has a value
                if (trim($data[3]) !== '') {
                    // Start XML record element
                    $xmlWriter->startElement('rec');
                    $xmlWriter->writeAttribute('ts',    (string)$ts->getTimestamp());
                    $xmlWriter->writeAttribute('nox',   $data[1]);
                    $xmlWriter->writeAttribute('no',    $data[2]);
                    $xmlWriter->writeAttribute('no2',   $data[3]);
                    // End XML record element
                    $xmlWriter->endElement(); // end rec
                }
            }
        }

        $xmlWriter->endElement();   // station element
        $xmlWriter->endDocument();
        $xmlWriter->flush();
        fclose($handle);

        // Output success message
        $xmlFile = csvFileToXmlFile($csvFile);
        echo "XML file generated successfully: $xmlFile\n";
    }
}

// Function to convert CSV file name to XML file name
function csvFileToXmlFile($csvFile) {
    $fileParts = pathinfo($csvFile);
    $xmlFile = $fileParts['filename'] . '.xml';
    return $xmlFile;
}

结果，示例

<?xml version="1.0" encoding="UTF-8"?>
<Station id="203" name="Brislington Depot" geocode="51.441747180510106, -2.5599558321904605">
    <rec ts="1546326000" nox="18.5" no="12.5" no2="3.75"/>
    <rec ts="1546412400" nox="163.75" no="55.0" no2="71.0"/>
    
    . . .

    . . .
</Station>